For your power tools, Try charging at 700 MA. I tried the high charge rate and it did what you're saying. I use the Triton on all my power tools. Makita drill,Skill power screwdriver, Sanyo vacuum, etc. Lead acid batt. may be to high of a rate too. My 20 AH field charging batt. I charge at only 1.3 amps otherwise it cuts out to soon.