Float and absorb settings for Duracell AGM 155ah batteries

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Float and absorb settings for Duracell AGM 155ah batteries

Postby Dondario on Thu Apr 11, 2019 11:23 am

I’ve just recently installed 4x 350watt panels to my offgrid house system. I cannot find any information on the manufacturer suggest charge, float, and absorb settings. Using a FlexMax 80A charge controller through a Schneider 4024xm inverter. Currently set at absorb 28.6V and float 27.2V. Kind of a newbie but I’ve been onhand with the entire install. Do these numbers sound correct? Today it’s a bright sunny day and the max80 hit the absorb around 11:40 am and is currently in a 2hr absorb time. Any suggestions would be greatly appreciated. Thanks
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Re: Float and absorb settings for Duracell AGM 155ah batteri

Postby Gwendoly Espe on Fri Apr 12, 2019 2:26 am

Hello,

It's the batteries that need charging and the setpoints should come from the batter manufacturer. Here is an example of one of ourBatteries Datasheet and you can see the setpoints. You must find the datasheet for your battery manufacturer or call them so get these setpoints.


Here is a YouTube video about Best Practices for Charging OutBack Batteries that has some information that can be applied to products other than OutBack.
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Re: Float and absorb settings for Duracell AGM 155ah batteri

Postby raysun on Fri Apr 12, 2019 6:09 am

Your profile shows 12 155Ah batteries in a 24V configuration. Is each battery monoblock 6V or 12V?
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Re: Float and absorb settings for Duracell AGM 155ah batteri

Postby Dondario on Fri Apr 12, 2019 8:03 am

Batteries are 12v 155ah 540wpc
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My RE system: Schneider 4024 inverter outback flexmax 80 charge controller 4x350W 24v solar panels 12 Duracell 155ah 24v

Re: Float and absorb settings for Duracell AGM 155ah batteri

Postby raysun on Fri Apr 12, 2019 9:33 am

12V monoblocks in a 24V battery bank would have to be wired as 6 parallel strings of 2 monoblocks in series. Conventional practice is to have no more than 3 parallel strings in a battery. With 6 strings, it will be difficult to keep each monoblock at the same state of charge. Some strings will be slightly more conductive and work a bit harder. Some strings will accept charge more readily. (It won't necessarily be the same strings in both cases.) Eventually, the strings will be out of balance to the point that monoblocks may fail prematurely. Using an equalizing charge may help correct an imbalance to a degree, but EQ charging is hard on AGM batteries, and also can substantially shorten their life.

From a battery maintenance standpoint, it would have been better to use a 48V inverter and wire the battery bank as 3 parallel strings of 4 12V monoblocks each.
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My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
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Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Float and absorb settings for Duracell AGM 155ah batteri

Postby Ravens Roost on Fri Apr 12, 2019 9:40 am

Duracell (big) batteries are made by East Penn. I could not find much info for Duracell but did manage to find East Penn AGM deep cycle info: http://www.eastpenn-deka.com/assets/base/0139.pdf . See chart on page 11. Looks like setting for batteries at 70 to 80 Deg F is 28.6 absorb and 26.8 float. Page 10 has a chart with life cycle info, do not expect a looooong life with these as deep cycle batteries. Good luck.
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