Battery Cabling

[edroelle]

I need some guidance.

I am rewiring my house battery bank of 6 batteries and 2 inverter/chargers.

Xantrex recommends Option A in the attachment.  However, I do not like the failure mode of only 1 path for the electricity to follow.  A high resistance of one crimp alters the system as designed.

Option B just adds 2 cables to form a loop such that charging or inverting can take 1 of 2 paths.

Option C is wired so each inverter/charger connects to 3 batteries, but is also cabled in a "loop".

What do you think?

Thanks,
Ed Roelle
Flint, MI

[edroelle]

Color attachment may be easier to follow.

[gumpy]

I would probably approach it a bit differently, and connect each lower battery in your drawing to the upper one above it, resulting in three sets of 2 batteries in parallel. Then connect the three sets in parallel as shown in the upper set of the three diagrams, and feed your inverter positives off one end, and negative off the other end.

Hard to describe. I think you end up with the same number of cables, though. 

By the way, Waytek sells a stud you can bolt to your wall to combine multible cables like you show on your positive cables. Work very well. They also make one you can use to pass through a bulkhead.

craig

[Sean]

Ed,

I favor Option A.  Your concern is valid -- so make certain that your crimps are good!

Option B will guarantee that you will draw (and replace) more energy from the two batteries on the left that the two on the right, resulting in differential "aging" of the batteries.  Generally considered bad practice.

Option C will mean you basically have two separate inverter/charger/battery systems.  If that's what you intended, great.  But it does mean that, for example, a failure of one inverter will mean three of your six batteries can not be used at all.

There is a fourth option you did not mention.  That is to wire each and every battery to a positive and negative stud (with identically-sized cables), then each inverter to those same two studs (again with identically sized cables).  Now you still have all six in parallel, and, if all connections are good, you will empty and refill all batteries equally.  if one battery has a bad cable or crimp, it will, of course, supply less power and get less charge, but the other five will still participate equally.  Also, you can remove, add, or replace batteries at will with this setup without having to turn off the system or affecting the other batteries. This option requires more and/or longer cables, though, and some pretty beefy studs.

FWIW.

-Sean
http://ourodyssey.blogspot.com

[Len Silva]

Ed,

I was just about to suggest the same as Sean's fourth option with individual cables from each battery to a common tie.  Another advantage to this setup is that you can use smaller cables as each will only be carrying the load of one battery.
With your string setup, the jumpers should (theoretically) be the same size as the main cables to the inverter.

Len

[Cary and Don]

We have to agree with plan four.  We have a loop on ten golf cart batteries now.  The first and last battery on that require continual cleaning on the terminals.  The others never do.  That pretty much says they are taking all the work.  Our next set up will have each battery going to a bar and have a disconnect on each battery. May be more cables but it should be a lot better in the long run.

Don and Cary
GMC4107

[Jerry Liebler]

I favor a modified version of option a.  The modification is connect one inverter/charger as shown and the other connects to the oposite polarity of the same battery so the - input for inverter 2 comes from the - terminal  of the battery that is supplying the + input of inverter 1 and the + input of inverter 2 comes from the + terminal of the battery that is supplying the - side of inverter 1.  The advantage is  that there are only 2 lugs per battery and there is a bit of independence between inverter 1 and 2.  For each inverter it still will gives equal wire length to each battery if 'coresponding' wires are equal length and guage. 
Regards
Jerry 4107 1120

[edroelle]

Thanks for the excellent ideas.

Now I need to go out to the barn and incorporate them.

Thanks,
Ed Roelle