Help with dual battery setup and low voltage prob

Just added blue sea systems "add a battery 7650"

When the engine is running it shows 13.8-14volts on the dash gauge but only 10.5 on the cap digital readout. If I move the battery switch to combine it reads 13.8 volts on the cap. See my wire diagram below. The boat runs fine but the stereo is cutting out due to insufficient amount of power. Any suggestions? All wires are 2/0 gauge except the stock 8ga wire on the alternator to the starting post on the motor. Is this a potential bottleneck?


(Message edited by showtz on June 02, 2008)

blue sea diagram

One possibility is that your accessory battery has a dead cell or is almost dead. Another is that you have corrosion in the switch on the post from your accessory battery. Check for resistance levels across the switch and load test the accessory battery.
Then check for corrosion on the cable ends that are associated with the accessory battery.

Found the problem....forgot to ground the ACR (Auto charging relay)