Originally Posted By: weebl
Thank you, I will test the diodes using the multimeter in AC mode.
Some interesting observations when I got home last night and looked at the vehicle:
Battery charger was showing that it was maintaining the battery. The vehicle started just fine on the first try.
Ran voltage tests, vehicle running, not running, all voltages seem to be reading normally. After a drive to do a quick errand (the vehicle did not need help restarting), and returning home, I tested the battery after giving it a chance to rest, to determine the charge level (vehicle off, no charger connected): 12.73 volts exactly.
I disconnected the positive cable, and used the multimeter to measure if there was any sort of parasitic load. After keeping the leads connected for a few minutes, the vehicle went to sleep, and the readings fluctuated between 0.00 amps to 0.01 amps. So that seems normal.
I did notice where the insulation on the positive battery cable peeled back a bit, that there was some very mild evidence of oxidation. Nothing heavy, but possibly something inside the cable?
Reconnecting the positive cable, I restarted the vehicle. Except it didn't start, it went through the cranking, then fizzled out mid-crank. Going back to the battery and checking the charge still showed it was good.
Tried restarting again after checking that the cable was indeed tightly on (even snugged it up a bit), not really sure if that did anything or not, and this time, it cranked fine and started.
If the diode test checks out, then my feeling is I need to replace the battery cables, if they are showing signs of oxidation. They are not entirely OEM, the leads near the battery were replaced and spliced far from where that first Walmart battery badly corroded the OEM cable. I had found where the corrosion ended, then went several more inches to ensure the splice was where it was clean copper. This time around, I will do the entire length of cable (unless I find the diodes are the issue, and go down that path).
Get rid of the splice. Replace that whole cable. A splice acts like a resistor unless it is formed perfectly. Far simpler to replace that positive cable with a quality all-copper cable. Don't cheap out. Get at least the gauge of cable that's already there and don't use copper clad aluminum cable.