Mex's 20% AGM Rule Sucks.
Mex says deep cycle AGMs need to be recharged at a 20% of Bank AH rate even if they are not Lifelines (which do specify that). My AGMs are not that brand, and no mention is made of a minimum charg...
Forum Discussion
I have faith that my AGM spec sheet/user guides are honestly meant.
The 100AH ones say for "cycle use" to recharge at "27A or similar" at 14.5 to 14.9 "control voltage".
The 250AH one says for "cycle use" to recharge with "constant pressure" at 14.10 to 14.40 v and, "the initial current is smaller than 100A"
They both want the recharge to be "constant voltage" method. The 100AH one could be read as saying they want the current to be about 27A no more no less. I have been reading that 27 as being the Max with no Min specified.
The 250AH one is clear they mean 100A is the Max and no Min is mentioned.
When banked, I use 14.5 volts as near enough to be common to their specs. When doing them individually, I use their own specs as above.
I don't have the data collection to observe if they are gradually losing capacity like LY or full_mosey does to know when they need a good goosing and then see the benefit from that. I just do it "every so often" which is also what the user guides (and Mex) say, sort of.
I run my "10 hour" capacity tests at their 20 hr rates at least once a year. Another quick test is whenever I do get down to 50% camping near as I can tell, (12.4 volts for "morning voltage) the Trimetric AH counter does say approx 225AH down, which is a match. I compare AH count with voltage to notice if anything is wrong.
I am one of those solar types now that Mex mentioned, who mostly only do shallow cycles despite lots of microwaving etc, with no attempt to conserve. So like Mex says, you have to go out of your way to meet this not- in- the- user- guides- 20%- recharge- rule, but it can be done "every so often" without too much pain.
The 100AH ones say for "cycle use" to recharge at "27A or similar" at 14.5 to 14.9 "control voltage".
The 250AH one says for "cycle use" to recharge with "constant pressure" at 14.10 to 14.40 v and, "the initial current is smaller than 100A"
They both want the recharge to be "constant voltage" method. The 100AH one could be read as saying they want the current to be about 27A no more no less. I have been reading that 27 as being the Max with no Min specified.
The 250AH one is clear they mean 100A is the Max and no Min is mentioned.
When banked, I use 14.5 volts as near enough to be common to their specs. When doing them individually, I use their own specs as above.
I don't have the data collection to observe if they are gradually losing capacity like LY or full_mosey does to know when they need a good goosing and then see the benefit from that. I just do it "every so often" which is also what the user guides (and Mex) say, sort of.
I run my "10 hour" capacity tests at their 20 hr rates at least once a year. Another quick test is whenever I do get down to 50% camping near as I can tell, (12.4 volts for "morning voltage) the Trimetric AH counter does say approx 225AH down, which is a match. I compare AH count with voltage to notice if anything is wrong.
I am one of those solar types now that Mex mentioned, who mostly only do shallow cycles despite lots of microwaving etc, with no attempt to conserve. So like Mex says, you have to go out of your way to meet this not- in- the- user- guides- 20%- recharge- rule, but it can be done "every so often" without too much pain.
