12v wire thickness

timelinex wrote:
I have a 2kw inverter and will be getting a 100a converter for my 2 100ah lifepo4 batteries. Currently I'm just using whatever ga wires came with everything (a bix of 4/6/8).

I am planning on changing everything to connect through a BUS BAR and upgrade all the cabling to heavier ga. I want to future proof it to handle a 3kw inverter.

It's been REALLY confusing figuring out what wires I need. ALMOST everything online "(forums and articles) tell me I need something like a 4/0 guage, which is HUGE. That makes sense considering 3kw can reach 200-250 amps. Except the fact that no OEM items come with something nearly this thick.

I think the reason all these recommendations may be wrong is they do not account for length of wire being very short in our use cases.


It looks like considering everything is definitely under 4ft, I won't need anything over 4ga. On the other hand, I'm pretty sure that ampacity is over max 4ga rating when you look it up.

Can anyone make any recommendations based on actual knowledge and not just heresay or making best guesses?

Look at the cables/connectors from your chassis battery to the starter motor. What size/material/insulation are they? It's quite normal for your starter motor to draw well over 250 amps @ 12 volts (nominal) to start the vehicle. Granted, it's usually for only a short time, but when you need it, . . . . you need it. It's not just the size of the wire, the connectors are important too, since over time, often (not always) they initiate the failure of the wire.


Chum lee