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Small Cabin Forum / Off-Grid Living / Just Dont Understand---Battery Charger Question
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hitanktank
Member
# Posted: 25 Jan 2013 16:20
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So lets say I have a deep cycle AGM battery for a solar setup, but need to charge it with a charger. I just dont get what kind of charger is required for deep cycle batteries. Cant a person just put a trickle charger like a car battery uses? Ive read stuff on chargers for this but all Ive seen is too technical talk.

Can someone dumb it down for me please?

MtnDon
Member
# Posted: 25 Jan 2013 17:44
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A trickle charger is designed to be a maintenance charger. It puts out a low current at a lower voltage than used for recharging. A more correct name would be a Float charger; that fits into todays terminology better. The 3 main stages are, Bulk, Absorb and finally Float. There is also Equalize but that is never done with an AGM. A float charger is not suitable for recharging a depleted or partially depleted battery.

Whether or not the battery is a deep cycle or not does not matter. What does matter is the manufacturers charging specifications. Most AGM can be used with a regular charger as would be used for a flooded lead-acid battery. But some AGM batteries have a lower voltage recommendation. Check that out and compare those values against the specs for the charger. It is important to match the voltages.

TomChum
Member
# Posted: 25 Jan 2013 23:40 - Edited by: TomChum
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A trickle charger is used AFTER a battery is fully charged. It replaces the power that a battery loses by "sitting", called "self discharge". Just to keep the battery "topped off".

It might take weeks (if ever) to charge a large battery with a trickle charger.

silverwaterlady
Member
# Posted: 26 Jan 2013 04:18
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How do I maintain the charge on my marine batterie that I have stored in my basement?

TomChum
Member
# Posted: 26 Jan 2013 11:36
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SWL, get a charger that has a 15A, and a 2A. The 2A is the "trickle charge" function. I would get a modern charger that is advertised as "Fully automatic".

Your battery won't last long if it sits in a discharged state. Its ideal to charge it to full charge at first opportunity then 'maintain' the full charge with a trickle charger. A fully automatic charger will do this process all by itself, you can just leave it all hooked up full time.

MtnDon
Member
# Posted: 26 Jan 2013 12:49
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Sometimes charging with a cheap trickle/float charger can do as much harm as ignoring the battery over the winter. An engineer friend bought several Harbor Freight chargers on sale a while back. He found the output voltage on all three to not only be different but they varied in use. All three put out too high a volatge most of the time to be considered safe for extended use. So, caveat emptor.

A good charger is not cheap. For regular rechsarging of a depleted battery it is best that the maximum bulk and absorb amperage be no more than C/8 to C/10, where C = the rated amp hour capacity of the battery. Less than that is okay, charging just takes longer. If a generator is the AC source that wastes fuel.

As I said before check the battery mfg specs and try not to exceed their recommended float vlotage with the charger you buy.

hitanktank
Member
# Posted: 26 Jan 2013 17:17
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thank you all much--I now understand better and will check specs then get a proper charger

littlesalmon4
Member
# Posted: 28 Jan 2013 12:07
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my battery charger analyzes the batteries. It then charges at the best voltage and amperage.

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