Rear battery not charging?

[dylan117]

Ok so, my rear battery doesn't not seem to be taking a charge, I have a duralast battery under the hood, and an XS Power D4700 in the rear. all skyhigh 1/0 wiring. when unhook the charging wire from the rear battery, and put a volt meter on just that wire coming from the front battery, it's reading 14.4-14.5 with the car on. As soon as I connect the charging wire to the rear battery, the meter reads 12.3-12.4 ish with the car on. I think the ground is good because I've never had a problem with it charging before. any ideas what it could be? XS battery is about 6 months old

[zxsonnyxz]

Measuring voltage with no load doesn't reveal bad connections too well, same with measuring ohm on a wire or connection with a dmm.

But with it dropping that much under load indicates most likely a bad connection somewhere.

Step one is to check all your connections to the rear battery, including fuse. Bolts and wires can loosen over time.

Are you getting 14+V up front with the battery connected? What does the battery itself read?

If you find everything to be okey, equipment do go bad from time to time. You could try hooking a charger to the battery, I think most chargers will give a fault light or something if the battery is dead.