Lead Acid Battery Desulfation (ekm)
The jury is still out on how well this works.
There is plenty of anecdotal evidence that it works and a few studies also pointing to there being something to this.
This isn't a high priority but could be worth investigating.
These devices are quite cheap so on a RAP system - even a small increase in battery life will recover the cost.
http://p198.ezboard.com/Lead-Acid-Battery-Desulfation/bleadacidbatterydesulfation
So far I don't have any positive results to report - probably because the batteries I tried had other problems.
On the 9'th July 2007 I stuck a zapper on the large, big, old batteries I have at Nimbin. The zapper is a bit too small but it will be interesting to see if anything improves over the coming months.