posted 4 months ago
No, out of my wheelhouse.
You have six batteries connected in series to make that 36v. Means in general, that the batteries 'closer to the discharge' do a little more work and those 'farther down the line' get a slightly lower proportion of the charge. If you follow the solar forums, there is a lot of talk of battery balancing, even folks building their own equipment to charge such setups to within a few hundredths of a volt.
If you want plug in wall simple, then sourcing an original type charger or repairing yours would be the way. Those chargers are fairly simple, I think. If yours has failed likely the power supply is defunct. Could be easily fixed if you live where a tech or hobbyist can be found. Throw away society has banished them.
If you have solar DC available, then DC-DC chargers are available.
If you want slightly more work, then temporarily break the string up into three pairs of 6V batteries, one cable each, and charge/recondition each pair with any 12V battery charger. Mix them up if you like balance them out.