48 volt ebike battery diagnostic, battery cuts out when used with a 1000watt contoller
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- Опубликовано: 26 авг 2024
- "When you think you can get away with using the wrong battery, wrong cells and tape and glue...you're in for a shock 🤦♂️ #faultyebikebattery #donttrythisathome #ebikebatterypower"
I ran into this myself, it's an education in pain haha.
@13:50 I like how that data sheet uses mAh for current. Lol. But in other parts of the datasheet it gives the proper mA current unit. Other datasheets also give it a 2c continuous rating and 3c max discharge (for acceleration).
While its a weak battery for that application, i think the problem is a little deeper, and you can’t see on that bike without checking top balance, draining the pack, and checking bottom balance. A smart BMS would show the problem very quickly.
Since we know those cells can deliver 8250 mA, and it’s 5p, thats 41a.
We also know a 48v 1000w controller is not 20a peak, it’s probably 30a peak. Thats the number we need to see.
But assuming 30a peak, 35a bms, 41a cell max, i would assume there are some dead cells in some odd the cell groups.
Since we know those are low drain cells, probably ran at too high a discharge for too long, it’s quite likely he popped a few CIDs, and severely degraded the cells. A smart BMS would show this as soon as you rode the bike.
Any battery can be top balanced as long as at least 1 cell in each group is still alive. Even if that 13s5p only had 4,3,2 or even 1 cell working.
We also know a dumb BMS won’t balance a pack that suddenly had a cell die, because the BMS reaches OVP before the charger current can taper down. I suspect someone got in there and manually balanced that pack without checking for dead cells, which is nearly impossible.
I had a 13s5p battery with dumb BMS and I thought everything was fine until I put an ANT bms in it. Then I could see cell differential climb during acceleration and also that same outlier brick was dropping faster as the pack drained.
Turns out one brick has a dead cell. Not shorted of course but the CID popped, so it just sat there quietly. Lol.
Eventually i clipped the nickel on the positive bus one cell at a time until i found the cell whose voltage suddenly changed. Of course it was the last cell. Lol. But i cut it out and slid in a new cell and welded up the bus again and now it’s working fine. Still a 💩 25a cdr battery, but working fine.
If you had a way to load test that on your workbench and then check voltage sag, I bet one was sagging down and hitting LVP early.
That battery patched up can work fine on that bike if he uses another similar battery in parallel (not with some electronic splitter).
Anyway, just my speculation because that battery probably already had the fire department called on it. Lol
Right cells for right setup. 🙂
Sometimes I come across with the same issue. If somebody don't know what he is doing can cause big problem. Luckily in this case the cells didn't blow up, even though the BMS temp sensor was only on top of the battery pack.
Good spot with the temp sensor placement and yeah customer requested a samsung 35e based battery
The cells are 8000ma spike. They must have gone off of that or only had a 35a bms laying around. So if you ever rebuild your battery you have a bigger amp bms to use. If your controller is more than 14 amps and run at full throttle that in it self will drain your battery fast. Maybe your controller is cutting off your battery at low voltage.
It looks like a bomb
I have a 48V 1000W motor and a controller of 15A rated current and 30A maximum current with a battery of 54V 12.5A (BMS 35A MAX CONTINUOUS DISCHARGE)
The motor spins freely without issue but on load it accelerate to about 15km/Hr the power cuts off, display refreshes (l am clueless if it"s the BMS or controller cutting off power and why]
Pls help
If they did a top balance wouldn’t they have had to open it to disconnect the bms? So are you deducing that its the wrong battery for the bike because your assuming the BMS is probably OEM and therefore the controller was for a 1000watt bike and trying to draw up anywhere up to 35 amp. So I’m guessing that its ok to use that BMS on a 14a battery, but you have no protection for the battery since the problem is its not big enough, relying on battery shutdown for either temperature or low voltage shutoff?
I have a question I bought an aliexpress battery that says 50amp but it gets discharged very quickly in about 15 miles and this battery is smaller than my 48v-18 amps how can they say its a 50amp battery?
What a mess!
I wouldn't have even opened a pack like that. Very low audio on this vid, btw.
Its Oct 2023 and sound is good.