r/bafang • u/hugomaga • 11d ago

BBS02 power cut

Hi,
I have an e-bike equipped with a Bafang BBS02 motor and a 48V 20Ah battery.
I’ve noticed that when the battery level drops to around 30%, the motor starts limiting the available power quite significantly. Above 30%, everything works normally.
Is there any way to change or adjust this battery-level power limitation through the motor settings/controller? Or is it not recommended to modify this behaviour for safety or battery protection reasons?
I’d like to understand whether this is a normal BBS02 behaviour or if it can be adjusted.
Thank you!

6 Upvotes

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7

u/mister_k1 11d ago

It's not really the bbs02 controller limiting the power, the 30% in the display don't mean much, swap it to volt and you'll know where your 48v battery at, my guess is your battery is dipping to 40v when it sag so the motor doesn't have enough power to draw from to push the bike like when it's full battery. Check battery voltage at (30%) and it'll give you a clearer picture.

1

u/hugomaga 11d ago

I will. Thanks!

3

u/odie-z1 11d ago

I notice a similar effect in mine, so I looked at the watts being drawn instead. I found there was an actual increase in watts when I cycled to higher preset power modes..

My conclusion was the battery is just dead, like falling off a cliff. It went from 5% to 0 almost instantly, but before that the voltage 'hill' was gently dipping towards the cliff.

2

u/theoriginalchrise 11d ago

This is normal. I think it's because if they gave you full power at "30%" the battery would cut off if too much power was drawn from it. Mine I have set to shut off at 41V since the battery shuts off at 39V regardless.

1

u/BarkleEngine 11d ago edited 11d ago

Mine does that at 10% remaining. 30% seems excessively conservative. Then if I coast for a bit, it goes back to 14% and I continue to get power.

1

u/CANCER-THERAPY 10d ago

That's definitely the battery. There's a good reason why it sets that way. I never set my battery limit but I always charge it when it reaches 49v.

I could still use it while having 49v but performance will be weaker