My buddy has an electrical issue. The situation is: Group 27 battery relative new (load test shows good when tested after charge), Optimax 175, Lowrance HDS 5 (no LSS), Lowrance Elite 7. On the water running live wells. When he goes to start the big motor both sonar units shut-off. Sounds like a low voltage issue to me but the battery load tests good.

Any ideas. Thanks.