Battery Charger and Wire Guage

[wjcons]

I recently bought a new battery charger. Even though the specs called for
12 guage, I installed oversized 10 AWG wire to the AGM batteries (one
battery on each of 2 banks) when I installed the charger. When I crimped
the fuses into the cables at the + battery terminals, all I had was 12 guage
butt splices, so I just trimmed off a few strands from the 10 guage wire
right at the splice. Once I had everything hooked up, I saw that the
charger would only charge my batteries to about 80%. Well, I finally got
around to replacing the butt splices with 10 guage, and now the charger is
charging my batteries to 100%. I don't understand how less than one inch of
12 guage wire, or the 12 guage butt splice could have introduced enough
voltage drop to cause an 80% charge in the batteries. Am I missing
something?

TIA for any responses.

 

[wjcons]

The problem was definitely not the one inch of #12 per se, but it could
have been due to a bad crimp or some other cause. As the battery
approaches full charge, the current through the wires decreases. For a
battery near full-charge, #18 wire would probably work fine.

Yes, it must have been a bad crimp. I always give any wire connections I
make a healthy tug to make sure they are tight, but I guess you never know.
Thanks for your input.