Charging AGM batteries - a question.

I'm using ex-UPS AGM batteries because they're cheap (6x12v = 72).

My old charger was made for floodies and never switched to float with the AGMs, I thought there was something wrong with it. I had been keeping an eye on it and turning it off after about 4 hours, all went well until the inevitable, I forgot. The batteries virtually turned to jelly after being left on overnight. An interesting smell too!



Now I have another set of AGMs, and I got another charger too, however it's one for flooded lead acids again. I've tried it and like the old charger, after a while the voltages climb too high to be safe for AGMs (16v each when they only want 14.7v). And again it didn't switch to float. Admittedly I only left if for four hours, but by then the voltages were unsafe for the AGMs and they started to get hot.

Kelly HWC4B 72V/15A


So here's the question(s) -

1. Will my AGMs never tell the charger it's time to switch off? (just out of interest)

2. Is there a clever way I can fool the charger to avoid overcooking the batteries?

The Kelly has 3 lights to indicate state of charge, when light 2 goes on the voltage is perfect of the AGMs, it would be nice if it went to float then.

Thanks.