Low voltage mistaken alarm

[boaterdude1]

35' Trawler, 1990, Low voltage alarm goes off when use the bow thruster, windless, or even after just disconnecting the shore power. Alarm silences after boat is run for a short while. After little use of bow thruster the helm gauge reads 11.2 volts the lower helm also reads low at 11.2. Test the batteries with multi meter and get 12.6. Batteries are fine. How can I locate the problem? guessing it is a loose or degraded wire somewhere. How best to track it down.

[tkeithlu]

Two simple routes.

In the first assume that the batteries are indeed fine, and sand corrosion off every connection between the batteries and your heavy current users, such as starters and winches. Consider coating the connections with conductive grease or corrosion protection. Don't assume that the presence of an OK voltage means that the wires can handle the current that you need.

In the second, charge and test the batteries. There are lots of very sophisticated and expensive ways of doing that, but a simple resistance load/voltage automotive battery tester from Walmart (even cheaper at Harbor Freight) will tell you that a battery is not holding a charge.

https://www.walmart.com/ip/Battery-T...ster/401358401

Good luck with it. It should not be a difficult problem to solve.