Forum Discussion

SpeakEasy's avatar
SpeakEasy
Explorer
Aug 08, 2018

Charging a 12V AGM Battery

I've been researching various options for replacing my Walmart 12V sort-of deep-cycle battery. I've pretty much decided that a single 12V AGM would be the right choice, given my budget and electrical usage.

My question is about charging.

I currently have a 100-Watt solar panel and a Morningstar SunSaver PWM controller. The controller came with instructions for setting it up for EITHER a "sealed" battery type or a "flooded" battery type. There is a jumper that is installed between two terminal blocks if you want to set it up for a sealed battery. You do not install that jumper to use it with a flooded battery. I did not install the jumper.

If I buy a 12V AGM, do I just install that jumper and go on with life? Or is there more to properly charging a 12V AGM? What about the times when I have to use the generator for charging? Does the trailer's converter need to be replaced in order to do this? If I plug in to shore power and there is no sun, will the existing converter be OK?

Thanks in advance.

-Speak
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Aug 09, 2018
    And the panel has to deliver to the battery not to the entire rig 20% of the amp hour rating of the battery. Easier said than done.
  • full_mosey's avatar
    full_mosey
    Explorer
    Aug 08, 2018
    The two charging Volts of the SunSaver PWM are 14.4 flooded and 14.1 sealed.

    I set my SS PWM to 14.1V during the summer otherwise to 14.4V for my AGMs before upgrading to the SS MPPT 15l controller with automatic temperature compensation.

    HTH;
    John
  • Sam_Spade's avatar
    Sam_Spade
    Explorer
    Aug 08, 2018
    SpeakEasy wrote:

    If I buy a 12V AGM, do I just install that jumper and go on with life?


    Yes, yes and yes.

    The conventional chargers that you have should be just fine.

    You might end up with your AGM charged only to 95% instead of 100; no big deal.
  • BFL13's avatar
    BFL13
    Explorer II
    Aug 08, 2018
    You also need to know how and have the ammeter for, charging an AGM to full and know when it is full. RVs don't come with that ammeter for one thing.

    If one 12v will do you, IMO just get two 12v WalMart flooded ones for the same price as the one AGM. You get way more AH, you won't be deep cycling as deeply, so the battery will do better just from that (shallow cycles are easier on the battery), and you don't need to fuss with or learn anything about AGMs.

    I have gone AGM for various reasons, but I also have the ammeter, the right charger, etc, and the time to take care of the AGMs. It is not the same as having Flooded batts. I have done it both ways.

    I went to AGM because I need to have them inside the rig, where fumes from Flooded batts are not acceptable. Otherwise, I would have stayed with Flooded.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Aug 08, 2018
    IF (and it won't) my Lifeline died tomorrow...

    I would have paid FIFTY DOLLARS PER YEAR for it's service
  • time2roll's avatar
    time2roll
    Nomad
    Aug 08, 2018
    SpeakEasy wrote:
    If I buy a 12V AGM, do I just install that jumper and go on with life?
    Yes.

    Need the converter model for additional comments.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Aug 08, 2018
    A bunch of data is missing here to see how your system interacts

    • How is your panel used?
    • In conjunction with a converter or solo?
    • How deep do you discharge your battery before recharging it?
    • Do you boondock camp? For what length of time?
    • When you return home do you connect to shore power?
    • How many weeks per year do you boondock?


    This info is critical in determining whether or not you unintentionally kill an AGM through improper usage. Three years service is a heck of a lot more costly than seven or ten.
  • dougrainer's avatar
    dougrainer
    Nomad
    Aug 08, 2018
    AGM's would be classified as a SEALED battery.
    Depending on the brand/model AGM will determine if your Power Converter is correct for a particular AGM. General rule is, Power Converters will charge AGM's at the correct rate. The only time you need to worry about a charger is, if you have an Inverter/Charger. THEY usually have Flooded/AGM charge rate setting parameters. Your solar will not cause any problem with the AGM, once you install that jumper. Doug

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