AGM car batteries.




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  1. #1
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    Default AGM car batteries.

    I don't understand that some vehicles uses AGM batteries as primary batteries but you cannot connect a AGM battery through a solenoid as a secondary battery to run a fridge as it will boil it [apparently].Does the BMW's and Mercs have a different alternator or charging system to charge a AGM safely? So this also means if my battery in my Hilux say goodbye I canít replace the battery with a AGM because my alternator cannot charge it.
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  2. #2
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    Default Re: AGM car batteries.

    I have an AGM battery in my 2005 hilux for about a year now and everything seems fine......(as a crank battery)
    Put in by battery centre so I assume they know what they are doing.

    However checked the water levels the other day and they were low (3months ago) filled up and no movement since then.

  3. #3
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    Default Re: AGM car batteries.

    Quote Originally Posted by Lofty View Post
    I don't understand that some vehicles uses AGM batteries as primary batteries but you cannot connect a AGM battery through a solenoid as a secondary battery to run a fridge as it will boil it [apparently].Does the BMW's and Mercs have a different alternator or charging system to charge a AGM safely? So this also means if my battery in my Hilux say goodbye I canít replace the battery with a AGM because my alternator cannot charge it.
    Where do you get the AGM batteries cant be charged by alternators? I have read that these batteries are used extensively in the US in RVs, using "smart isolators", and that they are happy with a cars voltage of 14.2-14.4V. Certainly when I charge my AGM battery in the trailer with a smart charger on AGM mode, the NL monitor complains about overcharging condition.
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    Default Re: AGM car batteries.

    Quote Originally Posted by Ingetrap View Post
    I have an AGM battery in my 2005 hilux for about a year now and everything seems fine......(as a crank battery)
    Put in by battery centre so I assume they know what they are doing.

    However checked the water levels the other day and they were low (3months ago) filled up and no movement since then.
    Something about this seems wrong.

    Under the impression AGM batteries are sealed.

    Maybe pic of battery

  5. #5
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    Default Re: AGM car batteries.

    Quote Originally Posted by Prof View Post
    Under the impression AGM batteries are sealed.
    Definately

    https://batteryuniversity.com/learn/..._glass_mat_agm

    I do note this however, relating to the OPs question

    " Automotive charging systems for flooded lead acid often have a fixed float voltage setting of 14.40V (2.40V/cell); a direct replacement with a sealed unit could overcharge the battery on a long drive. "

    So it seems the float voltage is the problem.
    Last edited by SimonB; 2018/10/10 at 08:17 AM.
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  7. #6
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    Default Re: AGM car batteries.

    The reason why I asked is I want to go this route but my old deepfycle is almost past his date and them I want to replace it with a AGM.
    Quite a few posts in the last few week suggest that a normal solenoid system is going to cook the AGM and I dont want a R4000 doorstop.
    Last edited by Lofty; 2018/10/10 at 12:58 PM.
    2017 Hilux 2.4 SRX D/C 4x4 2012 Cross Polo [mamma s'n]

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  8. #7
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    Default Re: AGM car batteries.

    Quote Originally Posted by Lofty View Post
    The reason why I asked is I want to go this route but my old deepfycle is almost past his date and them I want to replace it with a AGM.
    Quite a few posts in the last few week suggest that a normal solenoid system is going to cook the AGM and I dont want a R4000 doorstop.
    I would suggest you need to investigate how your specific vehicle charges. Being a 2017 perhaps its alternator is a little more intelligent. I don't know, or look at a DC/DC charging system
    2015 Pajero Sport 4x4
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  10. #8
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    Default Re: AGM car batteries.

    Quote Originally Posted by SimonB View Post
    I would suggest you need to investigate how your specific vehicle charges. Being a 2017 perhaps its alternator is a little more intelligent. I don't know, or look at a DC/DC charging system
    No its not an intelligent alternator according to the internet and the clever people,I measured it at 14.1 V
    2017 Hilux 2.4 SRX D/C 4x4 2012 Cross Polo [mamma s'n]

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  11. #9
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    Default Re: AGM car batteries.

    According to this link you need and isolator to stop the charge from the alternator to the AGM battery to prevent damage.




    https://www.batterystuff.com/kb/arti...ry-basics.html
    Last edited by Lofty; 2018/10/14 at 04:36 PM.
    2017 Hilux 2.4 SRX D/C 4x4 2012 Cross Polo [mamma s'n]

    http://travel.webshots.com/album/558867451ncpSPZ

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