Tuesday, 30 July 2019

more vs less (what I think so far)

So, its been just a few weeks with both Mercanes (or a bit over one and a half months with just the single wheel) and I've found that its a mixed bag of good and "issues". Let me put my thoughts together on this:

Single rear motor

the good :

  • I like the moderate but sufficient power delivery. Its not enough to put you and keep you off balance and sufficient for most hills (except the really steep ones, to put a number on this 5 degrees and it'll struggle 4 degrees and it'll do it). Personally I find up hills I'd prefer to be on the Mercane than a bicycle (except when fitness training)
  • its lighter (at least 4kg and the front is much easier to lift) making it easier to carry and lift into the car. Its at that weight where another 4kg moves it from heavy to "ouhfff")
  • it has less "friction" in moving it around when (say) in the supermarket because the front wheel has not motor and rolls nicely (see this youtube video showing wheel resistance) 
  • it has better clearance underneath as the battery box and single controller is more snug
  • it is light enough to get a small amount of "air" when attempting to jump obstacles such as nasty pavement joins
  • it steers very neutrally and is easy to learn to be confident on it
  • the brake is best described as quite adequate (unless you're attempting to speed through crowded areas or places with low visibility)
  • charge time is less

the issues:

  • you'll need to kick (or get off) on really steep slopes ... getting off is a good option as that will return far more battery distance than the 10 meters you stood on it for
  • its not "exciting" acceleration (which may be a hidden good)


The Dual

the good:

  • man does this thing kick when you hit the throttle (starting off) and it hits its top speed much sooner than the single
  • it just motors up long steep hills that the single will struggle with (and probably you walking would too)
  • somehow the dual gives more distance than the single does (as u/InfernotTerror mentions) which I suspect is because that while it will use more power on the hills (like say up to 1000W) the speed limiter will on the straight mean it uses only about the same power as the single does, and you have 50% more battery (which will probably give more than 50% more discharge)

the issues:

  • its a lot heavier than just picking up a 4 kg extra may sound. Many will struggle to lift it into a car boot, I certainly don't like lugging it into the house, and glad I have a wagon
  • the underbelly hangs low and so you have to be careful when lifting it over steps to not drag that belly pan
  • torque steer (which may be contact patch geometry issues ) is very noticeable, the more the steering is off from straight the more you'll feel that hit on the bars as it tries to fight you. You do get used to it, but it will require you to focus on that.
  • front wheel loss of traction will occur far far more than on the single because the front motor is pulling just as hard as it can and you will weight transfer back because of that (unloading the front, reducing its grip) unless you remember to lean forward. This is definitely a scoot that reminds you that you MUST use body English on these things not just stand there like a passive statue as suggested in the promotional material. This will undoubtedly lead to more stress on the steering stem over time too if you just use that lever as your balance pole. When the front breaks away (say, entering a driveway that's firm fine *(think tennis court) sort of gravel) it won't be coming back (even one reviewer had some fun with this)


So I think that summarizes it ... so now, I'll get out and ride ;-)



PS: I've finally done the video comparison of the uphill journey over to my mates place, its here.

Sunday, 28 July 2019

Motor temperature

Longish ride (about 6km), lengthy hills, cruise control all the way and set onto "power" setting.



No problem :-)

Saturday, 27 July 2019

things that go bump in the night...

During the week I live in "the city" and come home on the weekends. Surprisingly (although I live in a rural area) the footpaths (that's sidewalks for Americans) in "the big smoke" are shitloads worse than they are here in the countryside. Here are some examples of what I encounter every day:

I photographed this during the day, but experienced it first at night. It was clear that my OEM headlight was barely up to snuff, so I got a brighter one. Stuff like this looks innocent to anyone used to riding a bigger wheeled (and thicker tyred) bicycle:


... and you may be tempted to steer around that puddle, but when you look up close you'll find the reason why when you did, that on your scooter you heard that loud "BANG" when you hit it.


Yep, to your tiny 8 inch wheel that's a rather large whack it's going to get.

When you start looking around you'll see more of them...


and


as well as cunning shit hiding in places you just won't see:


Classy...

So if you were on a scooter like a Xaiomi and your tyres weren't pumped hard, then there's every chance that when you hit that you'd be walking home (and or late to work) and then joining the legion of sufferers who are going through "changing the tube hell" (google it).

This is exactly the reason I picked a scoot with non-penumatic tyres like my Mercane.

Now if you (as do I) commute home in the dark often enough sometimes you miss this sort of detail  and then you'll eventually (despite every endeavor) hit one of these bumps and hear that "BANG" as your rubber tyre absorbs what it can, and your suspension tries to give a bit too, but inevitably your tyre and rim will squeeze that tube to a pinch and its leaking. Inevitably however you'll find that some of the hits will leave a deeper mark (if you bother to inspect your rims that is).

So far I've had some doozies (because I live in the bum-hole of SEQld; where maintenance is irrelevant to a bankrupt council)

Eg this one which clearly flattened the rim a bit:


and this one which went "full on" in impact ...


but being exactly on the support "spoke" couldn't just bend the rim ... and you know when you look at it I felt that one don't you ;-)

If I was on a Xaiomi that would for sure be a "walking home" ding.

As well there have been sharp stones which have put cut marks into my tyres which would have been punctures for sure


and this one which was probably a pinch as I went over one of those concrete bits at an oblique angle



And so?

Now none of this has stopped me, delayed me or prevented my scoot from keeping on keeping on. Yep, no flats, no down time, no late for work, no pushing it home, it just keeps on going.

Eventually that rim will need to be replaced, but when that time comes, I'm quite sure that doing so will be

  • less difficult, 
  • less expensive and 
  • less time consuming...
than all the fucking flats I'd have had in the last 2 months of scootering around the shit roads of Logan City. Eg this thread on reddit is just typical.
Spent 2 days and over 6 hours trying to fix and replace a tire on the M365. They made it practically impossible to do, I have looked at some youtube videos and they make it seem like its way easier than it actually is to replace it. Does anybody have any tips?
So exactly as I anticipated at the start: pneumatic tyres and small wheels is a bad combination.


Now its worth pointing out here that the Mercane has quite soft and pliant surface rubber (unlike the implication from people saying "solid rubber"), which provides excellent grip even in the damp. In fact I'm sure that half the reasons why those puncture (of a pneumatic) type penetrations have occurred is because its soft pliant rubber ... but because its a foam filled tyre it just keeps working.

Now, keep in mind that the force of impact = the mass multiplied by the velocity squared (yes squared) so this means that for every small increase in speed the force applied when you hit a bump goes up much much more.

If anything it might be nice if the tyres were a bit thicker ...

Friday, 26 July 2019

insignificant niggly shit that's gone wrong with my Wide Wheel

I thought I'd put together this page that I may update as more surfaces of the niggly details I have had from delivery with my two Mercane Wide Wheel Scooters

Lets start with the first one, the Single motor

Aside from there being missing screws in the base plate (which a text to the shop rectified, and they posted me them) I found that the side covers to the swing arms were loose, so as I was pulling out screws to loctite them (I strongly recommend this as otherwise you will loose some) I took them out of the side covers and examined why they were loose.

The reason turned out to be that the parts where the screws held them into the swing arm had shattered, and this was how it was on delivery. Luckilly the bits of plastic were all there and I was able to glue them together as seen below:


curiously though that pattern looks like this was actually 3D printed and indeed the crappy plastic makes me think it may have been ... it really is brittle plastic and while the accuracy of casting and fit is good, they just won't last as they are with this plastic. So I also used some silicon to assit holding (just a few bits around the inside of that plastic to hold but not make it impossible to remove)

Then move on to the second one, the Dual Motor

The grip area was covered with a bit of cardboard, and when I was peeling the tape off the kick board it just lifted a bit of paint off ...


So far it hasn't spread but I think this is shitty and indicative of a poor paint preparation (you can see the alloy underneath has not been etch primed before painting by the crystal shapes)

The dual motor too had some pre-broken swing arm cover mount points, but the plastic was different, more flexible. None the less I've siliconed them on too.

The grip area was not well applied (as visible above too) and I pressed out some bubbles with a roller and the standing on it (and sun) has ensured it sits well now.

So far that's been it for me, which all in all is not significant and for the price for what you get I'm totally comfortable with this, although I've read on the internet some other issues others have had.

Feel free to comment with your issues and links if you can to where you've written it up. Please note that this blog is moderated and so comments will not be published before I've reviewed them and comments containing nothing more than advertising or spam will be deleted. I don't do ads on my blog and so neither will others.

Best Wishes

Wednesday, 24 July 2019

Mercane Motor Heat

a significant issue in longevity of electrical motors is how hot they get, so I thought I'd start looking into thermal issues (why not? ... its a good excuse to go for a longer ride on the weekend ;-)

So this is a shot I took showing my thermal image, sorry, but try as I might I couldn't get the camera to focus on thermal imager (if I had three hands maybe...) but it was reading 35°C here after a long steep uphill run. Ambient air temperature was 23°C


you can see its warmer than the (about 7°C temps from overnight on the back of the water tank here) ambient, and that the hottest part was the part of the tyre which had been in contact with the road.

And the front


I'll try to get better shots this weekend.

However while I'll need to wait for summer, I feel that this indicates that I could push these motors to a bit higher voltage, because this sort of temperature isn't even significant.

(*you'll note its pretty dusty because its been on a few rough dirt roads)

I've done a slightly more lengthy follow up here after a much longer ride.

Sunday, 21 July 2019

battery compartment preventive maintenance

I have often stitched up my clothes and I can attest to the correctness of the adage "a stitch in time saves 9"; so I decided to do a bit of quick maintenance on my Mercane Wide Wheel (dual motor) while I was pulling the cover off for an inspection of battery (for evidence of heat damage, and I found none).

Basically I found that the battery is actually held in place by that bottom cover, so its actually important to not break it (because it serves an important purpose too). I also observed that the battery is already sagging (well why wouldn't it) and putting weight on the wire that runs underneath it (see video). So I decided to give it some additional supports (other than just pressing on the wire).



While I was in there I actually noticed that there are holes in the bottom of the base, which is a good thing as that's going to help ventilation and allow water to drain. I'll have a closer look at my single motor one when I get back to Brisso tomorrow.

Saturday, 20 July 2019

Mercane Dual Motor Torque Steer

I currently own both the dual motor and single motor Mercane Wide Wheel, I leave one down where I work (200km from here) and one here for the weekend (saves hauling one around and that seemed a valid excuse to try the other when I bought the single wheel first ;-).

Which is better?

It turns not a straight forward question of money vs power (although on the surface it may seem to be).

One of the major differences is that the dual motor has more torque (like double heh) works out to be plenty for hills with my body weight. In fact for all but the steepest hills the single motor works out to be sufficient (meaning that if you're not seeking thrills then it does the job quite well). I mean looking at this trip, I would doubt that the dual wheel would bring much to the table in terms of getting there and back in any significantly shorter time. Interestingly I found that going up the steepest parts of the steeper hills that kicking made a difference on single motor Mercane but curiously it didn't do anything on the dual motor Mercane.

Now part of that is probably that its going almost as fast as I could possibly propel any scooter with my foot, but it feels like I'm putting in substantial energy but that's being absorbed by something. My suspect is the extra weight and the extra resistance provided by having 2 motors instead of 1 (and a very low rolling resistance front wheel).

Weight

The dual with its extra motor and 50% more battery (and extra controller) weighs about 5~6kg more and you do notice this lifting it in and out of the house. I don't think I'd like to lift the dual in and out of the boot of a car, indeed I could barely get the box out of the back of my wagon by myself when I got it home.

Handling

Then there's torque steer, the dual wheel has a substantially observable change in steering reaction under power compared to the free wheeling front wheel. I've noticed that almost nobody (even motorcycle riders) seem to get what's going on in geometery, so lets look at this quickly (and you can read this link if you're interested (which you should be).

Basically the front wheel of a bicycle (scooter, motorbike, whatever) has by its steering geometery built in stability by the same way that castor wheels work on chairs, shopping trolleys you name it. This is clear on a castor wheelsbecause the wheel is clearly behind the bit that spins, but on a bicycle perhaps not so obvious and its done like this:



So on a scooter, the smaller wheel makes the geometery harder to see but its still there.

Now when you have the front wheel pulling, especially when in a corner things get interesting because suddenly there is another force on that wheel pulling the castor around.

Unsurprisingly this makes the steering want to follow the straigh line and you feel that kick in the handlebars quite strongly. I would liken it more to front wheel drive vs rear wheel drive in the pre power steering days, but I guess younger readers just won't even know what that means.

However in a straight line, belting along a flat grassy field (heaps more resistance than the road in case that didn't jump out at you) the dual wheel just hoots along at 21kmh, while the single struggles along. When climbing my drive way the dual wheel power provides some great benefits by not just spinning the back wheel or causing the front to lift ... so its swings and round abouts.

 As it happens I'll be needing that this weekend when I'm doing traffic control at an event up here where I live.

Sunday, 14 July 2019

Mercane Dual motor underbelly

being one to always like to look under the covers (as well as check all the screws) I decided this afternoon to to pull the cover off the battery pack on the Mercane and have a look. Compared to the single motor its quite "pregnant" under there. Basically everything below the red line is unique to the bigger battery system of the dual motor.


Its certainly made the whole thing heavier, with my scales suggesting that the weight is actually more like 23kg. Interestingly it has a front rear weight distribution which puts 14kg on the front and 9kg on the back (bathroom scales under each wheel and confirmed with my digital luggage scales and also with my holding it and getting onto the bathroom scales). Update: my single motor variant is 11kg front.

Interesting.

So what's under the cover?


In this shot we see that the battery runs the full length of the available tray, as well as the wonderful webbing cast that strengthen that entire platform and the controllers.

plural you say?

Yes, two controllers, stacked one atop the other and thus hanging down lower than the battery pack.


as well as seeing where the plastic belly pan screws into we see the location two controllers. Which is interesting and confirms my suspicion that the way the dual motor version was implemented was to just double the controllers and bung on a back wheel on the front with its own controller. Simple and quick upgrade, run some more wires and voilla. Indeed that cable that powers the front wheel jutting out of the goose-neck at the front sticks out like an after thought to me when I think of it.

The basic maths on the controller is that being rated at 15 Amps it can handle 720W which is more than the peak draw of each motor, so there is built in margins there, which is nice.

Now its interesting to look at these controllers and observe that they are passively cooled (fins give that away), given how much heat controllers need to shed (from switching as much power as they do) is this a bad thing in an enclosed and sealed case? Perhaps, lets recall that the Wide Wheel has its origins in a indigogo campaign (link here) and when it was envisaged it was a single motor design.

Now owners of Mercanes may have noticed this set of 4 bolts directly above the controller ...



I understand that this is for a seat (I'd feel shame) ... none the less mounting the controllers up against the chassis looks to me a very tidy way of making use of that big cast aluminium frame as a heat sink. Cunning and well designed!

So it would appear that the original single wheel version planned for this from the outset, but the dual motor version just whacks that controller onto the bottom of (not a big heat sink) but the other side of a hot controller.

I'd hope that this was tested before being done, but somehow I have some reservations. Indeed I've seen examples of burnt out controllers on the dual wheel on YouTube already (by perplexed non technical owners).

I dunno ...

Anyway, moving up front we see more clearly that lovely webbed cast plate which is the main chassis of the scooter. It actually looks fantastically well designed and made. Looking at the lip around the bottom of the chassis you can see that the belly pan fits snugly into that. However also you can see that any water throw up from the front wheel will be likely to gradually work its way into that crack and down into the belly pan (where there is no way out). This is why I put duct tape over that join to prevent such (as I've owned old English cars in the past ;-)  (post on that here)


as well we can see the underside of the XT60 charging port (so clearly no problem if a little moisture found its way in there past the plugs and cover)as well as one of the belly pan mounts and holy moses look at the bracing around where the goose-neck mounts.


I'd have to pull it apart to see, but it looks like the goose-neck goes down into there and mounts somehow. I'm keen to pull that apart and look (especially after seeing a few Zero's bite the dust exactly due to insufficient engineering there (this is a shot from the internet):


as an engineering sort of guy that even looks inadequate before it broke. Sure, the front part looks solid, but you know what they say about the weakest link in a chain right?

Round up

Well that about rounds up what I've got to present tonight. The Mercane chassis looks great, I love the way the controller uses the chassis as a heat sink, but I have my reservations about the piggybacking of the second controller down there.

Then theres the weight ... its a lot heavier to heft around than my Single motor version ... which to me is shaping up as the sweet spot of the design (and indeed closer to the original conception of the designers. As I see it the original concept of the single engine 8.8Ah battery is not only sufficient (as I've already found) but robust.

I'm starting to feel like the move to dual wheel was more about being seen as "not competitive" in a market which is more interested in bling and "hot looks" than in good robust transport.

So basically I'm saying I'm thinking of seeing if I can send the dual motor one back and sticking with the single ... but then again, maybe I'll just keep it longer. Besides, its convenient to have two right now.




Saturday, 13 July 2019

Mercane Wide Wheel dual motor up the range a bit

So with my first day riding around on the 1000w dual motor version I've been experimenting with what I can do with that extra power (aside from just simply go faster and hurt myself or maybe blowing it up as I mentioned in my previous post). Hill climbing is the obvious answer, and so I rode out of town and went up here for a quick test. The ride is done on the "Power" setting (but with the speed restricter re-enabled because I just don't want this to be a weekend wonder...


The stats on the journey are this:


You can see that I didn't actually go back to my starting point, I instead went to a different place in town to visit a mate.

However this time it climbed 184 meters and I hit a maximum speed of 40kmh (probably on the way down the mountain).

Here's a bit of video I started after I was out of town just before starting the main climb up to Daggs Falls



So theres some incoherent ramblings about stuff (you can tell I don't script this stuff right?) which does however show how well the bike goes up ... and up ... and up

And of course then there's down...



My views on the increased rolling resistance of the motor (vs the wheel without the motor) and that the wide wheel having two motors will have more resistance may actually be a great benefit on steep long descents like this because I didn't actually touch the brakes.

So ... probably something tomorrow too

Friday, 12 July 2019

Mercane Wide Wheel: benefits to more power?


I've struggled with this idea for a while and decided that while I don't really need more power most of the time (and I doubt it will significantly influence travel times) that I just wanted to try it.

So while my Mercane Wide Wheel (500W) single motor is "perfectly sufficient" I decided that I'd try out the 1000W dual motor model (yep, one on each wheel).

In my explorations of the 500W model I've found that the cycle calculator I've been using suggests that by adding a few more watts I can get up the hills in my area with no slowdown. My calculations show this (I say mine, because I've had to tweak my parameters based on measurements):


Note: the 8% grade is actually about the standard for a wheel chair ramp. My hill is 9degrees which is 16%.  I picked 21kmh as this is pretty close to what I've found the speed limiter kicks in at anyway. Meaning that I could be going along a flat, and as I approach a hill it can increase to as steep as 8% and the scooters cruise control should just compensate by turning on more power.

In theory the scooter is able to provide 1,000W (sustainable, lets not go into peak), however as I've mentioned before as the battery voltage buckles under strain (batteries are not like regulated power supplies) down to 47V (which I commonly see under load and half way through the discharge cycle (see this post) that means that each motor will be able to deliver more like 450W to the ground (cos like nothing is 100% efficient right).

If I'm right then this means

  • the batteries will not be being hammered as hard on hills
  • flat roads will still be limited to 21kmh by the computer system
  • and down hills may be a bit less fast in peak speed due to the extra resistance of an extra motor.
So, all things being equal I'll be testing this tomorrow and will put in a video under this line to show findings.

Fingers Crossed :-)


Ok well I put my GoPro on and dragged it out of the house for its first start up. I had not run it (meaning fresh out of the box, over night charged) before this, so it was as fresh to me as it will be to you.

Just a warning, some "Aussie Guy" sort of language involved


Summary


  • Hill climbing power is WOW, the "pinch" up the last bit of my street before turning into the other street is 9 degrees (yes, degrees)
  • man, does it hammer that battery down if used unrestricted (wait for the comment about unlimited in the vid)
  • build quality is still excellent
  • change of surface coating materials may have it looking less beautiful with wear
  • observable torque steering, which makes for a surprise and can drag you off line on a corner when you "hit the power button"
  • a little lower clearance
  • a significantly heavier ... I notice its heavier but its still OK (just) for lifting in and out of the house. Car boot I dunno ... my wagon is fine thou
So, in short fuhhken great mate.

I went into the "hidden" settings and found that it had been set with speed restriction off, so I re-enabled it. My view is that this is not just a good and sane mode for operation (and legal compliance) but will enable you to get anything like decent distances out of your battery and (importantly) not fuck your battery as I see many have done to their scooters on Reddit by disabling exactly these features.

Disabling this is a bit like running Nitrous into your engine ... sure it'll surge like nothing on earth, but it'll be stuffed pretty soon.

HTH

Wednesday, 10 July 2019

the same shopping trip in the car (compared to the Mercane)

Tonight I went to the same shops in my car as I went to on the Mercane Wide Wheel last week. I thought I'd use the GPS Tracker software to check that journey. It was interesting because (as you see on the map) its actually shorter on the back roads than on the highway.

For reference here is that trip again:


Although I didn't go to that point I went to the shops just a bit further to the bottom. This is the stats from driving home by the freeway in the car:


and to refresh this is the stats on returning home from the exact same place by the scoot last week:


obviously there are some minor differences in what the GPS thought the altitude was and such, however the times are interesting:

  • 12:48 in the car
  • 20:51 on the scoot
which is about 60% faster.

This may not like much of a competition (if we were racing) but in the reality of transport and transport costs the scoot would sure as shit beat the bus or other public transport.
Also, looking at the speeds, if it wasn't for the highway enabling me to be over 65kmh for a fair portion I reckon that the difference would be much smaller. Meaning in suburban transport situations the scoot would be much closer in time.

discussion

There is a classic example of transport speeds given in computer science that involves walking, bicycle, cars, trains and air craft. Its designed to show that there are distances and speeds at which going faster just doesn't bring much to the table. The eScooter has stood out to me from the time the moved out of kiddie league into the 500W area that this would be true here too.

To me anything under 5Km and its a "hands down" choice to take the scooter (unless its raining) because it will be faster (especially factoring in getting out of the secure area where my car is), not least because of short cuts and avoiding traffic. Equally there are distances I just would prefer to use my car over (and if its raining ;-) such as my 200km drive from my town to the city where I work at the moment.

The scooter sits in the back for the  trip down and gets used around town so the car just does the highway trip.

This has an added bonus (to me) of not actually contributing to the air quality issues present in the city by minimizing my car usage in a place where there are litterally millions of cars. Even far more than electric cars the eScooter further reduces emissions because it uses far far less electricity per trip because its so much lighter.


Very nice

Sunday, 7 July 2019

Charger sparks

Some question recently about charging and chargers and when and how to plug your charger in to your scooter prompted me to write this. The short answer is » plug your charger in first.

This is a closeup of the XT60 plug my scooter has for charging. You can see the evidence of powerful sparks arcing across between the charger and the battery in the burns and pitting happening on my plug:


And



So "why is it so".

Its simple really, its potential difference (you know what we measure when we measure voltage). If no difference exists then no current (electricity) flows, if a big potential difference exists then a big current flows, even momentarily this does damage like above, heck this is what spot welding does (and how it works). Where is the potential difference? Well if your battery is (say) 46V (very discharged down from its normal 52V) then if the charger is off its got a potential of 0V so there is a 46V potential difference to equalise.

This pitting will cause premature death of your charging connection plug (which in my case the terminals are gold plated for better contact, so I'm destroying that for a starter).

Why has it happened to me? Well some times I forget that I've unplugged the charger (or I've moved it between places and haven't turned it on at the wall).

How do avoid this damage?


Many batteries on scooters are permanently simply hard wired to the charging port, and much of the smarts of charging is in the Battery Management System (BMS). If you attempt to plug the charger in when its turned off the charger plug wull be at zero volts, so there will be a potential (probably 47V) difference between the plug (and the powered down charger circuit it leads to) and to the battery terminal. This will cause exactly the damage you see above as the electons briefly surge across to equalize the voltage.

By simply turning on your charger first you'll have it sitting at about 54~55V and even if your battery is quite run down (45V) then at most you'll have a 10V potential difference and thus very little current flow.
Alternatively if you didn't turn your charger on first then you'll have 0V at the charger end and 45V at the battery and you'll hear the characteristic "TICK" of a spark jumping while it equalizes the potential (electrical pressure) difference.

Lastly don't "take my word for this", go get a volt meter (and if you have an electric scooter you should already have one, they cost like $10) and measure the voltage across the terminals (absolutely  take care to NOT short them out, one probe must only touch one terminal). Measure your battery, and measure your charger. Polarity does not matter if you have a digital multimeter.

HTH


Mercane hills and slopes (speeds, angles and numbers)

Being who I am, I thought that I needed to make some quick calculations and then go see how close these calculations are against reality. So I went out and measured a few of the roads and found the following:

  • the really steep bit at the top of my street (observed in all my videos) is about 10° (so no wonder I need to kick there).
  • the steep hill I used on downhill trials was 4° at the first section and then changes to 5° where I started my "rolling start" video.

Using this calculator (and parameters) I obtained this estimate of what I'd anticipate to be the terminal velocity going down a hill of 5°

Here are the calculations for the scooter:



which suggests that I'd more or less hit a peak speed of 16km/h without power, although as you can see the red curve of "power input" doesn't need to be much (nor the slope change) to go into higher speeds. The bicycle is much faster (with its better rolling resistance):



getting to 33km/h without assistance.

So what do I actually get? Well first I thought I'd do what's more 'natural' on a powered scooter and that's just to power down it after turning the corner, which is what I did here.



I got 28km/h on this run, with a headwind which I didn't factor into the calculations. Recalling that the scooter is speed limited to 24km/h I will assume that the motor provides no additional power then I'd expect that the maximum speed at the bottom of the hill to be whatever gravity VS resistance deterimed was my terminal speed.


You'll see that I got to 30km/h (at about the same place) on this downhill run, which isn't really that different. But because I left braking a bit later I could see that the GPS started showing 32km/h. I would wonder if this is because the sampling rate of the GPS speedo is just catching up or if its also that extra bit of hill I ran it down.

Either way this shows a good congruence between that calculator and actual observations in the wild.

Discussion

Its worth noting that in the manual it suggests that you begin applying brake early on a steep hill. This is what bicycle riders would call a coaster brake, where by braking early you simply don't build up a dangerous speed on long downhills (dangerous meaning that if you had to do something unexpected like avoid or stop you could not).

The Mercane essentially has coaster brakes by the internal resistance of that rear hub motor when its not powered.

It may not look like much but in combination with that disc brake and also leaning weight over the rear wheel its an effective system for the speeds the bike was built for.

I'm still tempted by the dual motor version, but in what I do and where I go with this I'm still not sure that its worth the extra money. Certainly not on the commute to work from where I live, nor on most of the journeys I undertake around here. Its just that the steepest parts of town are over to my mates place. However aside from my driveway (also 9° and super bumpy) I can avoid that long steep uphill I've been working with and I can kick a few times for that 9° slope right at the end of my street (or get off and walk it if I'm really that lazy).

So all in all the Mercane Wide Wheel is proving an excellent choice for my needs and 90% of my wants, and as I observe in one of the video's, if I want more speed or power or hill climbing can just use a faster tool (like my motorbike).

HTH

Saturday, 6 July 2019

Mercane Single motor on hills (with a bicycle beside for comparison)

'Morning

well I've done my street and this block before, but this time I've got some additional information to do with that last post (here).

First is this plot of the same "round the block" I did at the last part of that post where after the longer ride I went up about the steepest hills in my area. this is the plot from GPS showing speed and elevation over time. What's interesting is that the fastest and slowest speeds (aside from when I was just looking around at the top) are on the same actual place, that last "pinch" of the hill where my street joins the other one and the slope changes:


You can see also that after I crest that hill (shown pretty clearly on the GPS elevation) that my speed goes up (of course).

Now to "get real" here for a moment (aside from the "I want more speed" emotions), I think the following video I made on that exact route (but not at that exact time) makes clear that the single wheel is sufficient for hills when you see it with my friend on his bicycle.

Now I'm really sorry, but the wind noise is terrible and I discovered that I am probably hyper-attentive to looking around (think squirrel) and so that makes for a bad video. So with that apology out of the way:


So while that's hard to watch with all the movement and noise (sorry, hopefully my video skills will improve) it shows some important points:

  • the hill at the last bit of my street is steep, even my mate had to work a bit harder.
  • I kicked a bit, but really not much and its not like that's going to work up a sweat.
  • at 1:30 I started pulling away, and by 1:45 I left my friend cycling behind and got to the top at 2:45 ... he arrived 3:19, which is a 34 second lead up a hill. Because it was blasted by the wind I was remarking that "people say "but will it go up hills?" ... and I recon the answer is well enough and this is only the single motor version, not the dual motor version"
  • rolling resistance is a big issue on all scooters, and I'm quite sure that having two motors makes some sort of impact on that.
(as a PS)
I went back this morning and measured that hill and I got a slope (according to the GPS) of 4° but according to my tapemeasure and spirit levels 5°
Here is the GPS plot of my trip (this morning) and I've highlighted the speeds down and up.


you can note a gradual increase in speed on the way down (as it did get a wee bit steeper) and interestingly a gradual increase in speed on the way up (because in reverse it got a wee bit less steep).

Discussion

So while a dual motor would probably scale that hill better I suspect that it will reduce the max speed down the hills because it will give more rolling resistance and (due to speed) the motors will not be getting powered (not least) because of the speed cutout (and maybe because they'll have reached their maximum effective RPM too.

Now in the USA where the price difference between the single and the dual is about $100 its not so much of a decision, but in Australia where its more like $500 difference (or nearly 50% more) it is.

My view on this is that for my weight the Single Motor is sufficient and the $500 better off in my pocket, were I 100kg the answer would be different.

Additionally if one finds that one needs more speed, perhaps you would be much better / safer / well served by an eBike or (shock) an actual motor scooter, like a Honda Dio which I can buy in excellent condition used for $1500 (and that will do 90km/h all day long has bigger wheels and recharges in minutes with liquid energy at the servo).

HTH

Thursday, 4 July 2019

Mercane Wide Wheel: speed trials

So, its a quiet night with no wind and one of my backstreets here is as smooth as it gets, tyres even run almost silent. So I thought I'd do some short speed trials:

  1. "ECO Mode"
  2. "Power Mode"
  3. and the disable speed limiter in "Power Mode"
My scoot is the Single Motor (500W) variant with an 8.8Ah (422Wh) battery pack.

No point in saying more than that

1. Eco



2. Power



3. limiter disabled (Power Mode)


Observations & Opinion

These are short runs, but I could see that the voltage was buckling in (falling) observably on the unlimited run. So basically I wouldn't like to see this run for long on a 4 bundle parallel pack of cells as you'd likely run it into harmful territory quickly.

Why? Well I've been playing with a bicycle energy requirements calculator and found that if I calculate the rolling resistance of the wheels (and sadly for scooters, smaller diameter is a bad thing because its a scalar in the equation : half the diameter = twice the resistance) and plug that in I get remarkably close to what I experienced last night (parameters).

Looking at case #1

We see that I need under 500W (its a single 500W motor model) to maintain that speed (436W actually, sorry I cropped that badly). This is well within the limits of the system.

When I used Power Mode I got this data:


meaning that its using about the full 500W (lets allow a little margin here and also observe that my battery was showing 52V when I started).

Now onto the "unlimited" we see an interesting picture emerge


... and the motors "peak" power is given as 800W. Meaning that if you use it in unlocked for long you'll break something soon enough. This supports my concerns when I've experimented with it and seen the voltage start dropping very fast. I guess it would be race as to which failed first, battery or motor.

As I've already established it works quite acceptably with the Cruise Control, thus I sort of like using it if I know I may need a "dash of speed up my sleeve" but can reliably set the speed lower and not punish the batteries (and maybe motor?) using the thumb trigger. However the scooter resets the "over-ride" made to "unlock" the "full power", which looking at this is quite sensible.

This supports my view that if you think you need more power, get the model with more power in the first place. In this case (Mercane) that would be the dual motor which would give you 1000 watts. Which if I plug in a "big guy" number like 100kg and the extra weight of the scooter with bigger battery and extra motor I get this:


So like I've been saying to people, if your bigger (and or you want to hustle up more hills) then the dual motor version is the one to shoot for, but for me the single is entirely adequate.

Remember, they're both speed limited (in Australia its 24km/h), so that above result will see you going up hills better too.

Perhaps when I upgrade the battery pack from 8.8Ah (not planned any time soon, but probably inevitable knowing me) to have more Ah capacity I'll be more enthusiastic about using it on Unrestricted Power Mode.

Tuesday, 2 July 2019

Mercane goes shopping

If you haven't guessed I like this scoot ;-)

So, tonight I have put an app on my phone that does a good job of logging trips. So I took the scoot up to the "further" shops (to go to Bunnings and then get a bottle of red for dinner) to do a documented test run. I sort of scoped the trip on Google Street view first (so I wouldn't have to look at maps on the way) and only got lost once on the way there.



So, this is the data produced by the logger



After wandering around Bunnings (for non Australians this is a huge hardware franchise with equally huge warehouses) talking on my phone I went to the "bottle-o" for a bottle of Shiraz which was further up the hill (thus the different starting altitude).



Now the better peak speed on the way home was down one of the hills which was a significant slow down on the way out.

I left with 50V on the dial and got back with 46V on the dial (which is 3.53V or there about per cell), so not "punishingly low" and not from "full" either, with a few long moderate hills.

46 seems a good point to whack it back on the charger because (to recap) with a 13 cell pack that's 3.53V per cell, so somewhere between 30% and 20% total discharge:



I'm pretty pleased with this result (and it was a shitload of fun on the way home too).

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