Charging lower soc 51.2v lithium battery directly from higher soc 51.2v lithium batteries.

[Pueo]

I have a 400AH 51.2v EG4 LL off grid house battery bank being charged by a Victron RS from ~5Kw of solar.
I am setting up a golf cart to run on a high amp BMS 100AH 51.2v lithium battery bank.


Can I safely charge my golf cart by plugging it into my house battery bus bars (with fuse) if my golf cart battery is at a lower SOC than my house batteries?

I may not understand this correctly, but my thought is that the house batteries' BMS will stop them from charging when they are full and the MPPT charge controller will keep charging the golf cart batteries until they are full.

If it is night time, and the MPPT is not charging and I plug the golf cart into the house system, wont the fully charged house batteries safely send current to the lower SOC golf cart batteries until they are all equalized?

If this is not advisable, I could always charge the golf cart via a charger running off of my inverter, but I think just connecting it to the house bank would be preferable if it is safe to do so.

Thank you in advance.

Ian

 

[timselectric]

Do not connect LFP batteries in parallel. Unless the voltages are within 0.5v of each other. LFP batteries are able to dump a lot of current, quickly.
If you're lucky, the BMS's will just shutdown. If not, stuff melts.
A separate charger is your best option, for the situation.

 

[Pueo]

Do not connect LFP batteries in parallel. Unless the voltages are within 0.5v of each other. LFP batteries are able to dump a lot of current, quickly.
If you're lucky, the BMS's will just shutdown. If not, stuff melts.
A separate charger is your best option, for the situation.

Thank you for weighing in.

by "a lot of current" do you mean well over 100 amps?

 

[timselectric]

Thank you for weighing in.

by "a lot of current" do you mean well over 100 amps?

Yes
A 400ah battery could easily dump 800a, at the time of connection.

 

[Pueo]

Yes
A 400ah battery could easily dump 800a, at the time of connection.

Gotcha, thank you!
looks like I will use a 120v charger.