I have two powerpro batteries and wanted to add a third. My question was can the battery cable from the parallel batteries be different lengths? I read that the lengths should be the same on paralleled batteries. And is there a max distance with the wire size that is provided with the powerpro? I attached a photo of my system I’m setting up. I’d like to put a 3rd powerpro on the right side of the door(where mirror is). And run the wire under the step and to the master battery. I would have to make longer cables to reach. I contacted eg4 via email with same question but haven’t gotten any response so I figured someone here probably has an answer or have had a similar problem and a solution.
Powerpro design question
- Thread starter Bricktop
- Start date
MisterSandals
Participation Medalist
Having equal length battery cables (both +'s the same, both -'s the same) helps each battery receive the same current flow. This and proper balanced wiring (diagonal vs from one end for example) is also crucial.
MisterSandals
Participation Medalist
If it were me, i'd probably give it a go as specified but use a larger wire size to offset some of the added resistance from the longer length.
If i found the batteries became imbalanced, i would then look for solutions to solve the problem. Obvious solutions would be to swap out the existing cables to match the length and size of the new cables. Maybe not an issue at all?
BentleyJ
Solar Wizard
Not sure how the 2 existing batteries are connected at this point. Its highly recommended to use solid copper bus bars and connect all 3 batteries to the bus bar then run a cable to the inverter from the bus bar. Your situation is not ideal, however, DC CIRCUIT resistance is the issue at hand. So as MisterSandals pointed out the recommendation is to make all the cables the same length.
Since that's not an option for your set up (unless you coiled up extra cable for the close batteries) The next best thing would be to over size the longer cable so the "effective" length is approx equal.
Since that's not an option for your set up (unless you coiled up extra cable for the close batteries) The next best thing would be to over size the longer cable so the "effective" length is approx equal.
hwy17
Anti-Solar Enthusiast
I think people suffer from balance anxiety. They want them all close through the whole SOC range and that's very hard to do. If you have one on longer cables and relax about the parallel balance though, they will still top and bottom out together. The top and bottom is where you will get a voltage spread and the laggard will step in to carry at the end.
Don't worry, don't watch, be happy.
Don't worry, don't watch, be happy.
BentleyJ
Solar Wizard
MisterSandals
Participation Medalist
I'm sure you are speaking about me, and its true. But this is one of the few parts of a big system that can be controlled with just a little time, effort and money.
hwy17
Anti-Solar Enthusiast
Lol, not directed at anyone in particular!
I just have a bit of experience with my 304/100 system now that is wired completely lopsided, 4awg and 2/0, and I'm forming a bit of a hardline stance on the topic that equal current sharing doesn't have to matter if you decide the midrange unbalance doesn't bother you.
EG4_Jared
Online Support for EG4 Electronics
I would recommend keeping the battery cables the same length to ensure consistent performance and minimize potential issues. Unequal cable lengths can lead to variations in resistance, which may affect the balance of charge and discharge across the battery bank.
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