Battery cable sizing

[roach711]

No bus yet but my plan is to pick up a Ford E-450 shuttle bus this year. In the mean time I’m busily making plans and scrounging for parts and materials.

Today’s project is to decide on the wire gauge for the battery connecting cables. My assumptions are as follows:

Alternator – 130A (this is the largest I’ve seen listed for the 7.3L Powerstroke engine)

House batteries – (2) 110AH 12v AGM batteries at first with room to expand to 4 if needed. Potentially 440AH total.

Inverter – Minimal inverter use planned but would like the option to add, say 2000 watts later if the spirit moves me.

Solar panels – None planned but not ruling them out, either.

Cable run – Cable length from the battery box under the driver’s seat to where the house batteries will live should be approx. 12’ as the cable runs.

Load center – Progressive Dynamics PD4045 load center with 45A 3-stage battery charger.

So I’m thinking that I need to use #2 copper cable between the isolater in the chassis battery box and the house batteries to handle the 130A alternator output and #2/0 copper cables to interconnect the house batteries to allow for expanding my 2-battery bank to 4 batteries and for future inverter installation.

Have I done my homework correctly or is there something I’m missing?

[roach711]

Smitty - Thanx for the link. Lots of good info there. After looking at several sites I'm leaning toward going with #0 cable between the isolater and the house battery bank but still unsure what size to use for battery to battery cables. I remember that your rig has a pretty hefty battery bank. What size cables did you end up using?

Off topic, what did you use to fasten the FRP panels over your window sheet metal? I'm planning to cover a few side windows and had considered FRP for the job.

[Hex]

Hey, I was wondering about using 'jumper cable' wiring to run to my house batteries from the isolator. Would those work as opposed to going out and getting welding cable?

[roach711]

Originally Posted by Smitty

Sounds like you're sort of "reverse engineering" your electrical system. You need to determine all your loads (including future ones) and size everything accordingly.

Yup, that's exactly what I'm doing. I'm a newbie to 12v electrical and as such know that there is stuff that I'm not aware of that may come back to bite me. Your electrical setup is about as big as I can imagine going so I know I'm safe using those cable sizes.

I've never regretted over-building a project but have often regretted building "good enough."

Hex - There are good jumper cables and not-so-good jumper cables. Premium ones might work if the wire gauge is large enough and the insulation is adequate, but if 'twas me, I'd shell out for the right wire for the job. Your electrical system is not the place to get creative.