I found a bunch of 48v ebike batteries that wont charge. How do I diagnose whats wrong with them?
>>2955654(You) don't. if you don't know how to diagnose them, you have no business messing with them.
>>2955654Give it back Jamal.
>>2955654disassemble and test each cell
>>2955671What are you even doing here?
>>29556541) Find a swimming pool containing water 2) Throw ALL ebike batteries into that pool 3) Record what happens 4) Upload results to /gif/ or here if you must so we can then instruct you further.
Okay I'm in.
So far it looks like this one had poor contact on the charge port. Charging up now
Did op die in an explosion?
>>2955852i like you
I had one once where the temu spec USB charging port (which was always connected directly to the battery, couldn't switch it off) drained the battery to the point the internal BMS disconnected the cells, the charger wouldn't charge it. Opening the case I managed to jump the chargers output directly to the cells bypassing the BMS for just a second or two, increasing the voltage enough for the BMS to reconnect so then the charging port worked normally again.
>>2955654open it up and check the voltage of each individual cell. if they drained too low you might be able to recover them by charging it slowly but they will always be unreliable and discharge quickly even if they take a charge again.
>>2955727Battery and battery management systems are something you need relevant experience for, they turn into a rocket engine in your eyes or explode when you do something wrong.Also nobody with experience with these things will risk recharging a fully discharged lithium battery because they have a high chance of exploding just from being recharged.
>>2956949I wouldn't say you absolutely need experience to work with such things. I've constructed three battery packs with just some minor instructions. As long as a person doesn't short something out, it's pretty simple. With that said, lithium batteries, especially packs reaching beyond 30v, should be given more respect. As for fully discharged packs, I'd say to just charge in a minimal risk area like a concrete pad. If it blows, it does so where it can't make an even bigger fire.
>>2955727trying to keep morons from dying. I realize that I probably shouldn't.
>>2955848
>>2956855most likely, and nothing of value was lost.
>>2956954translation:>I agree OP should stop messing with shit he doesn't understand.
>>2956961Eh, I wouldn't go that far. Maybe move to less spicy packs first, and go up from there. Just recently rebuilt a Prius battery pack at roughly 220v. Not dead and the car has done about 200 miles since. A guy gains a lot of respect for how much juice he's working with when shorting just one cell. Respect is what keeps someone alive.
>>2955694This. They need to be within a tenth of a volt of each other. All of them should measure the same with no more than one off by a tenth. The entire pack is limited by the bad cell. Drove an EV car with one bad cell. Took range from 250mi to 90mi. Replaced cell and all good.
>>2957949Wait, so at 100% charge, did it still say 250 miles or 90 miles? My car battery drains too fast.
>>2957962Who cares what it estimates? Driving the car is the only real measure. My car always tells me 430 miles, and hits E at 400.
>>2955654They make great incediaries. I safely dispose of lithium batteries by shooting (22LR so they don't scatter) then scrapping the metal slag with other metals. You can snap cells in half held in a bench vise etc (I wear my welding PPE) or similar too. Everyone who enjoys working with lithium batteries should have personal experience with how they ignite and burn.Ebike batteries have made some nasty residential fires. I do not store my solar power batteries in any structure I care about nor would I work on lithium batteries anywhere but my all-steel welding shop.If a large pack burns no extinguishers cannot put it out and if that pack is automobile size you lose the building. That's not paranoia. https://www.youtube.com/watch?v=gPxvTTWvwb8When cells outgas under thermal runaway they'e basically chemical weapons. This gent trains other firefighters and is both a Captain of an FD and an engineer. https://www.youtube.com/watch?v=4E3y7pwB6W0Shipping BEV by sea is so dangerous to car carriers Matson quit doing it despite the revenue. Batteries look comfy in a satisfying electronic way, but don't trust that with your home or life. Morning Midas, Fremantle Highway (which survived but was sold to Chinahttps://maritime-executive.com/article/salvaged-fire-damaged-car-carrier-fremantle-highway-sold-to-china ) and Felicity Ace are what happens when BEV batteries ignite. Even if something else ignites batteries once they're burning indoors you're fucked. That's why I'm hunting a castoff solar road sign trailer to gut and make into a mobile (technically) solar power unit I can place a safe distance from my structures without a permit since it would be like any other mobile jobsite solar rig. I store the usual small lithiums in a small industrial flammables locker they can't melt through and in steel ammo cans (lids left loose for venting until I drill lids for screened vent bungs). Electronics are fun but never guess, study seriously and play safe.
>>2955654Open them up. They probably just have one or two bad cells in them that need to be replaced.https://www.youtube.com/watch?v=iDrz5zhNxz4
>>2958217Yeah I tried that with an electric bicycle pack from my brothers. I replaced a couple cells, and tried charging it, and kept having cells fail to the point that half the batteries in the pack were bad. I tried salvaging the rest but after testing them they were just done.
