Good explanations above, thanks. My own "use" is "cycling" but they are on a "float" otherwise between camping sessions. My float is just to maintain them. It is not a "use" like "standby", but has the same "charging voltage" spec as "standby" has in the mid to high 13s.
In previous threads it seemed to come out that there are two kinds of "telecom" batts, depending on whether acid- starved or not. If "telecom" batts are Gel, then is it correct to say any AGM is a "telecom" battery, even if it is in "standby" use by a phone company? Are there in fact two kinds of AGMs?
