HELP. My motor is barely moving me. It had plenty of speed yesterday but today it is only going ~5mph

General Discussion
21

Adding to this. When I let my battery get that low, my BMS decided it’s not worth charging. So I would plug my charger in, it turns green instantly, and the pack stayed “dead”.

Ended up having to bypass the bms and charge direct into the discharge lead for an hour before swapping back to using the bms to balance out and finish the charge. Checked the specsheet for my bms and sure enough, this cheap chinese bit of junk won’t charge my battery if the cells drop below 3.3v (was at 3v, yea I know but I wasn’t about to push home)

Everything is fine now, but if your charger light isn’t turning red, try bypassing the bms for a bit.

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22

What do you guys recommend then for complete cutoff voltage? Looking at graphs of 30Q discharge it would seem that 3.1V would be a good point to stop. (Many on this forum use 3.2V)

23

Thats a preference thing. the higher the safer and better for the battery but how often do you run your board till it stops? I don’t personally. Battery anxiety is a real thing. lol

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24

Dont personally what? Either you mean the battery anxiety = range anxiety, or you mean the overall health of a cell :thinking:

25

Was I texting in turkish again? I do that sometimes

26

Damn. I think this is happening to me. Could you speak a little more about how you bypassed the bms? Should I disconnect the bms all together and then charge it and then reconnect the bms?

27

So I run charge only bms. (Hence the 2 output options) Since you have charge/discharge on the same connector I would just unplug the battery to bms connection and send the charger power direct into the battery. Bms would be disconnected at this time.

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28

So this is my BMS, how would you use these wires to bypass it? IMG_4209 IMG_4210 IMG_4211

29

Looks like the red (assuming positive) wire of the battery is connected directly to the cells, so it’s the thick black wire (assuming negative) that is going through the BMS. You’d have to solder the 2 thick black wires together temporarily to charge your battery, but I’m not sure if it’s safe to leave everything else in place while you do that. Someone more experienced with BMSs and this scenario should step in and guide you. (i.e., don’t take my word for it, wait for someone else to chime in as well.)

30

So in that last picture it is actually after I have soldered the thick wire. The thick wire is the boards power, where the thin wire is the charging cable. I disconnected both of those from the bms and connected them directly to the other side and it seemed to work but now the charger is showing green as if it is fully charged again

31

What did you have to fix exactly?

32

It was just my phase wires but you have a battery issue, and I have absolutely no knowledge on batteries

33

I am still not sure what issue I am having. Was it the soldering of your phase wires or was it something else? I soldered my phase wires to the vesc wires instead of getting connectors.

34

That might be your problem, I really have no clue though

35

What was wrong with your phase wires?

36

One was disconnected

37

Sorry to keep harping on this but was it 100% disconnected or just partially?

38

Partially attached

39

So when I get on the board and try it, it says 100% before I accelerate, but once I begin the battery percentage continuously goes down to ~5% within about 5-10 seconds. Does this sound like the same battery problem to you?

40

Thought I’d got rid of you!!! How long was it on charge for? Did the battery indicator rise to 100 Did the charge light go from red to green? Does the board work? Lolz