Tuning your RXV for a Lithium Battery

[TheCartBoy]

Would depend on his specific battery and charger. I would think the 80% charge limit would have to be set by the charger, by setting a less than full voltage limit. Otherwise ya how would the BMS know the difference between a charger or regen currents.

[Oneunder]

Originally Posted by TheCartBoy

Would depend on his specific battery and charger. I would think the 80% charge limit would have to be set by the charger, by setting a less than full voltage limit. Otherwise ya how would the BMS know the difference between a charger or regen currents.

The charger may be easiest. Most have a little potientiometer inside that can be tweeked.
With the BMS I was thinking to set the cell over voltage protection at 3.65 v. and then set the active balance to start at 3.35 v. with trigger voltage 0.001v

If your charger goes til 3.65v (full voltage) and then is shut off by bms or charger, the BMS will continue to active balance until it hits the 3.35 v threshold.

Should work unless the user starts back driving before the balance phase completes or your charger is the kind that starts back up when the cells settle - which would require the user to unplug the charger after completing the charge to all for the balance phase.

[georgia088]

To clarify on this, if the charger interlock is bypassed which you don’t recommend, the brake resistor voltage needs to be set slightly above the chargers output voltage. So, if the charger’s output is 58.4, a braking resistor value of 58.5-59 would be best? I plan to add the interlock back, but will have to order a relay.

Thanks for this!

[TheCartBoy]

Yes that's my suggestion. Also note, since your multimeter and the controller might read voltage differently due to calibration, once the battery is fully charged, keep the charger on and turn the cart on, look at the key switch voltage displayed in the monitor menu, you'll want to make the resistor turn on above this level.