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
When AGM batteries are DEEPLY cycled
How did the word DEEPLY get edited out?
DEEPLY is 50% or less charge contained in the battery.
Diddle with an AGM with several dozen 25% discharges and take too long to recharge and the battery will start losing capacity. It's cumulative.
THEN! Discharge the battery to 40-50% of capacity
THEN! Whamjam as much amperage at "vAbs" as the battery will accept to a limit of 14.4 volts until one half percent of amp hour capacity is reached.
What did I write about Telecom batteries? About them having thick mats and calcium in the plate? They have their own set of idiosyncrasies. The basics still apply but their design is to offer long standby life, an occasional zot down to 40% with an expected "soon" full recharge.
Telecom batteries come with boilerplate instructions. Those instructions are to make the battery and the manufacturer look as good as possible. Do they use a generator to recharge? No. Are they cycled weekly? No. Do their owners chit chat and say "My xbarfie brand battery lasts an average of 11 years. How about yours?"
IF the battery cannot accept 20% of amp hour rating, one of two things is going on:
a) The battery is at the bottom of a shallow cycle, too full, and absorbsion voltage limit causes less then 20% fill rate.
b) The battery may be less full than what the limited amperage would indicate. Batteries that have lost capacity because of sulfation do this. It is up to the owner to find out why. Discharge another 20% and if the battery barely makes 20% it needs to be conditioned not merely recharged.
REMEMBER! Batteries that spend lots of time at 60% to 80% full will need to be drawn down and 20% recharged or if this has gone on too long, they may need a conditioning cycle. The closer and longer you can keep the battery to 100% filled the less the loss of capacity will appear. This doesn't mean to not cycle the battery, it means the battery cannot screw around at 50-80% for weeks on end.
I do not make the rules. The battery does. Shout at it.
How did the word DEEPLY get edited out?
DEEPLY is 50% or less charge contained in the battery.
Diddle with an AGM with several dozen 25% discharges and take too long to recharge and the battery will start losing capacity. It's cumulative.
THEN! Discharge the battery to 40-50% of capacity
THEN! Whamjam as much amperage at "vAbs" as the battery will accept to a limit of 14.4 volts until one half percent of amp hour capacity is reached.
What did I write about Telecom batteries? About them having thick mats and calcium in the plate? They have their own set of idiosyncrasies. The basics still apply but their design is to offer long standby life, an occasional zot down to 40% with an expected "soon" full recharge.
Telecom batteries come with boilerplate instructions. Those instructions are to make the battery and the manufacturer look as good as possible. Do they use a generator to recharge? No. Are they cycled weekly? No. Do their owners chit chat and say "My xbarfie brand battery lasts an average of 11 years. How about yours?"
IF the battery cannot accept 20% of amp hour rating, one of two things is going on:
a) The battery is at the bottom of a shallow cycle, too full, and absorbsion voltage limit causes less then 20% fill rate.
b) The battery may be less full than what the limited amperage would indicate. Batteries that have lost capacity because of sulfation do this. It is up to the owner to find out why. Discharge another 20% and if the battery barely makes 20% it needs to be conditioned not merely recharged.
REMEMBER! Batteries that spend lots of time at 60% to 80% full will need to be drawn down and 20% recharged or if this has gone on too long, they may need a conditioning cycle. The closer and longer you can keep the battery to 100% filled the less the loss of capacity will appear. This doesn't mean to not cycle the battery, it means the battery cannot screw around at 50-80% for weeks on end.
I do not make the rules. The battery does. Shout at it.
