Although I can't prove it, my lead-acid batteries do seem to last longer since I started using an activator circuit. The principle behind this Activator for Lead-acid Accumulators is very simple. The battery is charged with a current of about 100 A for a period of 100 µs, which is repeated every 30 seconds.
The theory is that short (large) current pulses will reverse any sulfation of the lead plates.
Not only is sulfating prevented, but these types of peak current can also be used to determine the quality of batteries.