I was a bit afraid I'd knock my jar off and break it as I was working on Big Blue today. So I disconnected both positive battery cables to do the work. Jar is still full.
As for what battery cables I have, I made both positive cables but the negative cables are factory because they are in good shape. However, when the time comes to replace them I'll make new ones.
In fact, I may go ahead and make a new negative cable for the auxiliary battery as the factory one grounds to the driver's fender. So if I press the button to parallel the batteries when starting the ground path for that battery will be from the driver's fender to the radiator support to the passenger's fender to the negative battery post on the main battery. But none of my ground wires that connect those chunks of sheet metal are sized to handle starting currents.
So, what I really ought to do now while I'm working on the electrical system is to make a new ground cable that goes to the block. And if anyone on here is interested I could put together how I make that negative cable. Thoughts?
Gary, AKA "Gary fellow":
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Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI