I guy on a solar forum had some inverter issues and now need to mount external 48V chargers on his/or his customers batteries. He’s saying he’s got a $300/ea budget so gonna be used most likely.
Req were 120VAC input on a 15 or 20A circuit and must take batteries up to 56.8V and then hold at 54.0 - 54.4V
Doesn’t have to be DeltaQ but I know some of you guys collect programmable cart chargers.
LMK and I can connect you up.
It might take a while to get +18 of them. DQ is a bit overkill. Probably better to point him to something simpler.
There are bunches on Alibiba. probably cheaper too. They usually offer to program them for your needs.
Oopsie…
Nothing like buying solar panels to charge the power banks from a wall socket. Efficiency at its finest. DC to AC to DC… Instead of DC, he should consider Marvel. Its less dark. Get it? 
some on the forum are just load shifting so don’t do solarPV recharging and others don’t have enough panels for Winter season because of roof space restrictions, costs, etc so there can be weeks when recharging from the grid is needed. Lots of options but yes, some of use are off-grid too doing what most people think of when they think solar PV + batteries.