Battery replacement

Kentsb
Kentsb Member Posts: 67
in Battery/Electrical & Solar
I will be replacing my Interstate SRM24 SLA battery. It turns out it is only 81 ah. I am considering going up to a 100 ah AGM. Is the extra 20 ah worth the effort to put in a larger battery box and added cost of $50 over replacing with the same. We always look for campsites with shore power first. If we do Boondock it is usually not for more than 3 days in the same spot. We have the factory solar. 




52 nights
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  • pthomas745
    pthomas745 Administrator, Moderator Posts: 4,530
    The only thing better than AH is more AH.  Depending on which way you read some reviewers/battery experts, the AGM's could (maybe) be brought down a little lower than 50 percent state of charge, so the increase in capacity could add an extra 40 amp hours compared to your Group 24 battery.  Those extra amp hours would mean an extra day of boondocking.  (You don't say what year your trailer is.)  So, yes, I think it is worth it, and I plan to make the same switch sometime this summer for my 2017.  The battery I'm looking at would need a bigger battery box, and it would appear to be able to fit in my Outback tub. 
    The thing I keep reading about AGM batteries:  they can be installed in any configuration except upside down. I might beef up the bottom of my tub slightly and have the battery "standing up" instead of flat, which would be an easier fit.
    2017 Outback
    Towed by 2014 Touareg TDi
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  • ScottG
    ScottG Administrator Posts: 5,655
    pthomas745 said:
    The only thing better than AH is more AH.
    ...
    Ha ha, I agree with that!

    @Kentsb, there are really too many variables to provide a simple answer. It depends on your needs (how much power you draw out) and on the reliability of full sunshine each day (how much power you put back in). In theory, you can boondock/dry camp indefinitely with your basic set-up, but I suspect you will have little margin if conditions are not ideal.
    2015 T@B Max S (320)
    2015 Nissan Frontier SV V6 4x4
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  • CrabTab
    CrabTab Member Posts: 457
    edited May 2021
    @Kentsb- Staring with a fully charged battery do you find that your battery is below 50% when you get up the first morning while dry camping? That would indicate the need for a bigger battery to me. If the battery is over 50% at breakfast but isn't fully charged by dinner time on multiple outings, look at adding more solar to meet your daily needs.  Like @ScottG mentions though, it can be a moving target...

    2019 320 Boondock Edge     - Sold Jan 2022
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