2 6v Battery Minimum State of Charge

I see many of you say that your battery level at its highest is 12.5 and it should never go below 12.1 or so, but my batteries 2 6 volts (232 amp hours) is at about 13.5 at it's highest. How do I figure out what is the lowest I should let it go. I've searched on the Internet and can't find the information.

I have a 2018 320 CS-S so I have the digital seelevel. At this point I'm mostly plugged into shore power, but I'd like to know for the future.

Also, I was plugged into 30 amp shore power all last week and the battery level stayed at 13.1. I drove it home 4 hours and it was up to 13.5 by the time I got it home. I'm assuming the 7-pin charged it or it reads differently depending on where it's plugged in. At home it's plugged into 15 amps with an adapter, but of course it's alone and not sharing the park with many others.

Any information people experienced with these batteries have would be great.
Aileen & Muggles (and some human children too) @ 2018 CS-S currently called The [email protected] Pod  @ TV 2004 Toyota [email protected] Massachusetts


  • ScottGScottG Posts: 2,210Moderator
    edited August 2017
    After charging, batteries will typically show a high residual voltage of over 13V. However, this should dissipate to a lower number within a couple hours of sitting unloaded.

    That said, a good battery may hold a charge of 12.8V for some time. I would even argue that a battery that settles in closer to 12.5V after a full charge is probably getting a little long in the tooth.

    As for the lowest voltage, 12.1-12.2V seems to be the conventional wisdom. That corresponds to about 50% of battery capacity. Regularly going below that causes cumulative damage to the battery, reducing its ability to hold a charge and shortening its useful life.

    I'm speaking of batteries in general here. I don't have the same high-capacity set up as you, but the basic principles should be the same!
  • jcfaber1jcfaber1 Posts: 308Member
    I would recommend getting a Trimetric meter and a shunt installed.  You then program in your AH capacity.  The meter will then know your percentage of charge, whether charging or discharging and by go much.  Having this type of meter is the only way to know how your battery is doing.

    2007 [email protected]

    Rockford, IL

  • geekmamageekmama Posts: 59Member
    @jcfaber1 that sounds interesting. I think it would be more important when I start camping without shore power. I was just wondering so I could stay aware.
    Aileen & Muggles (and some human children too) @ 2018 CS-S currently called The [email protected] Pod  @ TV 2004 Toyota [email protected] Massachusetts
  • Sharon_is_SAMSharon_is_SAM Posts: 2,799Moderator
    Geekmama, to approximate your battery charge using the SeeLevel you need to unplug from shorepower and turn off anything that can draw power from the battery - frig, lights, fan, CO/ LP detector, etc and turn your battery cut off switch to the battery " on" position.  Then after at least 30 minutes or several hours later check the level.  On the other hand, if you just want a rough idea, there are plenty of people who get by with a simple gauge that reads from the 12 V plug and gives pretty much the same reading as the SeeLevel.  So, if you are constantly on 120 V and also charging with the 7 pin, you are probably not drawing down your large capacity batteries very much.  The fact that they can achieve  a 13 V charge is good, too.  But the RESTING charge of a fully charged 12 V system is 12.6 to 12.8 V.  Northern Arizona Wind and Sun has an excellent FAQ section on deep cycle batteries and that will help get you the info you need.  I agree with jcfaber1 - you need a better meter with a shunt to really know the true charge of your batteries. 

    Cleveland Heights, Ohio
    2017 TaB CSS / 2015 Toyota Sienna Minivan

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