A/B Marine Battery switch

[dehoov]

I'm running two 48 v batteries for the winter commutes, and right now I'm cycling in the morning on Batt A, then physically pulling the Andersons apart and plugging in Batt B for ride home.

Can I use my marine batt switch to make this easier? Switch is rated 48v with "A" "B" "A+B" and "off" . It has three bolt connectors - Batt A, Batt B, and "common".

If this works, I assume wiring is: Pos red from bat A to "A" bolt of switch, same for B, both black neg from batt come together outside of switch, and to controller, positive from common of switch to controller. Good?

 

[dnmun]

you can wire the batteries together in parallel and then put a switch on the circuit current for the BMS for each pack and turn either one on or off as needed. but it is better to leave them both connected in parallel all the time. and turned on. if one pack cuts out for LVC then you can turn off that BMS and use the remaining charge in the other pack which will be minimal in any case.

 

[dehoov]

Thanks dnum.
Well, I'm not going to crack open the bms to install switch at that point - one batt already has a key switch but the other does not. My tech capacity is good for crimping andersons but that's bout it. I'm not sure why it would be better to leave parallel all the time as opposed to running each battery solo for half the day's commute. Both batts start the day at 54v, and end between 49.5 to 50, depending on wind etc... I have the marine switch, so I thought it would be easy way to avoid reaching into the bags and fiddling with andersons all the time. Also, when switch is off, then don't have to pull andersons apart to charge?

you can wire the batteries together in parallel and then put a switch on the circuit current for the BMS for each pack and turn either one on or off as needed. but it is better to leave them both connected in parallel all the time. and turned on. if one pack cuts out for LVC then you can turn off that BMS and use the remaining charge in the other pack which will be minimal in any case.

 

[Punx0r]

If you run with both batteries wired in parallel then you halve the load on each battery, which improves efficiency and reduces wear on the batteries.

 

[dnmun]

if you charge a pack with a BMS in parallel with another with a BMS then you have to separate them at the P- lead when charging to allow the HVC on either BMS to function properly.

but you can leave the C- and B+ leads connected in parallel and even use the one charger.