Lithium pack with electric parking break

[InVision]

Testing a lithium pack with my carts electric parking brake. No issues until I get under 30%. The lith pack abruptly went down and the brake engaged at 20 mph. Pants check scare. Not sure what to do. Is it the BMS or the cart that engages break when power drops. Work around is to always charge at 40%. Anyone point me to info on this would be most appreciated.

M

[jasonojordan]

When you lose pack power the parking brake engages. Does not have anything to do with the BMS. FLA carts do the same thing.

[InVision]

Thanks for the reply. I was thinking there was someway in the BMS not go from 50v to 9 volts instantly.

[TheCartBoy]

So is the reported 30% SOC actually 0%? Like the gauge needs a recalibration.

Or does the BMS behave differently at 30% SOC, like a reduced current draw limit? That would be atypical.
Perhaps what happened is you mashed the pedal and one of the cells voltage dropped and that triggered the protection fault.

I have some tuning info for the RXV about this. The undervoltage protection on your Curtis controller could be adjusted to work better with your battery.
https://www.buggiesgonewild.com/showthread.php?t=194038

[InVision]

Thanks for the info. Pretty sure it was not a fault as the battery reported 0% when it started to charge and charge normally from there. The battery came with a display. I was on my way home and the last I looked it was reporting ~30% or so. I was not hitting the go petal much because I was in a 15mph speed zone. clue in the data that can help. Have not seen any recal settings in interface. But you might be right that it need recalibration setting 30% as 0%.

Thank you Cart Boy !!. You have always been a huge help on this forum.

M

[InVision]

Originally Posted by TheCartBoy

So is the reported 30% SOC actually 0%? Like the gauge needs a recalibration.

Or does the BMS behave differently at 30% SOC, like a reduced current draw limit? That would be atypical.
Perhaps what happened is you mashed the pedal and one of the cells voltage dropped and that triggered the protection fault.

I have some tuning info for the RXV about this. The undervoltage protection on your Curtis controller could be adjusted to work better with your battery.
https://www.buggiesgonewild.com/showthread.php?t=194038

Thank You CartBoy !! I am starting to look at this. Here is the only reading on my programmer that I found with undervoltage. *see photo.

FYI-The battery tech support re-calibrated my battery remotely.

This is the only undervoltage that I could find in the manual. *see photo

Should I use 97% for Undervoltage? 46.4v/ 48v

Should I use 115% for Overvoltage?

Thoughts?

M

[TheCartBoy]

You are looking at monitor values on the handset, those are read-only statuses. It's the parameters page you want to change.

Underv 46.4v sounds like a good start point
Overv 58.4v would be my start point, essentially no regen allowed when at full capacity.

[InVision]

Yea way different...

[TheCartBoy]

Yep those are the ones. So do the math to get the %. Plug those in, then test it out with the battery low and full charged. The monitor cutbacks you showed previously will let you know when the underv or overv protections are starting, the percent will change from 100 down to 0.
Play around with the numbers to better understand how it works and dial it in for your battery.

[InVision]

Is there something else I have to set? It won't let me go above 80% on undervoltage. Volts per cell maybe?

Thank You