Bulk/Float Voltages for AGM Batteries?

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thatguy
thatguy Registered Users Posts: 7 ✭
in Solar Beginners Corner #1
I am attempting to calibrate my Xantrex C60 charge controller for 2 AGM batteries (31DTMAGM, 105 AH each) .
I can't seem to find any spec sheets on what voltages the battery needs, nor any consistant data online related to the C60 in this context.


Anybody got a chart, a specsheet, a reference of any kind would be great. Been scouring the net all day.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
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    Re: Bulk/Float Voltages for AGM Batteries?

    welcome to the forum.
    what i found is somewhat vague for you to follow, but it does give some parameters.
    http://www.driveduracell.com/default.aspx?pageid=14
    it basically says a max bulk/absorb setpoint of 16v, but is most likely closer to normalized regulator outputs of many alternators. maybe try 14.4v to 14.8v with the middle of it at 14.6v as my best guess.

    they don't specify a float voltage as most alternator/regulators do not have a float stage. i would hazard to say the float could be between 13.4v and 13.8v and my choice would be 13.6v. as the regulators on boat alternators usually have a constant voltage output of about 14.1v to 14.4v, like many cars, that you see the initial charge i said is much higher and then is backed off lower for floating.

    this is pretty much of a good guesstimate of what you may be looking at unless somebody finds something more specific.
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  • thatguy
    thatguy Registered Users Posts: 7 ✭
    #3
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    Re: Bulk/Float Voltages for AGM Batteries?

    Well, that page is closer than anything else I could find today. I couldn't even find anywhere Duracell claimed ownership over the product.

    Meh, I am still hoping to find some more precise numbers from them, I sent a couple places some emails, it's a long shot.


    *edit*

    According to this thread http://www.thehulltruth.com/marine-electronics-forum/483564-duracell-agm-batteries-what-charger-do-i-need.html The 31DTMAGMs are relabled "Deka Intimidator AGM's with a Duracell label.....but warrantied by Deka."

    And according to this http://www.dekabatteries.com/assets/base/1740Intimidatordeepcycle.pdf it is likely that its actually the Deka 8A31DTM. All the specs match up.

    So I have a new search vector, which is promising.


    *edit*

    So I found the following
    Bulk: 14.4 - 14.6 -- midpoint of 14.5
    Float: 13.5 - 13.8 -- midpoint of 13.65

    My question now is, where in the range should I charge, does being on the upper end of the accepted range shorten the life or capacity of the battery bank?

    IDK, seems like there should be an easy to digest charging specification guide, if it exists I would love to brush up on this.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Bulk/Float Voltages for AGM Batteries?
    thatguy wrote: »
    My question now is, where in the range should I charge, does being on the upper end of the accepted range shorten the life or capacity of the battery bank?

    Voltages within the specified range will have no significant effect on battery life or capacity. The small variation between the high and the low is a tolerance factor to account for the differences in whatever meter is being used to measure it. It is not possible to even make a setting that precise in the real world.
    IDK, seems like there should be an easy to digest charging specification guide, if it exists I would love to brush up on this.

    That would be the day! There are thousands of different AGM's and FLA's out there, with variations on the theme to the extreme including alterations in shipped SG for climate conditions and adjustments for application. It will never be easy to digest, much to our chagrin. :roll:
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  • thatguy
    thatguy Registered Users Posts: 7 ✭
    #5
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    Re: Bulk/Float Voltages for AGM Batteries?

    The Xantrex C series charge controller has excellent fine tuning for these voltages, I was able to set both bulk and float to the exact mid-range of accepted values before sunrise this morning. Though I think you are right about the measuring tolerances of different meters, I shall check with a different meter when the chance presents itself.

    Thank you guys for your help with the matter.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
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    Re: Bulk/Float Voltages for AGM Batteries?

    you're welcome for what little help we provided. i would be curious as to where you found that added info and does that match the specs for the deka?
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  • thatguy
    thatguy Registered Users Posts: 7 ✭
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    Re: Bulk/Float Voltages for AGM Batteries?
    niel wrote: »
    you're welcome for what little help we provided. i would be curious as to where you found that added info and does that match the specs for the deka?

    See here: http://www.federalbatteries.com.au/8A31DTM/

    and a decent specsheet of batteries and their charging voltages and specs here: http://www.federalbatteries.com.au/files/charging.pdf

    The technical specs on the deka intimidator match the specs for the duracell 31DTMAGM exactly, both batteries are made by the same manufacturer, and they match up by eye as well, minus the different branding stickers. This, plus the 3rd party information posted in another thread, which I pasted here in a previous post, lead me to believe they are indeed the same physical battery, and the voltages for the intimidator should be applicable to the 31DTMAGM.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #8
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    Re: Bulk/Float Voltages for AGM Batteries?

    very good then. go with those charge parameters then and notice i wasn't too far off in my guesstimate.
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