therobby3 said:
@flippy I'm not really sure what drivetrain I would destroy with the motor. It's just the motor with a chain to the sprocket. The only thing it could really destroy would be to somehow shred the rear sprocket off the axle, which I highly doubt that would happen. I realize the motor itself puts out more torque, but by time you compensate for the gas engine's gear reduction (especially in first gear), I don't think it would necessarily be more.
you are miscalculating the forces involved, as i did many years ago with one of my first conversions. learn from my mistakes.
the highest tourqe that the motor can dish out happens at 0 rpm. your standard ATV chain will snap like dry spagetti and you will probably bend the rear sprocket and axle or a bit too loose chain will just strip the teeth off. at those power levels SOMETHING will move or give way. usually something expensive.
drivetrains are not made to handle such forces from a dead stop. this is why electric vechicles do NOT have gearboxes and insane reduction drives with sprockets you normally find in 18 wheeler gearboxes and diffs.
you need to double up the chain (offset by 50% of you can) or get some pHat aftermarket sprockets that can take a wider chain.
i managed to utterly destroy a drivetrain of a converted BMW E38 with a (utterly beautiful) M73B54 V12 engine that i replace with a DC motor from a forklift. the tourqe from the forklift motor was roughly the same as the original V12 but it still twisted that driveshaft like a piece of overcooked fusilli when i put my foot down. after replacing that and locking the gearbox in 3rd to keep the torque down it imploded the gearbox at half trottle. after that i removed it all and just bolted a steel driveshaft of a truck directly between the DC motor and the rear diff. wich ofcourse also exploded like a bomb within 20 miles.....
and that ENTIRE drivetrain was originally for a 500nm 350bhp V12 engine and had done 150k miles in 10 years without any issue and it would not even last for 10 miles with a 100bhp 500nm DC electric motor.
your new motor can do DOUBLE the torques and match the power output of what the original petrol motor could ever do at 3~5000rpm from a dead stop.
drivetrains CAN handle power, if you allow then to make LOTS of rpm like the petrol engines MUST make before the engine produces some torques. but a electric motor does the opposite, ALL the torques and none of the rpm. this is why a tesla reduction gearbox has a (roughly) 10:1 reduction ratio and STILL has 2 inch thicc gears inside. wich is roughly about the same width that gears inside 18 wheelers have inside their gearboxes. so truck gears in a 250bhp compact EV just to handle the forces.
this is why there is basically no EV on the market with a conventional gearbox. the gearbox would need to be lifted out a 18 wheeler in order to handle the power.
therobby3 said:
Yes I was probably planning on around 20 cells in parallel, which would put it around 15 amp max draw per cell. The specific cells say they are rated for 15 continuous, so I'd think a blast of 15 peak would be ok.
yes, that would be a good starting point. but you do understand that tesla cells have aluminium tops and are nearly impossible to weld properly?
therobby3 said:
Anyway, what I really need help with is exact specific parts, like links to them so I don't buy something wrong. I've bought these fuses, in 400 amps. I'm hoping these are correct ones that will work. https://www.ebay.com/itm/224057969036
megafuses are great. just get the original ones from bussman for example. trust me, those ebay ones are NOT trustworthy.
just search for ANL-400 bussman and get a supplier like mouser,digikey,farnell or whatever.
and yes, real fuses are that expensive. i know.
therobby3 said:
Also, what would I do as far as anti-spark connections? I converted a small dirt bike to electric at 72 volts, and sometimes connecting the battery without an anti-spark connector would result in a nasty spark. I used an XT90 anti-spark connector though, which is obviously way to small for my ATV build. What is everyone doing as far as anti-spark connectors for their builds?
Still wondering about some kind of main on/off switch that I could put right at the battery as well, that I could just push off and would prevent the power from the battery from going anywhere in case of emergency as well.
you dont need a anti spark connector, you connect to the contactor and that has a resistor across it to precharge the controller.
you put a fail safe rope thingy you put on your wrist and put that on the wire feeding the contactor. pull the cord and the contactor opens and it instantly kills the controller/drivetrain but keeps your 12V intact for lights and stuff so you remain visible.
therobby3 said:
Ok, good to hear the wait time from QS isn't always this long, incase I buy some other things from them in the future.
Yea, I'm hoping the controller is still plenty powerful though, so I guess we'll both see how things go.
Maybe I'm confused on something. I did a quick search and am not easily finding any BMSs that are 26s and can support at least 300amp. I would think, since my build will be 300 amp peak, that I should look for a BMS a little above that, correct? Like 350 or 400amp BMS? Surely it can't be this hard to find a BMS? ...I'm also curious as to why literally everything is from China. >.<
So your saying with a BMS, that I wouldn't need an anti-spark and would just turn off the BMS? I have a small BMS for a battery that I am working on for a small dirtbike, but as far as I know that BMS has no on/off switch or anything like that. Your saying these bigger ones likely would? Also, I thought the BMS would be stored internally with the battery once completed.
with currents like this you dont run the power over a million mosfets. thats just dumb and unreliable. once 1 fet blows you get a cascade and you blow up your entire board. forget that style.
you get 2 outputs on your battery: 1 with 96V "low power". that ones connects to your 12V and the charger. that actually goes over the bms but will probably only see a dozen or so amps during charging.
the other output is the "unregulated" power uitput that has a ANL-500 fuse on the inside of the battery as your "last resort". your ANL-400 (i would prefer a 350) is mounted outside the battery BEFORE the contactor. the contactor is powerd by your ignition key wich gets its 12V from a 12V converter that is always on from the low power output of the battery. the reason is simple: your ignition key is NOT rated to swich 110V DC. it will arc and kill itself and probably weld itself closed so you cant turn the ATV off. so you make 12V and switch that. you can ofcourse have a separate swich that can take 110DC to power off the 12V.
ps: get the JK-B2A24S-20P bms. its a LOT better then the ANT bms. https://www.aliexpress.com/item/4000529723243.html
it has active balacing and all that goodness.
ps: for connectors you just use anderson SB175 for the main unregulated side and a smaller SB50 for the regulated side that goes over the bms for charging. donr forget to get some of those rubbber boots for them to prevent muck from getting in.