Well its been a while since I made an update to this bike, but I'm doing a couple things.
New motor!
After much contemplating I've decided to order the high-torque version of my QS motor. I was wanting the torque from the start, and I don't want to go 85km/hr on this plastic ebike. 60km/hr top speed with high torque is fine for me. Speaking with Robert from QS he has told me in the past it can handle 4kw nominal and about 7kw peak. He also recently confirmed the motor can take around 100amps which at full charge 84v = 8400watts. Since this is only for a few seconds when taking off (especially with the high torque motor) he said this should be fine
Upgraded battery
I've decided to give lay the modular battery blocs battery to rest. It added quite a lot of weight to the battery 6.84kg! (15.1 LBs)
Since 200 cells is approx 9kg (19.84lbs) this is a huge amount of weight to add (43.18% of total battery weight is just battery blocs)
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I've was never sure about the resistance of the magnets and the plates. Also now that I've taken it apart, I've noticed the 3D printed plastic has warped since the cells generate some heat, over time the plastic warps, some of them have split (problem I had from the start). I really expected a higher quality product, but I guess saving money on injection molding is worth it for him. Oh well- i'll probably just give them away to an enthusiast in Toronto, they can be fixed with heatgun I'm guessing, probably about $400 in total hardware there.
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So the new battery will be using nickel strips and spot welding. My current 20s10p pack of LGMJ1 3500mah cells (200pcs) I'm going to add 100 cell (Panasonic PF 2900mah)
Both these cells are rated at 10a each. Although the capacities are different, I'm going to add the extra cells to each parallel group so that each group will have the same capacity and power output.
The new battery will be 20s15p
10 cells of MJ1 + 5 cells of PF (for each group)
I'm going to make them as two 36v 10s15p packs connected in series because I'm not going to add a BMS. I will balance charge each pack with my iCharger 1010B+ balance charger when they need balancing
I mocked up cell spacers the configuration so I could get the sizing right. Each layer is 36v 10s15p, going to connect them together with some 6AWG and PRC8 connectors. Will put a sheet of acrylic between them + tape & heatshrink etc
Kelly controller settings
So it occurred to me I was never getting the full power from my battery because of my Kelly controller. The battery current limit in the settings of this controller max value is 80% which means I'm only every getting 80% of the power from my pack
my 20s10p pack could do 100amps, but I was only ever getting 80amps
Also I noticed my cheap chinese 84v charger had somehow gone down to 80.7v
So if the charger was working properly 84v at 80amps = 6720watts for the "balanced" version motor (balanced torque and max speed is 85km/hr)
But really I was getting 6456watts
aaaannyways. My new 20s15p battery will require me to program kelly max battery current to about 67% because new battery can output 150amps. As per Roberts recommendation I don't want to send more than 100amps to the new motor
Bonus 1: I have a larger pack 49.5AH
Bonus 2: Each cell has to work less - instead of doing their max 10a per cell. To make 100.5a they only need to do 6.7a each.
Bonus 3: This battery can be used with higher power setup in the future
So after extracting all the batteries from the batteryblocs one I'm balancing every single cell before I build. I made a little 10s balancer holder. The left box is staging area for each battery group - you can see the PF 5 cells at the end.
Bike re-wiring
I thought I was being super smart by using a shitload of little connectors when doing all the bike wiring. Turns out I was wrong, when it rains water drips down the small wires into the small connectors and causes corrosion. This would mean sometimes my lights wouldn't work, sometimes horn would't work. Sometimes my 12v key switch to precharger to contactor wouldn't start the bike!!
Solder and heatshrink going forward