Regen - AC-F4

[VP_EV]

Hello,

I have a 48V AC F4 controller. I am facing an over-voltage error during regeneration. I have tried to limit the regen power and current but I guess the voltage is rising beyond a certain threshold and the BMS switches off suddenly leading to a motor short error.

Has anyone faced such problems before?

Regards

[TheCartBoy]

Yes, common problems with an undersized battery or BMS. We see it all the time here with folks that buy cheap lithium batteries or put several 12v lithiums in series.

[VP_EV]

The BMS can handle 80V. Is there a workaround for this problem ?

[Volt_Ampere]

The BMS is protecting the battery from over voltage. One solution is to not charge it to more than 80%.

[VP_EV]

I didn't get your point. Battery is at 48V when fully charged. The BMS can handle max 80V.

Originally Posted by Volt_Ampere

The BMS is protecting the battery from over voltage. One solution is to not charge it to more than 80%.

[TheCartBoy]

Does the battery shutdown if you push too much current? Maybe it's not the voltage limit that's tripping it as the root cause.

Could try not charging the battery as much, gives more head room.

Also adjust the overvoltage protection lower, so it limits regen.

Also consider adding a regen resistor like the RXV to soak up that extra energy.

https://www.buggiesgonewild.com/showthread.php?t=194038

[Volt_Ampere]

Doesn't matter what voltage the BMS CAN handle. It's PROGRAMMED to protect the battery from over voltage. That is not going to be set at 80V!

[TheCartBoy]

That's right. He needs to understand the BMS protections, it could be 1 cell's voltage is too high, that could happen well before 80v on the entire pack. It's also possible it's an overcurrent or over temp protection all of which could happen below 80v.

[VP_EV]

Okay. Understood. I will take these points into consideration.