small draw even in tow

[dc.901]

Hello folks,
I am looking for some tips/tricks/advise on how to troubleshoot this small draw that I am seeing - even when the switch is in tow mode.

My cart and battery:
2003 Club car DS
Cart is lifted
Bigbattery NMC 80Ah batteries.

If I fully charge the batteries (50.4v), over night it will drop 0.5volts - this is with switch in tow mode

If I completely unplug the batteries from cart, the voltage does not drop at all, it will stay like that for days. So, that make me think it is not the issue with battery but something on cart is drawing small power.

I do have a 48v to 12v transformer for lights.

Oh and incase if it matters, weather wise, we're just outside of Atlanta, GA. We've had few cold nights, but nothing as drastic as some folks in North.

Any advise will greatly appreciated...

Thanks!

[Volt_Ampere]

Use your multimeter in ammeter mode to measure the draw. Disconnect one terminal and insert your meter in there with the cart in tow and measure the current. If you are seeing Lithium batteries drain, then something is drawing current because they won't self discharge like FLA batteries do. It could be your reducer if it's always on.