Battery cable size, need help with please.

[sjturbo]

I am putting together four series/parallel GC batteries and need some help with cable sizing. Batteries are all side by side, converter will be within 3'of batteries, inverter should be within 4', but the DC fuse board is 15' to 17' away. Am I correct that all "series" lengths need to be the same. And the same for the parallel lengths? And the lengths from the batteries to the converter and inverter?

[mena661]

smkettner wrote:
Otherwise look for odd piece or used on ebay.

True, you could get used on ebay. They usually don't have lugs though. You'd have to crimp your own.

[RJsfishin]

Welding wire is for flexability, for being portable. There is absolutely no reason for using that expensive stuff on a stationary run. Buy the HD stuff they use in houses,...even the OEM uses it.
And no, batt cables don't have to be the same length. You are not building pianos, or tuned headers.

[time2roll]

I think you need about 25' #6 and 25' #4 so $78 for the wire complete. Then get your lugs etc and you should be under $150 for the whole set up.

Otherwise look for odd piece or used on ebay.

[sjturbo]

Yes you are mena661, no doubt about it! Now that I've established 4ga is acceptable in my case can anyone suggest a less expensive alternative than battery or welding wire? I guess I did not think this through completely but having to spend $100 just on the run from the converter to the DC distribution....well I guess I was hoping for a fair bit less?

[mena661]

sjturbo wrote:
Thanks for the clarification. If I were to upgrade in the future to a 1500 watt would I just increase the gauge to the inverter? I've seen some very large cables on the forums.

I'm a big wire, less than 1% voltage drop kind of guy. My interconnects are 2/0, 300W inverter wire is #4 and my main "bus" wire is 4/0 (soon to be downsized to 3/0). But that's not always necessary for others.

[time2roll]

1500w is going to be 1 or 1/0 IMO. The #4 interconnects remain OK but all must be in place to share the load.

BTW I would go all in with 2000w if you get that far. And upgrade all wire as needed. Direct connection to the converter and main panel would not change.

I use this ampacity chart:

http://www.genuinedealz.com/voltage-drop-calculator

[2oldman]

sjturbo wrote:
If I were to upgrade in the future to a 1500 watt would I just increase the gauge to the inverter? I've seen some very large cables on the forums.

Yes. Simply calculate the amperage draw, then find a cable sized to fit.

[sjturbo]

Thanks for the clarification. If I were to upgrade in the future to a 1500 watt would I just increase the gauge to the inverter? I've seen some very large cables on the forums.

[mena661]

2oldman wrote:
You don't need the interconnects so big. The biggest wire is usually the run from battery to inverter, but your inverter @ 600w will only draw around 50a full bore. 4ga is good to 70 or so.

Yeah, you don't need 2/0 on the interconnects. I'd just go #4 all around.

[time2roll]

sjturbo wrote:
Thanks for responding. MEXICOWANDER, So I would be good to go with: 2/0 from batt to batt, 4ga from batt to converter, 4ga from batt to inverter..snip

I think MEX was referring to the #4 only. Actually the interconnects (batt/batt) can be smaller but #4 is not that hard to work with and all same size makes the logistics easier.

[2oldman]

You don't need the interconnects so big. The biggest wire is usually the run from battery to inverter, but your inverter @ 600w will only draw around 50a full bore. 4ga is good to 70 or so.

[sjturbo]

Thanks for responding. MEXICOWANDER, So I would be good to go with: 2/0 from batt to batt, 4ga from batt to converter, 4ga from batt to inverter and 6ga to DC distribution 20'?

[Ron3rd]

sjturbo wrote:
Thanks for the replies. The converter is a PD9270 and the inverter (not purchased yet), will likely be a 600 watt pure sine wave. The manual only indicates that the output terminals are rated for 2 to 14ga copper wire. They likely don't recommend a specific gauge for liability reasons.

I bought a Samlex inverter and the manual had the wire sizes for the various run lengths. Download a Samlex manual for a 600 and see what it says. You can find it at bestconveter.com

[beemerphile1]

4 gauge should work for the converter and inverter and is easy to get. I have found that anything heavier than 4 is harder to find locally.

The equal length concept is not extremely important for your situation.