Shadow:
The batteries are used and you need to "rebuild" them, this is exactly what I have been assisting a fellow in the west coast of Canada with his 3 strings of 24 volts 395 amps that were going to the dump in short order.
You need reconstruction and you will need a hygrometer and a DVM voltmeter to do it
The EKV ( Equalizing Knee Voltage) may be around 2.48 to 2.51 volts/cell, the way to determine is to take charging voltage readings at 0.1 volts steps with a charger with carefully adjustable output voltage and read the reduction in current and at certain voltage drop you starts to see a drop in current.
The charger can not be set as constant current source or the reading will be not shown.
All the lead batteries are LEAD ACID BATTERIES no exception, some have antimony, some have calcium, ETC.
You need to limit the current to 20 % of amp-hour and keeping a good temperature track and stop when the temp reaches > 115 F .
Replenish water as needed, discharge to 1.75 volts/cell and do the re-charging up to 3 or 4 cycles maximum, you should stop the cycles once ALL the hygrometer readings reach 1265.
Then charge the battery to 2.4 volts/cell then when the current lows to about 4 to 6 % of amp-hour switch the charging voltage to 2.3 V/cell that for a 48 volts is going to be 55.2 volts = = float charge voltage.
Once a month recharge to 2.48 v/cell to keep the equalization UP and to "reduce" the sulfation, stop when temp = 115 F.
Nando