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23mikey's avatar
23mikey
Explorer
Aug 11, 2015

Inverter Wiring Length

Hi All,

Installing an inverter / solar / battery upgrade to my 2015 Glacier Peak 5er. This will be the 3rd system I've installed in 3 different 5ers and each one I've incorporated lessons learned and knowledge gained from this form to improve each one.

My question focuses on the wiring from the battery bank (4-6v AGM) to the inverter. Cable will be 4/0 and the batteries will be within 3 feet of inverter.

QUESTION: How critical is it to have the total length of the negative cable the same as the total length of the positive cables? I know to have balance of the battery bank will require me to take power off opposite ends of the bank. In my situation my batteries are mounted on two shelves, one on top of the other. So running the NEG cable from lower fwd batt and POS from upper rear Batt will have cable lengths 12-18 inches different. Will this cause an unbalanced condition? Should I just add an extra loop to equalize the lengths? Or am I over thinking this and it's not to worry about?

Thanks,
Mike

14 Replies

  • The engineers at Magnum Energy seem to think it's important, there must be some sci-ency stuff behind it. I've seen similar mention to "balanced" wiring in other high-end inverter manuals.

    My guess is the issue is not with power transfer efficiency, it's more about the inverter's low-bat voltage sensing circuit... in terms of lead acid state of charge, millivolts count.
  • With 2 12 volt batteries cable length to the load doesn't create imbalance. With 3 it becomes an issue and equal length cable to a buss bar is the solution.
  • No, there will be no imbalance IF they connect to the batteries in a balanced manner. The current through each cable will be the same. Ohms law indicates that in a series circuit the current remains the same while voltage drops across any resistance.
  • I do not see how there would be any in balance. At 0.04901 Mohms/foot, there virtually no electrical difference in the lengths you are talking about.

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