interesting read
i am looking at ultra capacitors as my next upgrade, they are almost at the W/kg of 18650s, but i could still give myself allot more Ah (35-40 i think) the same space as 2 x 26Ah battery
best thing is, potential for full charge way under 1hr (maybe 20mins!)
The factory is just starting to ramp up production in China now, fingers crossed i will have working prototype before the end of summer!
After that i will look at controller to improve acceleration, then next year maybe look to increase speed (depending on legal checks and insurance practicalities)
What's the benefit of capacitors aside from ultra fast charging, where the question rises where can you charge so fast and how often do you really need it?
I would rather have faster acceleration / more range / more top speed than just faster charging.
Rapid charging has 2 benefits, the first is obvious, being able to do a full charge in under 30mins, means i can ride much further in a day
The 2nd is maintaining acceleration, which usually drops off rapidly once the battery starts to deplete and V drops
being able to quickly top up, a 10 min charge back to max, ensures full Voltage is available more frequently
in addition: The rig i am building will offer 69.7V for allot longer than the Lithium is able too, using a DC-DC boost circuit (actually will be a pair of parallel synced-feedback boosters, each able to provide upto 20Amps each and a steady 69.7V)
Total charge will be around 35Ah (exact charge i will have to calculate later, because of the way I am running the caps and DC control, some charge will be lost to inefficiency, although not much - but it doesn't matter, when i can charge so quickly) - using DC boost will also use some of that power, esp as the caps deplete
I should have the first prototype ready before the end of August, i'll do a full build post about it - cost is, of course, higher than buying an official TS battery, but its benefits are worth it, and I believe it will last longer (60,000 charge cycles)
Once i have this working, I can look to increasing the voltage slightly during acceleration, which will require a new controller - I am also hoping to get that additional power from a second set of capacitors, which will be topped up via regen (have not yet crunched the numbers here, my first step is a viable super capacitor battery replacement
@socomods
Do the super or ultracapacitors have a higher possible discharge current if they can charge that fast? That would then also allow for a bit more power from the existing voltage. I had no idea they were even making caps with the energy density to be anything more than used in tandem with a battery. I saw a really cool application of that that would utilize the fast charging and regenerative benefits of caps with the energy density of batteries.
Discharge current can be huge yes, hundreds of Amps
the design i am working with is for 60A charge to full over 30 minutes or 30A over 1 hour
Using them in combination with Lithium is a potentially good solution for improving acceleration - depends what the controller is capable of
Super capacitors with lithium level energy density are of course very expensive, but because of there extremely long life span, it is possible to add additional parallel cells to increase Ah over time - something which is not sensible with Lithium (and will likely lead to fires and explosions)
Important to bare in mind that capacitors have an almost linear discharge, so the voltage drops quickly (linearly) with discharge - where as Lithium does not; so controlling the Voltage and Current into the bike is more critical
there are quite a few fast chargers around cities these days - but in addition, a multi-kW charger that plugs into a domestic mains supply is not to hard to find
PS note on range. The bike should be able to hold 2 super capacitors (plus a smaller acceleration booster), potentially offering 70Ah + 1Ah - but im not that rich at the moment. - i also felt it was safer to not over pack the bike, heat will be generated, I have no idea how much - although these caps will not cause catastrophic explosions like lithium, they are expensive to replace
Thank you Nardcox, I will receive my TC in a week or two and was thinking of doing almost the exact same thing as you -swap out the motor, new controller, build diy battery (funny enough I had the same 29E cells in mind).
Looks like I can learn a lot from your project and not have to reinvent the wheel again! Thank you again, the time and effort that you put into describing and logging everything is highly appreciated (at least by me).
Bob (ook Nederlands maar woonachtig in Spanje)
Thank you Nardcox, I will receive my TC in a week or two and was thinking of doing almost the exact same thing as you -swap out the motor, new controller, build diy battery (funny enough I had the same 29E cells in mind).
Did you get further along with your project?
Where can I buy a new wider rear swing arm that can fit the QS 4KW motor?? Preferably in the EU.
Also I'm getting stuck connecting the controller up to everything, my knowledge is simply put to limited. Anyone who would care to help out? Physical or via camera would be possible. It will be highly appreciated, haven't properly driven the bike for months now.
@nardcox still doing research before I make the great leap of buying a motor and everything else.
My main concern is how big I can make the battery as still will influence the eventual continuous and peak power of the motor. I reckon a 20s30s pack is doable in the current plastic housing of the battery compartment but perhaps I can push for a 20s35p or even 20s40p if I do some modifications.
Regarding the swingarm I have no clue where to get a bigger one but if I remember correctly from your photos, the difference wasn't all that big was it? Perhaps getting the original swingarm modified? Or even have the motor thinned down my a machinist and a lathe.
I'd love to try and help out with the controller and see if you can get the motor spinning. Send me a DM and I'll pass you my phone number.
Yeah, do you research, it's a big 'investment'.
How much power (W) do you want to pull? 20S20P will fit in a single / standard form. I have 2 packs or 10S20P and connected them in series. See my pictures. https://photos.app.goo.gl/rWyHYPyg7BZbEREW7
Bigger is possible but don't forget you also need to house a controller. With those 2 in my 'buddyseat' it's full so then you need to start modifying the structure of the body. I couldn't mount the controller in the original location since it's quite a bit bigger.
The difference in width is about 1cm I can probably make that fit. However the axle is 14mm on the QS and only 12mm original so I would need to modify the arm. Next to that I won't be able to use the rear brake anymore since the motor itself is to wide.
I have the motor spinning, but not properly and for some reason it hits regen extremely hard as soon as I want to go past 50kmph, no idea why.
@nardcox Indeed it's a big investment and goodluck in returning something to China 🙁
I want to pull a little bit over 20kW peak and 8-10kW cont with a 72v system (84v @ 100% SoC).
I'm using the same Samsung 29e cells as you got and since they have a rather low continuous and peak discharge I'll need a lot of them (for those who are reading they have 2.75 cont / 8.25 peak).
20kW requires 238A
8kW requires 95A
30p = 82.5A cont / 247.5A peak
35p = 96.25A cont / 288.85A peak
40p = 110A cont / 330A peak
Right now I have around 980 cells laying around so it's a matter of opening up the bike properly to see how much room I have to play with.
Indeed the controller is also quite a bit bigger then the original one and thus requires a different location. I thought about placing it in front of the foot pegs since the standard TC chasis allows for good airflow (see picture).
Although after seeing a recent picture of Wagner of his completely stripped frame, I have my doubts that the controller will fit in there. Might call for the pegs to be welded on in a permanent fixed position to get rid of that whole "adjustable by turning" style foot pegs.
If push comes to shove I will have to make it a naked bike so I can use up more room towards the sides. Only problem would be getting it checked by the ITV in 4 years time but that's a problem for future self.
1cm is indeed almost nothing considering it's only 5mm on each side but still too much for flexing the swingarm and forcing the motor in (metal fatigue is no joke and it will happen even when the material is never near pushed to it's stress limit. AvE did a great video on it quite recently: youtube).
I reckon that the easiest solution would be the following (I hope the picture loads in the right place).
Get that plate move more towards the outside of the swingarm. Of course you'd need some decent equipment for this including a welder.
Thinking about it whilst typing this I'd just remake that entire plate from some new piece of hardend steel (high carbon). In doing this you can make the plate thicker and thus stronger for the added torque of the motor, move it more towards the outside so that the motor fits perfectly and also make the 14mm shaft slot that you need.
You kill 3 birds with 1 stone which makes it worth looking for someone to help you in case you don't have this equipment yourself.
Another thing you can do it make the shaft 12mm either with a grinder or milling machine but honestly me personally wouldn't do this as it will greatly weaken the shaft (but I wanted to mention this option to you in case you're willing to take the risk).
Controller problem seems to be software related. Take into account that regen will feel A LOT more aggressive when the wheel is spinning in free air than when it has to regen with the bikes weight + the riders weight. Nonetheless trying to alter the software could be something you will sooner or later run into.
Unfortunately you're not near Spain since I'd love to help out in person but nonetheless I hope I gave you some new angles towards your problems 🙂
@bvzijverden, 8-10KW continous is hefty, you planning to go 100kmph+?
8KW = 95A is calculated with 4.2v per cell. Normally it's calculated with 3.6v because as soon as you start putting the cell under the load the voltage will sag. Next to that the battery should not be charger till 4.2V since that will hurt lifetime.
8KW / 72V = 111A / 2.75Ah = 20S40P
I have 400 cells and like I said the buddyseat is full, you will definately have to customize quite a lot then. The frame doesn't really make sense with a single tube, 2 parralel tubes would be better suited.
The location on the picture will be tricky. I know another member put a controller there and drilled some holes in the front for air circulation but the controller got wet, so be carefull there. I can't fit my controller in there, nor my charger.
I will check that metal fatique video soon, thanks.
Idea now is to mill 1mm away both top and bottom to make the axle go in, and then push the arm wide 5mm left and right.. That way I should be able to get the reakbrakes mounted as well.
Controller is definately software related, just don't know which settings... The test I did are with load, without load the tire can spin way faster.
