Forum Discussion

KeithAS's avatar
KeithAS
Explorer
Nov 08, 2015

Battery Connections

I started opening up the rig today, trying to find a way to run DC power to a couple of places inside. I think I have a handle on a work around for that.

My question revolves around the batteries. The rig came with one, and the dealer installed another before I took delivery. The two are connected, positive to positive, and negative to negative, like I would have expected. However, the power to the rig was off of one battery, not from positive of battery 1 and negative from battery 2. Does it matter?

Now, a minor editorial rant. These batteries require periodic maintenance. The battery boxes and vent tubing require a good deal of effort to access, and one could plan to take about an hour to complete the job. On top of that, the boxes are in no way sealed, plus the vent tubing popped off as soon as I lifted the lid (fastened with what appeared to be electrical tape).

9 Replies

  • pianotuna's avatar
    pianotuna
    Nomad III
    Nov 08, 2015
    Hi Mr Wizard,

    Balance also makes a difference when charging. And if you are a generator charger then you want to shove in as many amps as you can.
  • MrWizard's avatar
    MrWizard
    Moderator
    Nov 08, 2015
    For the milliamps of the fridge control board, makes no difference
    However for a three way fridge with 12v power operation, which requires over 20 amps, yeah that needs to be balanced

    It is very odd for the fridge to be connected directly to the batteries
    Fridge let should be coming from the 12v fuse panel aka power center
  • azrving's avatar
    azrving
    Explorer
    Nov 08, 2015
    Remember that this stuff is very addictive and it goes on and on and on. I dont know how involved it is to do the battery box rebuild but you may want to consider your possible future modifications like maybe more batteries or 6 volt batteries which are taller. Will you be boondocking and want more amp hours on hand.
  • KeithAS's avatar
    KeithAS
    Explorer
    Nov 08, 2015
    Thanks, I may go ahead switch the cables. Also tempted to build a single battery box for both.
  • 3oaks's avatar
    3oaks
    Explorer
    Nov 08, 2015
    KeithAS, my TT came wired just like yours. I never changed it and am still using the same two batteries for almost ten years. Didn't know it made any difference until reading similar threads a year or so ago and doing some research. :@

    How much more could I have asked of these two original batteries no matter which way they were wired? :R

    However, when my new TT arrives, I will be making sure the two batteries are wired the "preferred" method for proper balance.
  • pianotuna's avatar
    pianotuna
    Nomad III
    Nov 08, 2015
    While what is there is safe it is also not optimal.

    This is what is balanced and best for twin twelve volt batteries.



    As it often doesn't cost a dime more to do this, I think it is worth the trouble.

    If you wish to understand the "why" surf here:

    correctly interconnecting multiple twelve volt batteries

    Others may say it doesn't matter--but unless there is a compelling reason to not optimize charging and discharging why not do it the best possible way?

    Here is a video of 3 twelve volt batteries that have been wired in an unbalanced manner for 2 years. They have been equalized. The test shows how CCA has been adversely affected.

    unbalanced for 2 years
  • azrving's avatar
    azrving
    Explorer
    Nov 08, 2015
    Balance. Pos to one, neg to other. It wouldn't seem to matter but it does.
  • 2oldman's avatar
    2oldman
    Explorer II
    Nov 08, 2015
    KeithAS wrote:
    However, the power to the rig was off of one battery, not from positive of battery 1 and negative from battery 2. Does it matter?
    There are two schools of thought: Yes, and no. I lean toward the no but have no issue with the yesses.

    To really see if it matters in your case, voltage measurements can be taken each week of each battery.

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