What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

90A Alt B-Lead Size

DavePlaneGrips

Well Known Member
I have a 90A alt and have been trying to size the B lead. Just going off the tables in AEC would have me using a 2ga wire but that seems excessive for a 3 or so foot run from the alternator to the firewall.

I see 6ga alt wires on summit rated up to 190A, but of course that's auto. So I'm not sure what the correct choice is here.
 
I have a 90A alt and have been trying to size the B lead. Just going off the tables in AEC would have me using a 2ga wire but that seems excessive for a 3 or so foot run from the alternator to the firewall.

I see 6ga alt wires on summit rated up to 190A, but of course that's auto. So I'm not sure what the correct choice is here.
How much current do you plan to actually use off this alternator? What battery? The EarthX will pull as much power as your alternator will deliver after starting, but that's only for a few seconds. Since it's such a short run, it won't hurt to use some nice fat welding cable - min AWG#4.

Here's what Bluesea has to say about that:

DC_wire_selection_chartlg.jpg
 
Last edited:
Multiple factors contribute to my load requirements, including seat heaters and not running the ALT at its rated capacity. Peak load could be 70A or more depending on what's on. #4 was what I was thinking, enough to order some from B&C, thanks for that graphic though it's helpful.

I'm going with a Shorai, single bat dual alt. The startup current is a concern so I got a 4" pulley thinking it'd recharge at idle/taxi well under the rated output, haven't quantified it though.
 
Last edited:
Back
Top