wrote in message
...

For long slow discharge, in a device with the proper charge
controller
for Gel use, the Gel is still a (reasonably) good solution. For
heavy
loads, not so good. For high charge rates, not so good. For mobile
high vibration use, not so good - and they DO require a specially
programmed charger. Do NOT charge gel batteries with a normal
flooded
acid or agm charger. A pure lead AGM battery is almost always a
better choice.

Good advice.

While searching for a comparison of flooded, AGM and gel float
voltages I found this:
http://www.windsun.com/Batteries/Battery_FAQ.htm

I charge all types except NiCd and NiMH with a lab supply, and use it
to temporarily recover old NiCd tool packs that have dropped to zero
and won't charge on an automatic charger, and to reform old
electrolytics.

Lead-acids reveal their state of charge by the increasing voltage
needed to force a constant current into them. I get the endpoint
topping or float voltage from the maker's data sheet, or for flooded
cells by measuring the specific gravity and watching for bubbles in
all cells.

I've noticed that the fully charged and endpoint voltages are about
0.2V different for two identical SLA31 batteries bought a year apart.
The cause could be manufacturing differences in the plates, or
variations in the volume or concentration of the acid.
jsw