Charge 48V (FLA and LFP) batteries from main 48V LFP battery bank?

[wpns]

I’ve got four golf carts with various combinations of flooded lead acid and LFP batteries, each of which is on the order of 3-10 kWh capacity.

I am about to install six EG4 PowerPro wallmount batteries for a total of ~86KWHR LFP storage.

Obviously I can charge my golf carts at night by the simple expedient of plugging them into 110 V outlets. However, that feels kind of inefficient.

Is there such a thing as a 48 V to 48 V battery charger? I’d like to be able to pick a maximum current in the range of 15 to 30 A, and have the charge shut off when a particular voltage is reached. Would the lead acid batteries need some kind of multi stage charger for more than occasional use?

And of course, if I could swap the inputs and outputs around, I could use the golf cart batteries to recharge the house batteries in an emergency.

Anyway, just sort of mulling this over and wondering if there’s already an off the shelf solution to this.

Thanks!

 

[crossy]

It really depends just how "DIY" you want to go.

Plenty of DC-DC boost converters on Ali-Express for pretty small money.

Set the output to your chosen float voltage and the current limit to what you want to charge at and away you go.

Something like this: -

https://www.aliexpress.com/item/1005005973066920.html

I'm sure someone actually makes a "charger" with displays etc. I just didn't spot one in my cursory search.

 

[sunshine_eggo]

You'll lose about 20-25% DC-AC-DC.

You'll lose about 10-20% DC-DC, and any quality solution is likely to be inferior to your existing charger and definitely more expensive.

Lead acid batteries need at least two phase (bulk and absorption) charging and preferably three phase (bulk, absorption and float).

Charging to a set voltage and then terminating is a GREAT way to shorten the life of the lead acid batteries. They need to reach true 100% SoC as often as possible and floated there between uses.

Operating voltage of FLA is mostly below LFP, so there's no recharging, but they could run the system. FLA fully charged is about 12.6-12.7V, and when you load it, it drops. LFP is at a very low state of charge at 12.7-12.8V - less than 20%.