What size wire between batteries

[dcwettstein]

Its me again with more questions. I just purchased 4 golf cart batteries (232 Amps @20) What size battery cables do I need between them? I will be hooking two batteries in series to get the 12V and the 2 sets in Parallel to get 464 Amps. I think I have a wonderful system because of all the help I have received from you all. Thanks.

 

[Brazos]

With four 6v batteries connected as you describe I would use 2/0 for interconnecting the batteries. Are you making your own cables? If you are making your own cables it might make it easier to orientate the lug connectors and also cut down on cable congestion on top of the batteries.

 

[Jim.Allison]

Your wire gauge is not determined by your batts, it is determined by the max load and the distance from the batteries the load is. If you are feeding the DC in your rig and not moving the batteries further away than the original batts and no inverters are involved; there is no reason to increase the size of cables you currently have. HOWEVER if you are installing an inverter then you MUST consult the installation manual, where the cable diameter v. length v. load is listed in a chart.

A cable diameter that is too small will increase the resistance and unnecessary heat will be generated, potentially to the point of melting the insulation off the wire and perhaps damaging the post on your batts in addition the power required to run the load will not be delivered to the load. Cables that are too large are just a waste of money and precious weight capacity on your rig.

The upshot is that if you are just adding capacity to your rig, then the existing gage cables are sufficient, if you are adding and appliance such as an inverter then you must consult the installation manual for the distance v. load v. cable gage.

Its me again with more questions. I just purchased 4 golf cart batteries (232 Amps @20) What size battery cables do I need between them? I will be hooking two batteries in series to get the 12V and the 2 sets in Parallel to get 464 Amps. I think I have a wonderful system because of all the help I have received from you all. Thanks.

 

[Brazos]

As Jim related in more detail to your question as to the load demand you might want to consult your Inverters Manual for recommendations. Since you have an Xantrex SW3012 inverter. Here is a link to a manual for your Xantrex Freedom SW 3012. Link
On page 57 is a recommended cable size. Interconnections can sometimes be a size less than the inverter cables. Refer back to Jim's reference to load and distance.
I would always opt for larger cable to allow for system expansion and safety. Those cables get costly and time consuming to replace when changing out.

 

[dcwettstein]

I have all the other wiring done because I experimented with the 12 V battery that came with the unit. All I needed was a recommendation as to the size of the wire between the 4 batteries. I ended up using #2 wire and soldered on the connectors. I think this should work fine. The wire I have from the batteries to the inverter/charger is 4/0 welding cable if I remember correctly.

 

[Jim.Allison]

If you are putting in a Xantrex 3012 you will need 4/0 or AWG #0000 NOT 4 awg, and you cannot run over 10 feet. The cable should be balanced. I used welding cable because of its durable cover, some say the finer internal copper wire is more efficient, but for our systems I don't think it matters, so the welding cable insulation is more durable.

But I understand what you are asking, and I think the answer to that question might be in the solar blogs and not in the Xantrex manual. Personally I would just go with the #0000 because those assemblies are short and the cost savings would not be that great especially if you make them yourself.

I have all the other wiring done because I experimented with the 12 V battery that came with the unit. All I needed was a recommendation as to the size of the wire between the 4 batteries. I ended up using #2 wire and soldered on the connectors. I think this should work fine. The wire I have from the batteries to the inverter/charger is 4/0 welding cable if I remember correctly.

 

[porthole]

If you are going through the trouble to put in 4 big batteries, why not put decent cables on? They are short runs and in the overall expense of what you are doing, 10-12 feet of 2/0 or even 4/0 is minimal. Especially if you you go small now and end up replacing with bigger-better cables.

Welding cable is a great choice for two reasons, the insulation is flexible and the very fine, high strand count is more efficient and allows the cable to be flexible.
Marine grade battery cable is another great choice.

Run big cables from battery to battery and then a short length to bus bars.

 

[brianharrison]

I concurr with Jim, at minimum the interconnects should be as large as the wire to the inverter, and Xantrex does recommend 4/0 for the 3012 (Here is the link again, brazos link was dead) . It is capable of continuous charging at 150 ADC at 12V (1800W) but the real draw from the batteries is inverter mode at 3000W (250A at 12V) but can peak inverter output to 6000W for short bursts (max 5 min) (500A at 12V).

Ultimately your wire size must be matched to your catastrophic Class T fuse rating (you did install one, right?) - I chose to install a 300A Class T fuse, and I used 2/0 marine grade cable and compression fittings with thick wall shrink wrap. I do not use the max inverter capacity of my Xantrex 3000 inverter. I monitor with the Xantrex battery monitor. Link to my install.

Hope this helps.
Brian

 

[Jim.Allison]

The 0000 ga is to limit resistance. My I would try to make my interconnects the same for this same reason. What compounds the interconnects is that it is 6v, not 12v passing through the series interconnects, 6v is more sensitive to resistance than 12v. So those 2 (series) connections would benefit from the 0000. Then the 2 12v interconnects are part of the circuit and my thinking would lead me to believe that anything that is part of the circuit should be 0000.

Remember the batts are part of the entire circuit, when you get the bank built, you will complete the circuit by attaching the positive cable to one end of the bank and the negative to the other end of the bank. Everything in between is part of the circuit.