es127 shuts down

[Captainpete12]

When under sail for a few hours my new es127 shuts itself down. I can turn it back on, but after several minutes it does it again. After doing some research and talking with a Raymarine tech it appears to be a voltage problem. I thought if I shut off my freezer/refrigerator while under sail (no motor charging the batteries) it would reduce the draw on the batteries. That did seem to work however, if I am using the auto-pilot the same thing happens (auto pilot draws from the batteries as well). While at the dock with shore power on and batteries charging, the es127 will run forever - therefor it must be the batteries. I am starting to think perhaps I should replace my house batteries with ones with greater amperage? These house batteries were new last year. They are wet cells and will charge up to 13.7 volts. I hate to do it but, if necessary, get new batteries again. I would like to rely on my MFD while under sail but, that does not seem possible at this point.. As usual, any help would be greatly appreciated.

Capt. Pete