I bought a used forklift and the battery, even though only a couple years old, was almost dead from sitting too long without being charged. I got the lift to my shop and put a charger on it overnight. All seemed well, the engine starts fast and all that. So a few days later the propane ran out and the engine died. I got the propane tank filled that day and installed it the next day, When I tried to start the lift I realized I had left the ignition on overnight and the battery was dead. Again. So I put the charger on again and even with the switch in the 3 amp position the battery was drawing almost 15 amps. So a cell must have shorted out. Probably from sulfation. I watched the charger carefully and the current dropped to 3 amps after about 15 minutes so I figured the short must be gone. I left the charger on the 3 amp setting overnight. The next morning the battery was still drawing 3 amps. I then switched the charger to the 12 amp setting and let the battery charge until the amperage draw was down to about 6 amps. I then switched the charger back to the 3 amp setting and after about 6 hours the draw is down to about 1 amp. I left the battery on the charger overnight again and it is still drawing only about 1 amp. All the cells bubble slightly while charging at the higher current setting so I think they must all be charging. I have checked the fluid level in all the cells and none are low. In fact, they are all about the same level. After cranking the engine for about
60 seconds total in three tries the voltage of the battery is still
12.57 volts and during cranking didn't drop below 12 volts. The battery is the typical industrial type, long and narrow, not almost square like a car battery. After this long winded description I want to know how long should I keep charging the battery at the 1 amp level in order to remove as much sulfation as possible. Thanks, Eric