Sunday, 30 June 2019

Mercane on local country roads (longer ride)

I thought I'd take the Mercane out today and just do a trip down to the gorge road and back. Mixture of light hills with a few shorter steep ones.

I left at about 1:22pm, stopped a few times for a few minutes to play with some settings and make a quick video and got back at about 1:50pm, so about 28min all in all.

Here is the route:


with a short run up the hill to visit a mate.

Battery start V = 52.3 at the end of the trip the battery was still showing 47.9V (which is just below 3.7V per cell). Not a bad showing and I guess that while I could push another 5 or so km out of them without going below "undesirable" levels of discharge (and perhaps impacting life). So basically a 2.3V drop over the trip.

I started on Eco, but quickly decided to just run it on Full and used cruise control for the trip. Eco was giving me 19kmh on the flats while Full was giving me 24 (I did not used "uleashed")

Because I don't have any way to edit video on this laptop, you'll have to accept just one installment.


A quick look at Google shows that there is quite some climbs in that

And while you aren't drawing much power on the downhills the uphills suck it out harder than the downhills "rest the battery" (and even if it had recovery braking, I would not have benefited because I wasn't slowing down by brakes much).

I had a lovely time.

Saturday, 29 June 2019

lighting my way

The scooter (well and my bicycles in the past too) needed a headlight, I liked the look of this one on eBay and the price was good too


As soon as I took it out of the package I was clear that it just wouldn't sit on the bars. Sure enough, I was right, first ride and its just drooping down with every bump, it was utterly annoying. I was having to re-orient it every bump.

Then after I got home and was just chilling, it occurred to me: "Say, I wonder if I hung it upside down would that equate to the same angle I wanted it to be on".

Bugger me but it did!


Its perfect in this orientation and (bonus) I don't need to even have that rubber strap very tight at all, so its not likely to snap and render it useless quick smart. Its so perfect it makes me wonder if the designer intended this but the marketing were too dumb to understand?

So if you buy one of these lights (and it seems pretty good actually) then make sure its under the bar because its "well hung".

(sorry)

PS: as the question was asked if it actually stacked up to its claimed lumens I thought I'd measure it.


So, there you go

being visible at night

While I love the look of the Mercane, its not exactly good for being seen by drivers when being used at night. As well that headlight is more of a running light. allowing others to see it from the front more than lighting the way for me to see.

So I decided some reflective tape on the "stem" was in order


just looks red, but when you shine a light at it (like my camera flash) it really stands out ..


impressive ... outside in the dark you can't see the scooter, but that red reflects your light like a beacon (say if someone is driving a car and you're in their headlights).


Fantastic. (even matches the Ducati logos ;-)

Like CASE said: "Safety First Cooper"


Mercane: wet weather protection

I happen to think that  the rear wheel on the Mercane Wide Wheel looks pretty cool, but equally its crap when the road is wet (I mean even if its not actually raining, but has been before you go out). The wheel throws road crap all over your pants, which if you happen to be commuting to work sucks.


Its pretty easy to see that its going to throw muck all over you because of how short the mud guard is (seen more clearly in this picture)


I mean it has its up side, which is that when you back it against something its not going to smack into and crack the mudgard (which would suck).

So I decided that a super cheap solution would just be some duct tape.


which is also easily removable when fine weather arrives too.

What I did was stick some on the top that then hung over, then add a little more to that and fold it over, then add some from underneath to have it stuck on both sides of the guard. This has the effect of

  • preventing dirt getting in and needing to reapply often
  • making it just that bit stiffer.
This is actually my mark 2 version because last week at work (where it rained on and off all day) I only had grey duct tape in my car and I wanted black.

While I was planning this, I thought also that the rear guard was crying out for some sort of "corporate branding" (something Mercane seems to have omitted on this scoot, its almost brandless).



You can also see here how far the mud flap extends behind the wheel, compared with how it was before I did this:



While I had it up on the stand (putting on the duct tape) I decided that the front wheel was spraying stuff full time at the join between the bottom plastic cover and the top cast aluminium deck, which didn't look too water proof to me. So


I've extended it up under the arch there too, and as it happens the duct tape is almost perfectly the right width for that cover too.

I put the top arch cover on first, and extended it down into the bottom area, then went across. I also went around the front edge too. Naturally this comes off easily when dry times arrive (and can be cleaned up with a rag and a bit of metho if you're super worried about anything.

While on eBay buying my Ducati decal I also got one for the front too ...


because Mercane didn't brand the goosneck either ...

I think this little bit of preventative maintenance will prevent muck and water getting into the battery and controller area, which can't be a good thing!

Duct tape = $6 for 30 meters (x 48mm or about 2inch) ... should be good for quite a while.
Decals = $5 (who cares how long they last ;-)

So there you go, something practical and something fun.

Friday, 28 June 2019

Mercane scooter: tinkering with advanced settings

Back on Monday (being back in "the big smoke" where its largely flat) I thought I'd try to apply some of the "undocumented" settings on the Mercane and see how it goes. I fully understand why some of these settings are undocumented as it circumvents many of the design constraints put onto the scooter for very good reasons (like preventing you blowing it up because you're unaware of the good reasons).


Cruise Control is found by entering the normal control menu (after powering it up) where you have 4 LED lights (as above, some blinking, some just unlit telling you the status), short presses of the button move it to different modes, showing as 2 blinking white LED's or 1 (red remains blinking), this is indicating if you are in

  1. Eco mode or 
  2. Full Power mode (note: unregulated unlocked mode).
To engage cruise control you pull in the brake, then fully activate the throttle, then let go. The 4th LED will now toggle to blinking or off.

To get to the other version of this where you can control some other (undocumented) features you need to do some gymnastics like pressing and holding the brake and the throttle then putting it into mode change with the longer press. The picture above shows the meaning of the LED's in that sub-menu.

So with that aside I've found that the cruise control is excellent and I like it a lot, however some of the "aspects" of it may not become obvious (and sure aren't documented in the pamphlet "manual" that accompanies a new scoot. I can just briefly pull the brake lever (just enough to activate the tail light) and it disengages the cruise control and I begin slowing under engine braking. Quite natural to "touch the brake" when you're thinking of slowing down.

If you have the scoot set to "Eco" its pretty much that even on flat ground one is going to just press the throttle [thumb trigger] to "full" and when you feel that slight "shunt" (or you've counted 10 seconds) you can let go and it keeps that speed. Remember, a touch of the brake releases the cruise control.

However what you may not know is that if you have it on 2 LED's and hold the trigger somewhere about half and then hold it super steady (I brace my thumb against the plastic where the key is) then you can also let go (at the 10 sec mark) and it will also engage cruise control at that throttle setting.

Indeed I've found that it works at almost any setting where you hold it, even a basic crawl (interesting note: you can hear the square wave of the PWM as a regular "drone" from the rear wheel). Meaning that there is less need for the "Eco mode" now. My observation is that the battery level (which is an excellent indicator of how much power you're sucking from the battery) can be maintained at the same level as Eco mode in cruise control as it can with the limiter disabled.

Not using Eco (and using the above mentioend judicious application of the throttle and cruise control) has the benefit that you can when needed access more power (say a quick dash across a street, aided by an extra kick if you'd slowed down). In this manner you you can then choose to push the trigger full forward and surge away as needed (very hand after slowing to ride through a bunch of folk on the foot path and then surge away out the other side).

You can then resume at any speed by just holding the trigger just where you want it for 10 seconds.

Once I understood this it occurred to me that the ability to over-ride the speed limitation (basically feed in unhealthy amounts of current as far as the battery and probably the motor is concerned) and the judicious use of throttle in combination with the cruise control would give a great operating mode of operation for an advanced rider.

Tonight I experimented with this and found that holding the throttle at about 1/3rd the way in (past where it actually engages) and holding steady gave me about the same cruising speed as full trigger on the "Eco" mode, but with a difference :- I could stab the trigger and it would surge away. This gave me the benefit of rapid acceleration (well relative right ...) that I do not get on Eco (single white LED) nor on Standard (two LED's).

I found this to be very helpful when approaching a medium grade hill to "charge" it (with more speed) before getting to the hill and using my momentum to keep the motor in the more efficient RPM range (these motors are not as efficient when turning slowly).

As soon as I got near the crest I started backing off (just like I would on my motorbike or in my car) and was rewarded by the Voltage climbing back up towards 50.

My view is that if you do things this way you can take some "surges" for a few seconds (and really I don't recommend more than 10) and then resume riding "normally" and take advantage of the power of the motor.

This is not dissimilar to how we (should) drive our cars (or motor bikes) where we apply the right throttle to suit the situation (and speed limits) and do not treat the throttle as an ON / OFF switch.

I'm going to leave it in this mode for the week and see how it goes with respect to battery life. I already have a feel for how long the battery lasts in my "in town" usage, so it will be interesting.

... and now that the week has passed ...

Ok, its Thursday night, done the normal amount of travel and now still at 47V (10 minutes rested after a quick (and fun) dash to the shops for milk). I'd probably recharge tonight, but I'm confident I'll get to work and back on what's in the battery without pushing it too low.

I'd say that the above strategy is working very well for me with the relatively short (say 800 meter at longest) straights and a bit of dash and thrust crossing major roads, waiting at intersections, and general traffic stuff. It has allowed me to reach (briefly) faster top speeds with slow downs (seldom needing much brakes, just engine braking) and using the brake lever as an "off switch" for the cruise control.

I'm quite sure I could not have;

  1. got into my car
  2. driven out of the complex
  3. driven to the supermarket (waiting at lights)
  4. parked
  5. walked into the supermarket
  6. walked out and then reversing that process

as fast as I got there on the Mercane (I was out and up the street before I could have started the car), rode where cars couldn't go and then just walked right into the supermarket after stepping off at the door and pushing it.

Stuff like bunny hopping bumps, kicking off around tight corners (after backing off) and so on is just shit loads of fun that made it even more enjoyable.

Perhaps one day I'll act my age...

Tuesday, 25 June 2019

Mercane Wide Wheel charging port

Just a quick post to show the charging port of the Mercan from the perspective of how its covered to prevent moisture and what type it is.

Basically it is a nice discreet flap made (based on how it feels) from some sort of silicon...


which opens up to reveal an XT60 connector. These are a high amp (60 actually) connector which are often liked for their ease of insertion and their gold plated terminals (see this thread for instance)


Note also the raised edge around the port and that it then sits inside that cover forming an excellent seal. I assume that unless you're a ham fisted dope that just rams it home this will provide excellent sealing for ages, actually looking at the inside edge of the plug it seems someone already had a go at just mashing it down.

I have found that its pretty clear when its seated properly but once you reaslise that rim goes into that groove around the seal and see that it seats, then its all good. After a couple of times using it I find it second nature.

Indeed I've left it just sitting there after unplugging plenty of times with zero apparent issue.

Sunday, 23 June 2019

Mercane Wide Wheels are a benefit

In a perfect world all roads will be like billard tables, I don't happen to live in a perfect world. As it happens when I lived in Korea I found they don't have a perfect world either, so it should come as no surprise that a Korean designed scooter (the Mercane Wide Wheel) is made for real world roads.

On my afternoon ride (which I used to walk, but I really like how much further I can get on the scooter in the short times that the setting sun affords) I came across a perfect example:


and the Mercane just rode along this (I deliberately targeted it to see) without any fuss at all. Perfect, because when you hit something like this (just a bit further along) on a narrower wheel it will spit you off if you aren't prepared.


Anyway, I made it to the top of the hill which is 1.5km from my home in short order, certainly shorter than if I'd walked :-)


on my freshly charged battery. The hill is sort of a torture test in some ways because it climbs pretty  evenly from the end of my street to here an altitude of 32 meters.

Not bad; essentially this single 500W motor is able to climb it and me 32meters height (as well as the trip there.

The view was lovely too.


Saturday, 22 June 2019

Mercane Wide Wheel range testing (bumpy country roads)

I decided to take an afternoon toddle today on the Mercane (after already doing a few km around the town which is actually hilly too). I wanted to test 3 things:
  1. what range it would do on a battery that's had a little load (IE not straight off the charge)
  2. see how hilly areas would effect the range (and using the lower power setting)
  3. how effective google is at estimating ride times when I'm on a scooter and not on a bicycle
I picked a route which heads out of town (the same one I took last weekend on my sunday ride with a mate on an MTB, but to go that bit further. Now because photographs just don't seem to show how steep something is, I thought I'd put it into Google Maps to get the data. This is the ride:


You can see that Google things it'll take 15min and that over the 4.1km the elevation goes up by 50meters.

I didn't check the elevation with my GPS, but I did check the distance and I actually went a bit further than that point, I went around that bend just almost off the bottom of the picture. This has actually quite a steep hill as it curves. Its hard to get a sense of scale from a wide angle picture, but you can see that it rises to about the same height as the gum tree over there (red), and the town is back down on the other side of that ridge (blue).


I had to kick a few times going up the slope (not enough to work up a sweat mind you, just long swinging kicks to just give it that few extra Watts).

Results:

  • My GPS said that it was 4.5Km there.
  • It took 13 and a half minutes to get there but
  • 14 and a half minutes to get back
  • when I left battery was @ 50V (rested state, key on and go)
  • when I got back my battery was down to 45V (after the last leg on the slight uphill that's my street
Obviously on the balance of things its an uphil journey, however the reality is that there are uphills and down hills of different grades on the trip (looking at the graph even suggests this). So even though "going back" is going downhill) there are some steep uphills there too. This is important because a steep uphill will suck more out of the battery than you regain from a longer down hill (where the battery can re-gather some energy by not being loaded up as gravity does the propulsion).

Anyone with a voltage meter on their scooter (few it seems) will know that the harder you load the battery the more the voltage drops (and so too your power), and while the battery voltage recovers when at rest as the chemistry moves around and depleted areas can recover charge from other areas of the cell (complex chemistry but google it if you're keen).

Right now (some hours later) the battery is at 48.1V:


 ...but I anticipate that on tomorrows ride that it will sag pretty quickly on the first steep hill.

So in terms of commuting unless you live in a hilly area (and most cities are built on river plains or costal areas) that you'll get less battery hit for doing essentially 9km (plus probably 2km earlier in the day).

As always, the rest of my posts on the Mercane Wide Wheel can be had by clicking this link or using the topic list on the left.
None the less it was a lovely afternoon ride and I had fun doing that for this "testing"

Sometimes science pays off :-)

PS: I thought I'd add in the next mornings ride to this, where I went up my "torture test hill" behind my place. It started out with the battery at a neat 48V in the morning (so dropped 0.1V overnight, perhaps due to it being cold). So in the few hundred meters of climbing this hill from my place it got to the top a bit depleted.

This is the google maps which shows the hill a little


So you can see that its steep. Here's a quick video.



Because I'm no professional voice over guy (and had no script) and tend to mumble let meadd this here.
[PS: and I've subsequently measured it and its 9°]

So battery now sagging in voltage to 41.2V under load going up there, and I had to (well, chose to) give it a few kicks on the steepest part just before the crest. That's dropping to about 3.1V per cell, which is under load. As soon as you stop it springs back up to 47V which is still in the nice 3.7V per cell range so clearly there's a little more in them (recalling the voltage curve of Lithium)...


and so indeed it made it to the top of the hill described in that video. So if you can tolerate my unscripted mumbling and wind noise here are my thoughts when I got to the top...



As I mentioned back EMF (which I doubt many will know much about, here is a little about that in motors (which I mentioned in my ramble): https://studyelectrical.com/2015/02/back-emf-and-significance-in-dc-motor.html). Basically what it does is to increase resistance (impedance actually) which means that the battery is not having such a high demand placed on it (think of how a short circuit provides a HUGE load on the battery vs a small LED). So when going slow (because of load on the motor, not throttle) the battery gets hammered.

:-)

Mercane Wide Wheel - wheel friction losses

Something I'd like to know (and I guess I'll need to test it side by side) is if the Mercane Wide Wheel scooter (please click this link for all my Mercane Wide Wheel posts).

I've mentioned before that the motors on this type are internal hub motors, but these are no simply a electric stator pushing a rotor in the wheel, they actually have a gear down so that the motor can spin at optimal speeds and give more torque. Exactly like this one from a bicycle (not my video)



So there is some loss in that even when the motor is turning, but when its not powered the loss is a bit more because of that gearing.

Accordingly my Mercane goes down hills with a bit of resistance all the time from that motor (not just from the tyres).

As one who uses this to travel to and from places (home to shops, home to work, home to friends places) I'm actually interested as much in range as I am in "WoW" power. This is because most of my time is spent on relatively straight bits of road / cycle paths.

So I wonder if this Single Motor 8.8Ah battery system gives similar range to the Dual Motor 13.2Ah system because of parasitic frictional losses as well as two motors pulling power.

If you aren't thinking about friction (and wonder where it may come from perhaps in this video we can see (and maybe hear) this:


So this is of course going to be double in the dual motor version (even if power is less per motor, motors are not 100% efficient, thus two will probably be less efficient than one. Sure the Dual Motor has a Eco mode (as indeeed does the Single Motor) in which I'm told the front wheel does not drive at all (in which case it is just a loss).

This is not unlike why classic 4WD's have "free wheeling hubs" that need to be engaged to give 4WD, and can be disengaged to give better fuel economy on the highway (even in 2WD setting).

In my normal use the single wheel is entirely satisfactory (and still a lot of fun) and gets up hills quite ok. This makes me wonder if the AU$1000 for the Single Motor 8.8 Ah battery will have an equal cruising range as does the the Dual Motor variant.

Basically at the time I bought it I found that the Single Wheel climbed a pretty steep hill, faster than I'd be able to walk it, so I thought the extra AU$600 needed for the Dual Motor was better in my pocket than on the front.


Thursday, 20 June 2019

Electric Vehicles Battery Facts (helping make the most out of yours)


Having had a few discharge cycles on my Mercane scooter I've been getting some experiential evidence which (strangely ;-) supports the facts about Li-Ion batterys that I have known for some time at a theoretical level. None of this will be any surprise to a seasoned electric bicycle, skateboard or scooter rider but none the less may provide some value to help you get the most out of that battery pack before it becomes landfill.

TLDR;

Modern folks are impatient, so:

  1. batteries have greater voltage and therefore greater power when fully charged
  2. let it fully charge (at least every third charge) to allow cell balance to occur
  3. discharge more shallow if you can: meaning don't let it get flat as a lizard drinking water all the time, charge it early rather than late.


In this post I'm going to reference two really good articles:

I get that much of that is way more technical than most riders want to get into, but if you want to get the most out of the money you spend on your gear then hopefully understanding these points in my blog post will help.

So lets start with

power and power loss

Electric motors are not engines, they only convert electrical power into rotation. So the less electrical power you have the less "power" your bike or scooter or skateboard has to get up hills (or to accelerate). In electricity power is the simple multiplication of Volts and Amps, so as your battery drops in Volts the power available at your back (or front) wheel drops too. This is the typical power curve of a Lithium battery (note: a single cell):


So you can see that this drops from 4V down to 3.5V in a fairly gradual and linear manner, but falls off a cliff as you go below that. This is important because of two reasons:

  1. you will seriously degrade the amount of life your battery has if you let it go below 3V (and some battery controllers will let it go to 2.8)
  2. power available takes a big dive fast after that 3.5V level which is when you only have 20% of the charge left
Batterys weigh and batterys cost, so all eBike and eScooter and especially eSkateboard makers will want to balance weight - cost - performance very tightly. They may opt for clamping you in a tighter range of the battery using electronics to give you a reported state of charge (some don't report anything, others have some LED dots, others have a full Phone App) that s only down the the 40% state of charge. This is what a "good" battery manager will do, and this will mean you get years out of your battery instead of months.

Now also that above graph does not give voltage above 4V, which seems a bit surprising when a fully charged 18650 cell will show 4.2V on the volt meter when its fresh off the charger. Below is the curve you'd expect from actual battery tests (see this site for its excellent discharge database):



Now note that this is the voltage measured with the cells discharged at 1A and 3A, if you have a 13S4P (see below) pack as in my Mercane Widewheel 500W model that means that to get 1A per cell you've got to be sucking 4A from the pack and to get 3A per cell 12A from the pack.

The voltages are what you can read when its under load, not sitting around, also is why some battery packs are reported as 48V and others 52V. Because depending on what you want to call standard battery voltage the lithium cell in your battery pack may be called 3.6, 3.7 or as much as 4.2. My Mercane shows 52.4V* when its fresh off the charger which is close to 4V per cell (*note: I've come to suspect this is some sort of fault ... either of the BMS or what I don't know, because its not common NOR does my dual motor version do that I have since replaced the BMS and repaired an issue in the pack).

But (if you have a voltage gauge like the Mercane does) we all experience that pretty quickly the Voltage drops to the high 40's (or in that 4 to 3.5 range of linear decline).

So when my Mercane is fresh off the charger (or my mates skateboard) it will climb hills nicely, but when its about "half way" discharged (based on how far I normally travel before recharging) its already noticeably sluggish going up that hill. This comes back to that power equation of Volts x Amps that I mentioned earlier.

  • At 52V (and lets assume 10 amps) I have 520Watts available on my rear wheel (and the Mercane has a 500W motor so that's unsurprising),
  • But as my voltage falls to 46V I have only 460W available. (and this is where I choose to recharge my battery, because like; why run it down if I don't have to).
  • 44V = 440W ...
you get the picture. So those of us who like the fresh power hit will recharge about then, which is usually less distance than the maker says the bike will do. So as I mentioned, I typically put it on the charger at 46V and this turns out to be a good thing for the battery and for my wallet (recharging early).

Looking at the second article we find some interesting points, firstly this chart showing how the batterys stood up with full discharge cycles:


They found that by going the extra distance and taking the battery to "Battery Management System" shut down (meaning your walking) that after 200 cycles some of those batteries had dropped 20% of their capacity from new. At the risk of stating the obvious there's 52 weeks in a year, so I'll leave it to you to work out if that's years or a years worth of use.

This means you'll be walking (or just pedaling) sooner and grumbling about your battery being shit sooner.

The solution it seems simple; charger earlier and only use that full discharge as an unexpected need. They found (presented below) that only discharging as deeply as 60% Depth of Discharge that the battery could be cycled 1,500 times before falling into that failure above compared to a less than half the charges by taking it to the limit each time


... which is about where I take my battery to with what I wrote above of taking it to 46V (or about 3.5V per cell).

this leads me to my last point, which I mentioned earlier and that is the 4V level (per cell) in the first graph. Given that LiION batterys can be charged to 4.2, why not charge them to that? Why 4?

Well again its longevity but to be honest its not as simple as the raw data would suggest. It seems that by charging the cell to 4V (which reduces the maximum capacity by a bit) we get a return in a huge increase in the number of cycles possible before loss.


While this seems attractive it ignores an important point ... we are not charging just one battery.

In the real scooter world we use battery packs (not just a single cell) which are comprised of (around and for example 4 bundles of cells in parallel and 13 of those bundles in series (daisy chain)) to make the humble 18650 cell (which is 4.2V fully charged delivering typically 2.6Ah) into a beast that can deliver 52V and 13Ah ... such a pack is called 13S4P.

The parallel bundles keep themselves balanced (by the physics of being in parallel) the string of series bundles will tend to get themselves into trouble over discharge / recharge cycles (because only in a computer simulation is everything ever perfectly identical). Thus we have BMS systems which actually take care of this, the rub is however the more simple ones (meaning costing less) we usually see in our battery packs do their balance at the end of the charge cycle (moving voltage from the full ones beside the ones slower to charge).

So, don't wait till its super low to recharge ... but don't recharge to full every time it goes below 90% of state of charge, because that will provoke minor eventual loss of storage capacity.Which means that my Mercane will (hopefully) likely give me 3 times more cycles out of my battery pack. This is very positive (yep, you picked it, that's a pun).

Whats in my pack?

This is where its important to know how many cells in your pack not just its voltage, because knowing both tells you about how long your likely to get (assuming the cells themselves aren't crap). Why? As mentioned above,  battery packs are combinations of Series and Parallel, this of course dictates the voltages found.

For instance a 12 cell pack charged to 4.2V per cell would be showing 50.4V and so when coupled to a 48V motor would seem right, right? But equally a 13 cell pack charged to 4V will be 52V and as we've just seen will mean that pack will last more cycles (or years instead of months) and not to mention not die as fast. (*note: in practice this isn't what's done in the vast majority of systems, but I'll get to that).

Die as fast in both ways:

1) run out of grunt (because when the cells drop off to nominal not full it will be 3.7V per cell or 44.4V and your motor won't have the 500W anymore it'll only have access to 444W)
2) life cycle till the battery won't hold much charge (due to excessive electrical wear on the battery).

But this isn't the whole picture

Batteries as mentioned above are really a string of cells (which just like a bunch of chickens) is called a battery.



As it happens most eBikes and scooters have something over 10 and maybe as many as 16 cells in a string to make that battery. Like this:
So if each cell is as mentioned above nominally 3.6V or fully charged at 4.2V then

  • 4 cells would be 16.8V
  • 13 cells would be 54.6V
  • and the 16 cells here would be 67V 

As you can imagine, it would only be in ones dreams that each of those 16 cells (or even 13 of them) would accept charge identically and discharge identically, which will lead to what's called "imbalance" and the pack would soon become unusable.

Enter the Battery Management System (BMS), whos job it is to keep that pack from over charging some cells and leaving others under charged.

Discussing the BMS is actually a complex subject but for our purposes here lets simply it by saying that the BMS starts forcing the "stragglers" to take some of the power that the full batteries have and thus keeping the pack level when its finished.

But (and here's the important bit), it only does this balancing (well lets exclude the high end ones not found in eBikes or Scooters) right at the end. This is important if you're inclined to not fully charge the pack before removing it from the charger.

So if you are inclined to give your battery a little top up now and then (rather than fully charging it) that's not a bad thing, but you really do need to let it fully charge most of the time to ensure your batteries are brought back up to "being full" most of the time.


Lastly while I don't normally feature other peoples work I recommend you watch this youtube presentation on the subject (which I found recently in answering some twit on Reddit)


Its really worth sticking it to the end of that because (like my article above) he starts with the theory first (the ideal situation) and then moves into the practical and then lastly "what he does".

Outcome

So hopefully you'll be able to make what you have last more now and be better equipped with knowledge on the next time you are researching eBikes, scooters or skateboards. Be careful when reading specification (because most of us can't go to a shop and see these things nowdays) and ask some important questions of the maker (like how many cells, what voltage does it charge to ...).

Best Wishes

Tuesday, 18 June 2019

Mercane Wide Wheel - tiny apartment stowage


One of the other things I like about my Mercane is how well it just stows, even in small places.

This is it under the "desk" at my donger *(where I'm living during the week while doing this contract)


Happily I don't need carry it up stairs and its easy enough to just lower the boom and park it under the desk.

Should fit in your office too.

Monday, 17 June 2019

Mercane gets used at home (and other riding notes)

as it happens (for a little while) I'm working in Brisbane but back in Killarney for the weekends, and while I bought the Mercane Wide Wheel to use for getting around the local area (and to and from work) I also wanted it for getting around town.

So we had typical "Mountain Weather" this weekend with a mixture of drizzle, overcast and sunshine. Unperturbed by nature I took it out on the weekend and did some rides. All on one charge, as while steep the town just isn't that big. One could always walk from one side to the other, but then the Mercane is a time saver, where walking would take 20min the Mercane takes 5. Its also just bloody good fun on the way too ;-)

I'll be writing more about this scooter over time, so look over on the left for the "Mercane Wide Wheel" label (or indeed click on the words there as that's a link too :-). This will then open all my posts about the Mercane in "most recently written" order (essentially backwards in time order). You'll find plenty of pics of the scooter there.

Location

So this is a picture from about half way up the southern hill of the town looking north. So you can see that its basically a hilly area with the town in the valley...


... and I live just at the bottom in that nearest run of houses. The field in the middle is where the river goes through and the houses on the far side of the river are were the "shops" are.

Outings

So this weekend I did the following:
  • go into town twice
  • go up and down the hill behind me at least 7 times (over both days) to visit friends and to generally just see if it would go up (among) the steepest hills in town.
  • twice took a run out of town a bit (which is also hilly) the last time with a mate on his bicycle (more on that in a mo)
The road out of town is this one, and its a gradual slope up that a brisk walk makes talking on the phone difficult (because of the breathing).


So basically I rode up this road (note the cracks) and, over the crest, then up over the ridge over to the right and over a few more hills that are out of sight.

Out with a MTB

Interestingly on Sunday when doing this with my mate on his bicycle (who lives near the top of the hill, which is to the left in the above image) as a pace partner, I found that on the gradual inclines I only needed half throttle (yes, you can pick something other than off and on if you're careful) to keep pace, and it was only on the steeper bits of down hill that his better rolling advantage gave him a need to use his brakes (so we could keep chatting and being social, as this wasn't a race but an after noon ride).

Going up the steeper hills I was surprised that he needed to be changing down a couple of gears and even doing a bit of standing in the pedals while I still had some throttle in reserve. I'm not saying he needed to go into "hill climbing" mode, just it was worth his while standing a bit.

Yes, that's right, I could have pulled away from him had I wanted to - up hills. Now clearly he could have gone serious and left me (taking advantage of more speed on his down hills for a starter) but it showed me how good this thing is as a commuter and general "roustabout" and comparable in speed to a moderately ridden bicycle.

He even mentioned that he may get one for his kids so that they can come out when he goes cycling (and they're between 12 and 15) and keep up.

The Steeper Bits

Oddly enough my driveway is about the steepest bit I have to navigate (because my house is on a slope and having a gravel drive), although the last bit of the street joining the road up the hill is steeper. So I get up this by actually kicking to assist the motor (who'd have thought you can kick it along just like a scooter).

Its not too hard and actually only needed 4 or 5 kicks each time, and once over the "crest" of the steepest bit (but still uphill) the motor was enough.

This is interesting because when I was thinking about this (before buying) I expected that my driveway and the end of my street would be the problem areas for it. I did this in thinking about how much energy a good cyclist can put out, which is about 400W and 1000W peak. So I reckoned that (given that) the dual motor would "storm up" while the single motor would need a bit of assist.

Seems that is about right.

Additional thoughts

While one may think that the Wide Wheels are a plain gimmick they are actually very interesting. In the road above with longitudinal cracks the wheels rode right over them without blinking, sure irregularities in the surface cold be felt in the handle bars, but it was nothing more than a bit of steer. I know that my Evo+ hitting them is a big issue (like offing me).

The wide wheels come in handy too when you have to suddenly leave the concrete or asphalt for a car or an errant pedestrian. Being wide they do not just dig in and come to a rapid stop (where you can find yourself falling off again), but cope with the softness of grass and just slow down as if you were using the brakes gently.

I liked that a lot!

Now recalling that this is the single motor model I find this is actually entirely sufficient for a commuter (but probably not someone who's after it as a "wild thing" for entertainment and thrills). Given that I want it for practicality to be sitting in between "walking" and my motorcycle, for trips to the shops, for getting a couple of  km into work in the suburbs each day and for visiting mates in the local area, this pretty perfect.

  • its way faster than walking
  • saves me starting my motorbike up for just a few km (and it hardly gets warm)
  • allows me to go into the shops with it (I put the shopping basket onto the platform and push it along)
The other "considerations" I had when weighing up which to buy were the following points (in no particular order):
  • The open front wheel (because no motor) provides a convenient location to lock the scooter up "outside" in those places where you can't or simply don't want to take it inside.
  • the wheels with motors do not spin freely while the wheels without motors do, so when I don't need that extra power I am having to power that extra motor (and fight the friction of the gears inside, because while its a hub motor its also got planetary gears, see video below)
  • having that extra power would probably encourage me to push it harder and go in rougher places, which will reduce the life of the scooter. I also have an economic thread in the fabric I'm weaving here.
  • While the dual motor has more batteries (helping with that range issue), its also heavier, which makes lifting it in and out of the car / house harder.
  • I got this one for AU$1000, which was AU$600 less than the dual motor, or put another way the dual motor scooter was going to cost me 60% more, but still be the same speed on the flats (speed limitation) or suck batteries harder (if I unleash the limiter).
  • These things just aren't motorcycles, and so on open roads a motorcycle is faster, on foot paths you mix with pedestrians, so it is a compromise.
  • The smaller battery charges faster than the bit one and as I did this whole weekend on just one charge I consider that's a benefit.
So right now I feel like that Single Motor Mercane Wide Wheel has been an excellent choice, its a compromise (and what isn't) and for a person who wants a low end electric vehicle to get places which would be on the verge of walking (and yes, this thing is not a toy kids scooter with a motor on the back, its a genuine vehicle) this is fantastic and better than anything else I've seen in the category of single 500W motor.

I think its win win

I'll leave you with this shot of my scoot at the summit of the local hill on Sunday Afternoon



This is the top of the hill at the back of town (and I live at the bottom of this hill) and it was nice to get up there and watch the sunset.


Thursday, 13 June 2019

Mercane Wide Wheel eScooter (the "Cadillac" of electric scooters)

I decided that while going under 2Km on relatively level grounds that my Evo kick scooter was fine, but that when going further afield all that kicking was getting old (like me). What I needed was a bit more assist (read some power) because I'm not getting younger (and nor are my knees) and lets give hills a mention too.

I've of course seen many of the eScooters around (hello Lime) but having some amount of experience with scooters (starting 10 years ago) I know that bigger wheels means better wheels.

Now while the little Evo I bought (mentioned in my previous post here) is doing the job (with those crap bearings replaced) its still a little restricted and probably a little unsafe (brakes aren't that effective, and from experience worthless if any water (from rain, a puddle or snow) is on the wheel. The Mercane solves a lot of this.

Closer look

When looking at the options the Mercane came up in my searching and it looked quite the good item, well made and effective.

Its not till you actually see one in the flesh that you go WoW

Now there's plenty of images on the net to look at (and I'll add something from the Mercane site at the end) but I thought for my first post on this scooter I'd just show you some images which I hope will put in perspective how this thing is a entry into Electric Vehicle not a borderline toy.

So for those who are considering this as a commuter (and may have some experience with the sorts scooters on the market),this is it beside my Evo. Both have about the same diameter wheels, however the Evo is under 4kg (and an easy carry) while the Wide Wheel is about 17kg and a bit of a heft.


This heft (and the wheels and the suspension) translates the Mercan from "a twitchy thing" into "a confident stable ride".

Storage

Back in the office (or in your flat) the little Evo tucks nicely under a desk (or in a closet) but the Wide Wheel may attract more looks in any more crowded open plan office (and won't fit under the bed either).



But its far easier to store than an eBike ...

I've long been a fan of bigger wheels on scooters not only for bump handling but for not being "stopped suddenly" by a small bit of rock, other crap on the road or even an out of level pavement block. The wheels of the Evo are a bit bigger, but when you consider the width and cushioning of what are very similar to pneumatic tyres (but aren't thank god), the Wide Wheel (with softer pliant tyres and suspension) is just orders of magnitude smoother over stuff on the footpath or cycle way.



Its clear that while the Evo has bigger diameter, it will still get snagged in any cracks between concrete pavements on the foot path or longitudinal cracks on the road, not the Wide Wheel though.

I say almost pneumatic tyres, because they are not quite, they're like this *(obtained without permission from the Mercan site):


which is essentially half way between a solid and a pneumatic because it has a rubber skin like the penumatic and a softer foam for a bit of bump compliance underneath. The foam provides some "give" and the rubber is ... well ... just like a tyre. The feel of the tyre give (when pressed with my thumb) is about equivalent to a mountain bike tyre inflated to 40psi (270kpa), which myself I find is good compromise for ride VS rolling resistance.

That diagram shows the brakes, so lets have a look at that on mine. The disc on the rear is more than up to the task and unlike the friction of pushing down the rear metal mudguard onto the plastic tyre of the Evo is predictable and dependable even with a little moisture on it.


So absolutely nothing to complain about here. Indeed if you lean back (transferring your weight on that rear kick up support there) you'll stop even faster because you can transfer your weight almost totally over that back wide wheel.

Now as the deck is alloy (and beautifully formed) that "kick up" at the back is also alloy and very study. Its actually an excellent place to put your foot on (always ride with one foot foward the other back on a scooter, not feet side by side ... you'll balance better that way). This provides an excellent feeling of balance and support when the motor starts.

But unlike the little Evo this isn't the brake (but if you're used to scooters it'll feel right at home having your foot on it.

The next thing I'd like to mention is found in the exploded diagram on the Mercan site:


The above diagram is actually exactly my bike (with one small exception), as I have the single motor 8.8Ah battery variant. Aside from the fantastic build quality and suspension system this diagram shows something that every Xiaomi 365 owner will eventually attest to: changing a tyre is a fucking nightmare. Now while I have not yet done it (come on, I've only had it 2 days) notice that the rims are split down the center into a left and right? I imagine that will make changing the tyres so much easier when they wear out (and being solid won't get punctures).

Handling

I have once or twice seen mention of the fact that as you corner harder you'll experience a strange "resistance" to the bike turning. This is indeed because of the width of the wheel and the profile of the tyre. In practice you may not notice it, but as soon as you want to do a U-Turn you will. The bike fights you as contact patch of the wheel moves further away from center (take a look at the above shot again showing the wheels).

Now the answer to this is to lean your body further into the corner (keeping the bike more upright). Actually on a scooter this is a good idea also because if it "slips" (like I've had happen on the little Evo) you're prepared with your foot out ready to kick and restore grip. I'm not sure that such is going to happen at 20km/h but none the less ...

I've read (presumably from people who can't ride a motorcycle) that turning it is done like turning a motorcycle, where you lean. While not even slightly correct (you don't turn a bike by leaning it but turning results in it leaning) its good enough for a non rider to "get the hang of it".

Decisions

now everyone needs to balance how much they are willing to spend against what they want it for. For me, this was more about an effective transport than a "fun" machine. So while I do want something that can get up hills (who doesn't) I also didn't want to spend nearly 50% more on the scooter just to get the more powerful (and then require the bigger battery too) if this would do my job (and be legally compliant).

When I went the sellers place (BZooma on the Goldie here in Australia, whom after sales has been an utter disgrace so I DO NOT recommend them) they had a substantial hill just across the road from them. I was able to climb that and still go faster than I'd walk it. Better yet, I stopped on the middle of the steepest part of the hill and was able to kick and go and continue climbing.

That sold me on the scooters ability and only time will tell if that was a good test. But when I get back home to where I live I'll be testing it on more substantial hills and I'll report then.

Conclusion

So right now I'm really stoked about this scooter, its doing everything I expected of it and that I only paid about AU$1000 (instead of about $1600) is fantastic.

I'll be reviewing more in time, so look for this tag label (Mercane Wide Wheel) in the left hand side.

Enjoy

(PS, I mentioned the seller I bought it from because they were so good to deal with. I believe strongly in the "Invisible Hand" of the free market and so my mention of them is totally my choice and totally un-rewarded. I have nothing to do with them except buying this one product).

Sunday, 2 June 2019

Unconscionable components decisions make good products into junk

Back in 2009 I had this particular model of folding kick scooter for getting between office and train, it was great and I used it all lot even on weekends.


Having long since gotten rid of that scooter (changed countries, different needs) I came to find myself again in need of a scooter for a similar role. I was pleased to find the same (or almost) one still available for a reasonable price at a variety store in town. Having had such a good run out of the last one I was pleased to find a new copy of my old friend.

However things were not so good this time round and the scooter had a rear wheel bearing collapse in just 3 days.

WTF!


By two weeks the front wheel bearings were in a bad state too, and in the verge of collapsing too.

I got new bearings off eBay for just 70¢ each.




Makes me wonder just how many of these scooters became landfill in a week because of simply cheaping out on such a trivial part?

(minor yet effective) fireplace improvements

It has appeared in the background of some of my blog posts but, particularly in winter, my small wood burning heater features at the center of life inside at night.

Like all things, almost nothing is designed for Australian conditions (even much of the commercial stuff here which is often just slavishly copied from Northern Hemisphere conditions). One such thing is my wood heater.

Its a fairly ordinary heater for its type (and already seen a bit of use too) and its about 60cm square with an inside compartment about 40cm deep behind the door.


So while not big, is certainly big enough for the room its in (and my adjoining bedroom).

It has an added "benefit" that it has a small electric fan that sucks air (you can see the grill at the bottom and the switch and lead on the right) from the floor and circulates it through the back of the heater and comes out the vent at the top. This can really help warm the room faster, but its best not left on long or it will strip heat out of the furnace too fast and result in incomplete burns with Australian hardwoods (design issue #1).

Actually Australian hardwoods like Eucalypts (or known locally as gum trees) are harder and heavier woods than the common northern hemisphere woods (like pine, birch or spruce) and require much hotter temperatures to get going. As a result they burn into coals more readily and long after the large flames have gone there remains intense heat coming from the mass of coals.

Unless the furnace sheds the heat too fast, like the fan tends to do. If you use the fan too long you'll rob the system of energy needed to sustain combustion, and you'll have heaps of unburnt charcoal left in the morning (and the temperatures will fall sooner).

Its also actually difficult to start hardwood burning in these furnaces and requires (more) tending (than I'd like) to get the fire going. Not least of the issue is that it does require more air flow than softwoods require to get going and stay going.

I've noted also in my fire stoking this last winter (southern hemisphere, means its winter here now folks) that the coals burn and crush under the weight and choke the air flow and thus the heat coming from above (which is the wood).

Having seen a few hearths in my time I've noted various attempts at making a fireplace cradles to hold the burning wood and coals and achieve better air flow (ash falling away).  While in some ways in a fireplace they are also designed to increase radiation, in a furnace like mine its un-needed.

I've also seen gates held up above the floor of the furnace, but they are also make it a pain in the arse to clean the furnace out. My furnace is easy to scrape out with a small shovel.

So I came up with this idea, some simple lengths of 50mm box section which contains the coals, allows air to pass beneath the log and through the coals and no matter what allows some air to get to the back of the furnace (and the hot air exits the top from the front too).



In this photo above you can see that I've cleaned the floor, left the larger unburnt coals (and actually now with this system there really are less coals in the morning and more ash - meaning better completion of transfer of energy from the wood into my house).

The one on the right looks odd at first glance because it has a 45° cut in it and I'm going to weld on a short section to prevent logs rolling off the cradle (and snuffing out). This will still leave the bottom open to carry air through.

This also makes it easier to start with a mixture of woods too. I'll start from the bottom:

  1. coals from the previous night, with wood splinters and some small off cuts sprinkled atop the coals (from checkering the slats I put on the house (earlier blog post) (waste not want not).
  2. two small chunks of fire starter (hexamine), each is about ¼ of a piece as it really starts quickly
  3. a layer of pine (scrap 4x2) cut into small sticks and to act as a pyre and get the coals going too
  4. cross angled shorter pieces of 4x2 hardwood (gum) scrap wood (I got this from a re-roofing done locally for free) which will then fall (burning) onto the coals when the pine is gone
  5. a chunk of hardwood of medium size to get the ball rolling.

This will go for about an hour with what you see and bring my room up to 24°C when outside is 8 or so.

So if you're an Australian (or Kiwi) using Gum you may feel free to try this design out and see what works for you.

Oh, and the steel was sourced free from a local guy making cattle races.

Win Win