GoPro Hero 3+ mic wind muff

Wind noise on a GoPro is a PITA and I've had quite an amount of success with a few small mods on mine to cut down noise.

This weekend I decided to try to improve it both in function and aesthetic (because it was looking rather Frankenstein earlier). My solution is to put a tiny bit of foam over the small mic hole and in conjunction with that some bluetac to seal the places where the wind can get in under the black frame. Here's what it looks like now

The astute will notice I broke the frame on my last insert back in ... sigh

You can see that the foam is held down with a small amount of double sided tape, and a small bulge under the frame is created by the blue tac;  visible at the front (the previous solution was putting it all the way along the front).

Basically you make a small "sausage" with the blue-tac (like a 1mm diameter) and form a circle which will be larger than the frame hole (and of course not block the mic holes) and then put it into the frame and sandwich it down.

You can see there is a little gap in the top of the frame, but that'll subside over time as it squeezes down. (and you can see the crack of the broken frame ... sigh)

Oh, the bubble spirit level is pretty handy too ... that was like $5 for 10 of them on ebay. I'm still finding uses for them ...

So the materials list is:

• a few mm of double sided tape (had that in the tool cupboard beside the Duct and Gaffa tape anyway, so no money spent)
• some sponge from kitchen sponges (again, had that on hand under the kitchen sink, again n money spent)
• some blue-tac (in the desk drawer another $Zero spend)
• some time (nobody pays me on the weekends)

The pudding

So the proof of the pudding is in the ... well listening

not bad and not expensive.

Lastly, thanks to Jacob for this GoPro ... you're a legend!

And, I just discovered this is post #1000

#milestone

steering trail

Steering geometry is a pretty well studied area, and hapilly few motorcycle or bicycle riders need to give much thought to it (although the advanced riders certainly do) because ... well because the best riders already have, and have worked closely with the engineers and makers to make sure that everything is done right. Its pretty well understood these days (like the last 50 years).

Sadly most of the the eScooter community is entirely ignorant of it and the internet fora are of course rife with fools and idiots who know a few buzz words (or don't) and dismiss this idea as etheric.

This results in the perpetuation of unsafe scooters on the market.

In short, trail is the distance the contact patch is behind the steering axis (just as in a castor wheel on a shopping trolley or office chair) on a Scooter it looks like this:

The angle down is called by some the "rake", this angle helps but trail is the main factor in stability (like a castor wheel).

Now this is a common amount of rake and trail on a modern MTB

yet on many modern and fast scooters the amount of trail is dangerously small, such as this Zero which is almost nil:

In contrast both of my scooters above (the Widewheel and MX60) have quite well designed amounts of trail

... meaning that I can briefly let go of the handle bar to (for instance) hand signal a turn, for instance even at high speeds the steering is quite stable:

While many scooters (such as the zero above) are so inherently unstable people consider "steering dampers" for them.

My Giant MTB for instance has the following spec published on the Giant Website:

although what is called rake here is probably offset, and another meaning of rake is the angle that the forks are raked at (which influences flutter of the wheel or better known as wobbles).

Meanwhile eScooter riders wet themselves instead on top speeds and the "advanced" riders know fancy terms like "steering damper" (which essentially means bolt on fix for shit geometry). So as I said at the start, well understood and a published spec in the bicycle world and in the motorcycle world too ... just not in the advertising mush or reviews (don't start me on how miserable and technically ignorant most reviewers usually are).

For the interested I'll leave you with some good articles to read up on this:

The obvious one is this https://en.wikipedia.org/wiki/Caster which soon leads to an issue of flutter:

One major disadvantage of casters is flutter. A common example of caster flutter is on a supermarket shopping cart, when one caster rapidly swings side-to-side. This oscillation, which is also known as shimmy, occurs naturally at certain speeds, and is similar to speed wobble that occurs in other wheeled vehicles. The speed at which caster flutter occurs is based on the weight borne by the caster and the distance between the wheel axle and steering axis. This distance is known as trailing distance, and increasing this distance can eliminate flutter at moderate speeds. Generally, flutter occurs at high speeds.

which naturally leads into: https://en.wikipedia.org/wiki/Caster_angle#Two-wheeled_vehicles

and finally: https://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics

If you have not yet chosen a scooter I hope this article has opened your eyes to an important aspect of scooter safety.

Happy and Safe scooting

what's the fastest speed the Widewheel can do?

Some people just love to believe their scooter is fast (its just King Wang if you ask me), but what's worse is that on a scooter with no speedo people claim all sorts of things implicitly in making statements like "for a scooter which can do 40mph" which is of  course nothing more than a resellers claim to suck the kiddies in.

The reality that I've found is that 43kmh in ludicrous mode is the maximum, and that's even giving it grace on a gentle downhill. So today I thought I'd settle it with actually making a point of having a fully charged battery, driving to the top of the hill and from "fresh off the charger" let it run down the hill with the throttle locked on in ludicrous mode.

So you can see that on a road where its pretty consistently steep it got up to 46 kmh.

For Shits-n-Giggles I repeated it more or less with just gravity (and a little bit of help to get started)

So basically this clarifies that in no way is more than 44kmh possible on a flat (even with a little tail wind), which for the American readers that's a smidge over 27 miles per hour. Nothing like 40mph.

Now I mentioned during the video that every electric motor will have a maximum speed, part of that is determined by voltage. Because as the motor spins faster it provides more back EMF acting against the battery. Eventually you'll reach a point where they're in balance, as you saw in the voltage meter where it was just sitting on 54.0V

Lastly here is the video  made during this GPS gathering:

Conclusion

This should not come as any surprise, because even if you jump out of a plane there is a top speed you'll reach. To get more speed will require more power.

Anyway, this is pretty rigours and avoids any of the heavy duty wanking that juveniles are prone to. As I've said before, this is a great scoot and its a lot of fun, but please, keep it real. Leave the Kool-Aid back on the shelf.

Just the Facts Ma'am.

Distancing

Always nice when your transportation provides a decent seat

Nice to get out of the house and watch the sun go down

MX60 tyres (or why I won't be selling the WideWheel)

The MX60 is proving a very interesting experiment for me. Yesterday marked a month of ownership. Over easter I've taken the opportunity to put a few more miles on my MX60, making it to 500km in this time. So I've now got some experience with it to make some sort of evaluation.

One of the things I "knew" before even buying my first scooter was "I wanted to avoid pneumatic tyres". So within a month of ownership I've already had my first example of why this was. I went to go for a ride on Saturday morning and found the tyres were very low in pressure.

Already (I thought) - Fuck Me!

A quick inspection confirmed I could ride it to the local servo (1.5km) and there I found that the pressure was down to 10PSI in the back and 15 in the front (they'd been 30 each the morning before).

Got to the servo and with the hose attached (found the pressures) but when I put the first squirt of air into the valve dust blew out from all around the rim where the tyre bead had seated. An obvious indicator of what the cause was. Dust gets in around the bead.

So what happens is that as the tyre flexes (bumps right) all that dust (thrown up by the front wheel) bathes the rear wheel in a perpetual dust cloud. Then the flexing of the tyre allows dust to get snuggled into the crack between the tyre and the rim. Slowly but surely this pushes down into the crack like a wedge and allows a tiny amount more dust in behind it (rinse and repeat with every tyre revolution).

Note this segment from the above pano (which I took out on the road that day).

See how much dustier the back is from the front?


So I nipped into town on the motorcycle (doing you know, like normal highways speeds such as 100kmh, so its hard to get wet about 40kmh that scooters do) where I got some slime to put into the tyres.

I pulled out the valve stems (there's a tool included in the cap of the bottle) and put in what I determined was about the right amount (scaling my wheel for volume on their charts) added about 4oz to each wheel. I did this with the scooter lying on its side to maximise the chances of it getting "up" into the bead area. It takes a few goes of spinning the wheels to make sure it spreads around and then I flipped it over onto the other side.

Yesterday I did about 80km with about 1/3 of that on dirt farm roads (like above) and its still doing ok.

So yeah, while the better suspension and pneumatic tyres allows me to take this scooter places I couldn't take the Widewheel it also comes at a greater cost. I was fortunate to be observant enough to notice this before going out on a ride (and also living near a servo) so that I could essentially "nip this in the bud". It could however have been a lot worse including a deflation and damage to the rim (and also me). Yet  in the (almost) year that I've owned the Widewheel I've had (of course) no such problems.

In contrast to this, in the time that I've had the Widewheel:

• I haven't had to do a bloody thing to the tyres, no perssure checks, nothing.
• I've hit some pretty good obstacles on the Widewheel, ones which would have caused a flat  on a tubed tyre. So I've not had to do any work on that area, and having changed tubes and tyres on bicycles I can assure you that I'm not looking forward to doing that on a tiny 10" rim (because that makes it so much harder).
• I've pulled nails out of my Widewheel rear wheel and just kept going ... a tubeless or tubed tyre would be toast, probably even with slime.

That single aspect (the foam cored tyres and not having pneumatic tyres) has probably saved me many hours (not including the walk home or the taxi ride to work) right there.

When you add to this that both my Widewheels are light enough that you can easily put it in the car, and indeed have been used extensively to chuck into the car and go somewhere to be used as "last mile" (or last 10 miles) it makes the Widewheel not only a fun scooter to ride, but bloody practical. Indeed the uses its had are (but not limited to):

• commuting to and from work from my accomodation in the city
• being able to park outside controlled parking space and get to and from places without paying for parking
• stuff into the car to take it to get something done at the workshop (where I can then scoot back home or to work while that's being done), then scoot back again.
• just nip up the shops to get something
• visit friends that are just a bit far to walk to, and I'm probably too lazy to use my bicycle

Most of these things can't be done by the MX60 (because its so bloody big and heavy) and indeed I've already needed other transport to get stuff to fix the tyres MX60.

So while I enjoy it, and while its interesting its not as much sheer fun to ride as the Widewheel, nor is it as fast and practical transport as my motorcycle, nor has it replaced me using the Widewheel for quick trips in town. Worse its not fun at all until you're pushing it at speeds which are still laughably slow by motorcycle standards and far riskier than a motorcycle if you have a fall; whyich is more likely on the scooter.

Meaning that its really mainly a play thing or something someone who's too lazy to get a motorcycle licence (or perhaps any drivers licence). If you lived in the city in an apartment (a good case situation for owning one instead of a motorcycle or car) then its still probably too big for daily use and too big to wander into the supermaket with (and parking it at shops? hello?) Putting it in the uncomfortable category of being a wankers toy.

I'm comfortable with that, but then I live my life being honest with myself.

I have not yet bitched about the electronic fault that occurred with the speedo ... perhaps another day.

While its a holiday I'll take it out for a ride soon.

PS: it was flat again this morning (of fucking course it was) and so I went down to the local car workshop (I get my 4WD serviced there) and used their compressor and work space to:

1. pull out the valve stem to let the air out
2. push the tyre off the bead (back down into the wheel)
3. generously paste slime around the bead on both sides of the wheel, where it will seat
4. bring the tyre up to 40 PSI to make sure it seated on the rim nice and straight
5. put the valve back in the stem
6. reinflate
7. spin up the tyre
8. clean up the crap flung everywhere

holding pressure well at the moment ... lets see what tomorrow brings

PS-2: ... pressure down 10PSI overnight

PS-3: seems to be fixed. My view is that it went like this:

1. deflation #1 was caused by dust between rim and tyre
2. subsequent to addition of slim seem to have been down to a faulty valve (perhaps it got slime on it? Because:
3. replaced valve with new valve and no deflations since

FMD

range testing got me thinking

While I was waiting for the Widewheel to charge (and since  the MX60 had just charged) I thought why not take it around the same trip I was thinking of taking the Widewheel (while musing along in that video), but the other way round.

I reasoned that if the Widewheel could do that trip at 25kmh that the MX60 could do it too at about the same speed.

So off I went on this trip:

which yielded this data:

and while average speed movings aren't ball tearingly faster than the Widwheel, the spike of the steep down hill is worth a closer look.

So, yep, that was fun!

Scoot handled it just fine.

While on the trip I stopped for a few pictures.

and

when I got home I checked the ODO and found that compared to the  GPS there is still some discrepancy:

so it thinks I did 25.7 and the GPS thinks I did 27.8 ... if I could be fucked I'd probably tune that in more.

But who could be fucked making the ODO show you've done more km? #hurtsResaleValue

Lastly the energy consumption on this trip was 781Wh which for 27.8km is 2.8kWh/100km,which is a little better than I've had on other occasions but then  this time I didn't speed ;-)

Happy Scooting

Mercane Dualie Range Testing

A lot is written by people on forums about how charging up to 100%  is somehow harming your battery. I've got posts on that subject recently here. Basically my answer has always been simply: no.

So since I've had my 1000W Dual Motor Widewheel I've basically always charged it to 100%, and usually discharged it to between 50% and occasionally fairly deeply before recharging it. I'm a big fan of evidence and if this fluff idea held any real world water one would expect to actually see such losses.

To actually answer this question I thought I'd take the scooter out for a run to see how it went. This is that run GPS data:

Now as it happens you can add another 1.5km onto that because I went over to visit a mate this morning on it (up a hill most of the way), meaning at least 25km traveled,  and when I got back the Voltage was still over 45V under load and settled to 47V as soon as I stopped and unloaded the battery. This indicates it had a bit more up its sleeve.

Charging has yielded the "consumption" of 387Wh (based on the 150A meter measuring input to saturation) which means that 25km consuming 387Wh = 16.4Wh/km or 1.5kWh per 100km (or pretty much what I observed here).

Now this is under "full power mode" and with (as you see) some hill climbing too (so not just perfectly smooth flat pavement) and if you watch the video of segments of the ride you'll see with a head wind much of the way as well.

When you consider that since I've had it its been recharged between 2 and 3 times per week since I've owned it (so for about 10 months) and returned at least this result on this , this, and this occasion then I think that IFF there is any loss its only found on bench test equipment.

This to me suggests to stop worrying about pointless shit and just ride your scooter.

My observations are that spending that time on actually servicing and inspecting the scooter will make a shit ton more use in extending the life of your scooter.

I look forward in any comments to a rigorous and detailed real world demonstration of evidence to the contrary.

So The King is Dead ... long live The King

cell obsessions

One of the thing I often find is that: the less one knows, the more everything is clear (and the "name" brands are simply better). This seems to carry through with scooters where people come to the topic usually knowing absolutely nothing about electronics (worse, perhaps some odd incorrect ideas) and then start to learn a few things and then tuck that away as "known lore" ... often its not based on science or engineering. The cells in our batteries is one such topic where debate and passion often rages about "LG cells" (rarely Samsung or Panasonic) being the pinnacle.

I do try to say that whatever the retailers claim (and you believe used car salesmen too?) as its sealed in a shrinkwrapped pack you just won't fucking know unless you strip it back (probably voiding warranty) and look for yourself. I'd say almost none of the vocal Wangers ever do this.


While I was doing my various stages of repairing my 500W single motor battery pack I posted (in here) that I had found what I think was the cells used in my pack.

From this blog post I wrote:

this makes me wonder if this is the newer chemistry with Nickel in it?

INR - NMC - Lithium manganese nickel

The reigning champ of the 18650 vaping world. This chemistry adds nickel to the IMR chemistry above, making it a "hybrid" chemistry. It combines the safety and low resistance of manganese and the high energy of nickel.

The resulting battery chemistry gives you a reasonably high capacity and a high discharge current. Importantly for vapers, the chemistry is very stable, meaning that you don't need expensive built-in protective circuits. 

There is extensive innovation within this chemistry as well. Sony, Samsung, and LG are all developing next-gen INR batteries with different ratios of manganese, nickel, and cobalt. 

which when I examine this in context of the earlier mentioned blog post it becomes very informative.

Also, a little web  searching revealed this test on what appears to be the same batteries. I think its reasonable to believe that they are more or less the same as the cells that are in my pack. His conclusion was:
Conclusion
The cells looks fairly good, they are obvious not for 30A, but 20A looks fine.

So that site (lygte-info.dk) has that excellent tool for making comparisons. Since I can't share such a link here's a screen grab of the Parkside battery beside the ("Famous") LG branded one.

Now I actually used that image for a different discussion (I'm into reuse) and the red line from 3.5V shows the point where its performing under load (riding along, probably up a mild hill) a little while into your ride. Now I notice many people seem to have forgotten how to read graphs (so pardon me spoon feeding here) but the LG battery falls to the same voltage as the Parkside does nearly half an amp hour sooner.

Now that's per cell, and recall that our batteries are composed of many cells in bundles (please see this post for details) and strings, however what matters here is the P bundles for the Amps. We often have 4 (or even more) cells in this bundle. So for each cell to be needing 3A with 4 cells that would mean you'd be pulling 12A out of the pack (3 x 4 = 12 right?) which is entirely possible with (say) a 500W single motor scooter (usually 1000W motors have bigger P in their battery config).

So in the above the Parkside delivers better Volts well into the ride with less of a slow down (remember V = speed) until just before failure.

Pretty good isn't it. Even better my observations (and calculations) have shown that my own yield from my Mercane battery pack is pretty consistent with the better red curve of the Parkside. Further the only other thing is how many cycles you may get, and I can say that after nearly a year of frequent riding I find no observable (based on distance, speeds and GPS data) degradation in my battery pack.

Case in point, I was riding it around yesterday (well and the day before) and had done over 20km (some of that on ludicrous mode and pushing full speed on down hills) and observed on the way home that the voltage was buckling down to about 44.5V suggesting to me that it was time to recharge. Now even though the voltage popped back up to 47.x when stopped, don't be fooled, that's not how batteries are measured for discharge. So I put my 150A inline and recharged. It took 8.61Ah to charge. Looking at the curve from the site at lytge-info and applying my numbers we see this:

• approximate discharge based on observed voltage was 10.5Ah
• my recharge was actually 8.6Ah
• given the above cell is 2000mAh not the 2200mAh my cells are this more or less accounts for the difference and 
• given that I was discharging at an unknown rate (probably higher than 6A understanding the Watts required for the speeds) it works out about right

Not bad for a pack that has had at least 100 cycles of 100% recharge (if like that even matters compared to other factors)

So play with that comparitor tool and check out some batteries, go price them and then decide if what you have is a sufficient cost benefit for you. After all some people want to balance how much they spend... looking at the discharge curves, frankly I'm glad I don't have LG cells and instead have money in my pocket. A year later and evidence shows there's nothing wrong with what was in the scooter.

social distancing and getting exersize outside

Went out on the scoot today, wanted to clear my head after a day inside.

The light was so nice

Just cruising and listening to the birds

Stopped to take an occasional photo too

Stay safe out there people :-)

MX60 - first inspection and tweak

Although when I got it I naturally went over all the bolts (and found the rear-suspension ones needing a tweak), I thought this rainy weekend provided a good opportunity for a pull down.

So, I put this video together of what I did and some observations about the scoot during it.

I made mention of some points on the suspension which need an occasional eye too.

I started talking about the battery, and later decided I'd do a pull down of that too to see what was inside the battery box and if I could see anything to help me with why it has two connectors. Sadly I'm still a bit mystified.

So with the screws off I could lift the case lid (body aluminium ends plastic) and see what was in there.

I was both surprised and in some ways pleased to see that it contained a regular battery pack of the type that I can easily buy on AliExpress.

although I'm left a little mystified as to the charging arrangements. Essentially there are the following wires going in/out of the pack:

• power wires coming out leading to the XT-90 connector to the motor systems (the thickest ones) 
• two pairs of wires (one pair each from the pair of charging ports)
• one very small pair of wires for the voltage / SoC indicator on the battery

So in essence this does not answer my primary questoin, but at least I know that if I need a new battery it's a simple matter to slide a new one in there and wire it. Nice.

The MX60 then continues to show its well thought out build quality and ease of maintenance ... I mean anyone who's pulled apart (tried to pull apart?) one of the other high power scooters (Zero 10x and clones ...) knows how bloody hard it can be to get at the battery pack (let alone service anything else).

So from an ownership / service perspective the MX-60 is even easier to work on than the Widewheel (well except for its heavy to haul around).

I can say so far its entirely met my expectations

should I fully charge my scooter or not?

This is an often asked question on forums and results in much discussion, many seem obsessed with preserving their battery on their new scoot. Makes sense, I am interested in not harming mine also.

First, the Short answer:

To me the simple answer is: YES you should.

Details

The devil is always in the details right?
First and foremost you should always examine any answer and check it for veracity. If nothing else I expect anything I write to be a good jumping point for your further research ... if you have doubts.

Now lets examine the proposition here because it relies on people assuming that the makers are stupid (and some unknown twit on the internet is a genius) and then having just enough knowledge to be dangerous. Perhaps there is also some problems here in that some of these self assessed geniuses may be best described in this blog post, but I digress.

Battery and Cell are used interchangably in common language, yet the dictionary is clear:

There in lies an important difference and one which is probably the root of many misunderstandings.

The Cell

The problem (and why people say you shouldn't charge your batteries fully) is based in this often cited Battery University article where discussion centers on cells (that's individual cells and not even restricted to 18650 cells that our scooter packs are currently composed of) were stress tested and a finding was published.  It starts by showing the results of high discharge rates of a particular chemistry (of which there are a few that continue to evolve).

Now, lets look at what they wrote about this:

Figure 1 illustrates the capacity drop of 11 Li-polymer batteries that have been cycled at a Cadex laboratory. The 1,500mAh pouch cells for mobile phones were first charged at a current of 1,500mA (1C) to 4.20V/cell and then allowed to saturate to 0.05C (75mA) as part of the full charge saturation. The batteries were then discharged at 1,500mA to 3.0V/cell, and the cycle was repeated. The expected capacity loss of Li-ion batteries was uniform over the delivered 250 cycles and the batteries performed as expected.

The graph Fig 1 is as below

To get more than 4v out of a cell we arrange cells in strings (called series) to go to higher voltages. The voltage is simply just the addition of how many cells you make in the series. Like this

Now the reality of our battery packs is that they are not strings of single cells because each cell only has about 2 ~ 3 Ah, while we'd often like more like more than ten. So they are in fact composed of strings of bundles of cells:

1. parallel bundles of cells to increase the available Ah (typically 3, 4 and 6 2,200mAh cells giving 6.6, 8.8 and 13.2Ah)
2. these parallel bundles are arranged in a string (seen above called Series) to increase the available Voltage, such strings are often 10, 13 and 16 (36V, 48V and 60V) because the "nominal" volatage of a cell is usually given at around 3.7

This is normally given in an abbreviated form like 10S3P or 13S6P or something like that depending on your specific battery (I have 3 scooters with 3 different battery configurations).

Now, to replicate their outcome you'd have to discharge your battery solidly with no break, no let off at the same rate. Meaning if you have a 4P configuration. So you'll have to ride your scooter so that the motor draws 6.6, 8.8 or 13.2Amps unrelentingly till its dead.

I'd argue that's not only not what happens, but probably possible without something else failing.

Next that article goes on to discuss another aspect, depth of discharge and fullness of recharge. They state the following:

In terms of longevity, the optimal charge voltage is 3.92V/cell. Battery experts believe that this threshold eliminates all voltage-related stresses ... Most Li-ions charge to 4.20V/cell, and every reduction in peak charge voltage of 0.10V/cell is said to double the cycle life. For example, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only 4.10V/cell, the life can be prolonged to 600–1,000 cycles; 

Seems compelling,  however then it says:

On the negative side, a lower peak charge voltage reduces the capacity the battery stores. 

... so you want to have high capacity cells (to make high capacity batteries) but then not actually have high capacity batteries anymore so that they may last longer? This becomes more clear when you look at table 4 and its notes:

and pay attention not just to pick the bigger cycle count, but to read the details, like the "Note:" in the middle over there and to Experiment: making reference to to vehicle (meaning cars) at the bottom, and in among all that TLDR writing.

So to get longer cycle life (defined by what?) you need to reduce the capacity as well as the power of  the battery (recalling power = Volts x Amps).

Personally I love the extra power that my scooter has when 100% charged.

I see many people asking about how to get more power from their scooter, so its pretty clear that the answer can't come from under charging.

Next in reading the details you'll find this:

Discrepancies exist between Table 2 and Figure 6 on cycle count. No clear explanations are available other than assuming differences in battery quality and test methods. Variances between low-cost consumer and durable industrial grades may also play a role. Capacity retention will decline more rapidly at elevated temperatures than at 20ºC.

 ... so maybe its not as cut and dried as these studies suggest and then (importantly) will you ever be riding it in summer because temperature plays a bigger margin?

I encourage you to not just skim through that article cherry picking but to really dig in deep if you want the actual answers. If you do you're going to find that this is a very complex subject and has a lot of parameters such as but not limited to:

• temperatures
• chemistries
• cycles of depth 
• starting charge
• duration a cell is held at a charge
• discharge intensity

Are you yet getting the picture that everything is a trade off?

Moving to a battery not just the cell

Now lets consider the actual practical issues in charging our batteries (an array of parallel cells in bundles in a string of bundles) and note that it would be pretty much impossible to charge  all these without a Battery  Management System (BMS) which then distributes the power to each of these. This is the BMS in my battery pack.

Now this is a composite of two images, seen from top and side. The BMS is connected to each bundle so that it can be charged individually. Without this such a system would pretty soon go out of balance and be useless.

Balance?

Yes, each set of cells needs to be not only the exact same chemistry and rating but needs to be at the same voltage when charging is completed, if we just wired these all up and applied 54V across the pack then maybe (maybe) in the beginning it would be able to be completely charged in a uniform way with no cell being forced over the 4.2V and coming to harm (like exploding). This is why its simplistic to just think of that black box that plugs into the scooter as the charger. Its actually not the charger and the BMS is the charger. It makes sure that when any bundle reaches 4.2V its ceases charging, to protect it (and you).

However the reality of this is that because nothing is identical  (and less so with age) not all cell bundles come up at the same time. Were the BMS to just shut down when the first bundle reached 4.2V then pretty quickly the other bundles would fall behind and not have the same capacity. This will result in the pack not being able to deliver its rated output. (disappointing)

Why? Well this is because one of the other functions of the BMS is to protect the cells, you see not only is charging too high a problem but under voltage from "over discharging" is dangerous and can harm a cell. The BMS does this by sensing all the cell bundles Voltage and then shutting down the power output (like an off switch) when any one of the cells falls below its low voltage threshold (often 3V).

Lets examine my pack (which I pulled apart because the BMS was not doing its job, but lets get back to that point soon), when I pulled it down I got the following voltages from each bundle:

You can see that bundles 2, 5 and 11 are significantly lower than the others and bundles 1, 3,4 and 10 are higher.

So this pack was unbalanced and resulting in the following symptoms

• when BMS shut off charging, scooter display showed 54.4V but unplugging it that fell instantly to 52V (some would cheer saying this was good as it wasn't charging to 100% (52 divided by 13 is 4V which would seem good to the less well informed). lets get to why in a moment.
• BMS would trigger a pack shutdown before full safe discharge range was reached because the lower cell (bundle 5) would be exhausted and fall below the critical voltage before the other cell bundles. The BMS is then preventing the cells in that bundle from being harmed by excessive discharge.

So why didn't the BMS bring all bundles up to the same Voltage? Well that requires an understanding of how a BMS works, which is a lengthy blog post in itself, but just keep in mind the following things:

• the BMS can be Active or Passive. A passive BMS can only bleed power from adjacent cells  (so like bundle 2 could get power from bundle 1 or 3 depending which was on its negative side) while the Active type can continue charging individual bundles longer. However all BMS have limits (and trade offs), read this article if you're keen to learn more.
• many BMS have a limit on the voltage difference which they can cope with for some thats 0.2V ... meaning that if a bundle is greater than 0.2V different to the higher ones then its left behind.

My original factory fitted BMS was a Passive type and I changed it for an Active type, happily the pack quickly recovered giving 54.5V soon (in recharge count) after fitting the new BMS. To nudge it in the right direction however I balance charged it manually first.

which of course took some hours of time ... because I had to recharge each of the 13 bundles.

Why did my pack become unbalanced? Well I'd say there are a number of candidates:

1. I think my pack behaved like this (dropping to 52V instantly after unplugging) from when I got it. This may have been caused by the dealer I bought it from allowing some people to test ride it (and the tyres showed that to be the case) without fully charging the battery to 100% out of the box. This is a bad thing and should not be done no matter how much of  a worry-wart-fusspot you are. These things need to be done to ENSURE it starts out properly fully balanced on the first "grooming" of the chemistry.
2. I on a number of occasions was impatient to get going and gave the battery a charge to nearly full and then went on longer rides (like 12 or so km) to go shopping
3. The BMS may have been faulty or a poor design type of passive BMS

Either way it happened and its fixed.

Conclusion

As you can see there's more to the entire question than the simple "don't fully charge it" as there are many trade offs. Most of the literature focuses on where the "real money" is and that's cars. Cars which like Tesla have over seven thousand (7,000) cells inside, not 30 or 72 or even 128. Given the cost of a 18650 cell at about US$3 that means there more than $21,000 in just 18650 cells in a Tesla and you can buy an entire battery pack for a scooter for about $200.

Ask yourself these questions:

1. are you fussing over nothing?
2. are you suffering from new buyer fussing?
3. might you do more harm to the pack by imbalancing it than potentially preserving the cell life
4. didn't you want more power anyway?
5. didn't you want lighter?
6. in reality how many cycles are you likely to do? Do you run out of charge so often that you need to charge more than 3 times a week?
7. how can you control temperature in a scooter?
8. everything has a life span

and a perspective from a well known battery builder:

Lastly to me the low hanging fruit is exactly as said in this video: fully charge it, preferably timed so that its ready just prior to use. Then get the usages out of it and when its at about 30% remaining, charge it. This will minimise the charges, minimise the time at higher voltage and result in the maximisation of cost, benefit, and enjoyment.

So yes, I almost always fully charge mine when I charge it and so far its done over 1000km and based on final charge voltage and range tests (which are a pretty good indicator of battery status) the scoot will still do the same ranges it did from new.

HTH

Widewheel and MX60 in a side by side (uphill) race

Yesterday afternoon I decided to do a side by side video race of my Widewheel vs my MX60 this is that:

In an totally expected outcome the MX60 won this because it has the top end legs over the Widewheel and I didn't want to unrealistically punish the battery on the Widewheel by flogging it up that hill on unrestricted mode (nobody is going to buy me a new battery right?) and I don't normally ride it in that mode. I do however ride the MX60 as presented.

There's not much else to say here except that that to me the differences in times are significant in a race, but not in travelling to visit my mate who lives there, like what's an extra 15 seconds shorter travel time? The MX60 is more plush but somehow less fun (for me). The Widewheel gives me the feeling that "I'm pushing it" without being at speeds which may see me in the spinal unit were I to fall off.

Out of the box the MX60 needed (and to my mind still needs) some tweaks (many of which were settings, see here) but it still needs some physcial tweaks to be able to have the required room and foot support to ride it properly, not just be like some dope who stands like a statue (like this dope who isn't even using the rear kick nor any sort of posture for riding):

so if you're like him you'll just love the MX60 and its stupid deck design will make you feel its a lot faster than you can cope with. Probably you'll be bending the steering stem within a year ... but hey you can afford to sell it then right?

Widewheel dual commute to work

Normally I throw the 500W Single in my truck to use in the city, but I decided to lend that to a mate as I now have the MX60 (and 3 scooters  at home is ludicrous). For some reason don't have data  this trip on the 500W model, but I recall it wasn't much different to the trip to the shops just across the road which was about 20min (and that trip is a bit longer with some more curves and lights).

So, to refresh, my course is this one:

Method

I decided to do a run with it on unrestricted mode, and to moderate the power using the throttle and cruise control. This is actually difficult (and I don't normally do it) because every little bump makes it hard to hold the throttle steady for the required 7 seconds. However on (even mild) down hills I can just push it down all the way, making engaging cruise control easier, and not worry about the hard hitting power drain because the higher speeds balance out the maximum amps it can suck with higher back EMF.

There are a few smooth patches of cycle path where I was able to cruise on what I know by feel to be above the "restricted max" speed, but looking at the voltage drop (because of load) am able to pick a speed that's not too punishing on the battery.

So the stats for the trip are like this:

and its pretty simple to see where the steep up hills are (and I can notice the reduced time I was going slower and the increased speed on those). The downhills are pretty clear. The trip is mostly a gentle uphill as you can see in the elevation.

Maximum speed for such short durations really isn't significant and if anything I think what matters is that but the average speed (and average speed moving) are pretty good. I only had to stop twice, for roundabouts and intersections.

This is the same run but just keeping the normal restrictions and using Power mode:

The Dual does make this trip a bit shorter as its typically 18 minutes, so I shaved 5 off. Which in the greater scheme of things isn't such a big deal, but it is a bit nicer just to be swishing along that little bit faster. Were there more places with intersections (with lights) I'd probably see even less difference in point to point times.

I have serious doubts about wanting to take my MX60 here because the bloody thing weighs too much to hump in and out of the wagon and in reality would probably only shave another 3 or so minutes off the trip.

So there you go. Again the Widewheel dual motor is shaping up as a nice sweet spot for commuting under 10km each way.