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rugercpl
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# Posted: 15 Oct 2015 11:20am
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This time of year I don't get the direct sun like I do in spring and summer so I supplement battery recharging with my small Honda generator and a Schumacher XCS15 (15amp) recharger. I can't speak on the quality or performance of this recharger as its my first and only one. It does the job but it seems like it takes a long time to recharge my battery bank of (3) 100ah AGM batteries. When the batteries are drained to 60-70% power, reading 12-12.3, it can take the generator and charger around 10-14hours to get the batteries back up to a nearly full charge at 13-13.1. Is that normal?
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MtnDon
Member
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# Posted: 15 Oct 2015 02:29pm - Edited by: MtnDon
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If the three 100 AH batteries are in parallel then you have a 300 AH, 12 volt battery bank. A general rule of thumb is to try to charge at a rate equal to 10% of the total AH capacity. That would be 30 amps. BUT, what is the maximum charge rate recommended by the battery manufacturer? If the mfg recommendation is less than 30 amps go with that. IF the mfg states you can use a higher rate then go for that.
A reasonable cost charger would be one of the Iota Engineering DLS models. They do not have the best power factor but they are reasonably priced. If you know a electronic "pot" from a cooking pot you can also tweak the output voltage upwards to achieve a more rapid charge. Mine are tweaked to where I can do a decent EQ with the quick charge plug inserted. Backwoods Solar also sells some they tweak. Costly when they do that though.
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creeky
Member
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# Posted: 15 Oct 2015 05:27pm
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my thoughts exactly. 30 amps seems reasonable. i've also seen powermax chargers a bit cheaper than the iota. they have a "boondocker" model.
14.4 absorb to properly charge the agms? i don't know. check your manual.
at 60-70% discharge tho. you're probably better off charging sooner for lower discharge.
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groingo
Member
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# Posted: 19 Oct 2015 11:15pm - Edited by: groingo
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I have used a mess of them and in the end your batteries dictate how much juice they will take which seems to be in my case 15.2 amps max which after an hour will have dropped to 9 amp and in another hour will hover around 5 amps for the duration of the charge.
As said, check your battery manufacturers spec sheet for max charge rate because the charge times for the percentages you mentioned are right in the ball park from my personal experience.
Another thing you want to check is the solar panel charge controller input voltage settings, my controller is a $19.00 wonder but lets you adjust your minimum and maximum voltages( which has a huge positive effect on input amperage...for example 13.6 volts gave me a max amperage of around 5 amps but at 15.2 volts I can get up to 20 amps) but be sure if you disconnect the controller from the batteries that you re-set your charge rates or they will drop to default which in my case was a max voltage of 13.6, once I figured that out it has been smooth generator free sailing on the crummiest days and I have dismal solar exposure!
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