So far my desulfator experiment hasn't gone great. I'm desulfating one 18AH 12V battery from an old jump pack. It's gotta be close to 15 years old. I'm also desulfating 3x 20AH 12V batteries from an old Xantrex Xpower inverter setup. These are about 10 years old. I'm charging all the batteries in parallel using the Xantrex charger that came with the inverter setup. The negative connection is on one end of the battery string and the positive is on the other. To check the capacity, I've using an electronic load I borrowed from work with a battery test function. I've set the cutoff voltage to 11V and due to the jumper wires that I'm using and the very poor condition of some of the batteries, I've had to set the test current to 1Amp.
Battery #1 (jump pack battery) test results:
Test #1 3.07AH
Test #2 2.95AH
Test #3 2.85AH
Battery #2 Inverter battery #1:
Test #1 0AH, ran about 10 seconds under 1A test load.
Test #2 0.18AH
Test #3 0.14AH
Battery #3 Inverter battery #2:
Test #1 0AH. Cannot support the 1A test load. Battery voltage drops to ~9.5V when the test load is applied.
Test #2 0AH, ran about 5 seconds under 1A test load.
Test #3 0AH, ran about 10 seconds under 1A test load.
Battery #4 Inverter battery #3:
Test #1 3.41AH
Test #2 3.9AH
Test #3 3.73AH
Mixed results so far. I've been desulfating the batteries for 8-12 hours at a time, recharging and checking the capacity. To speed things up, I've been desulfating battery 1 & 4 or battery 2 & 3 connected in series to save time. The desulfator I bought does 12V/24V/36V/48V and autodetects the battery voltage. Since the desulfator is self powered, it will only run for a few hours on battery 2 & 3 (low capacity). To save my time testing, this weekend I connected all four batteries in parallel and hooked up the desulfator the same way I hook up the charger. I'll check it in a few days.
This is the desulfator I've got:
https://www.amazon.com/cleanpower-Batte ... 134&sr=8-4
The only downside to this model so far is it discharges the batteries and will hit its low voltage cutoff on low capacity batteries.