Battery Switch Voltage Drop

[Jon4399]

I thought my house bank was dead or dying. My volt meter on the elec. pnl. showed the voltage at 11.6 volts. I equalized the batteries by disconnecting all positive leads except the charger. After six or so hours, I checked the house bank batteries individually. They each read 13.5 volts. When I reconnected the wiring and checked the voltage at the panel it registered only 12.4 volts. Whats up? It seems I am loosing over 1 volt through the selector switch. Has anyone else experienced this?

 

[sirocovzla]

It may be a bad connection, may some rust in a connector...clean all with W40 in the pannel inclusive. Try to used tin cable..! Also note that the voltage tester in the panel works with a small load so should be a dropp..but your batteries should reach approx. 13.8 if fully charged.

 

[JoeWhite]

If you think there is a voltage drop across the switch then using a digital voltmeter measure across the switch contacts. Also remove the Common cable from the switch to make sure some device is not draining the battery and measure the voltage.

 

[caguy]

I ran into the same problem today. When I got to the boat one of the batteries was at 10.0 volts and the other at 11.8. The Beaches and Harbors guy stopped by and told me that my neighbor had a bad cord and was shorting the system. He disconnected him and left him a note. He said the guy had replaced his cord with new one and all is well. After launching I noticed the motor would not turn over and found the batteries were beyond dead. I managed to charge the over the next 4 hours to 12.8, but got a low battery alarm about a half hour later. When I check them they were back down to 11.2 and 12.0 volts. I wonder if leaving the charger on the batteries for a week with out power ruined the batteries.
Any ideas on checking them?

 

[DianaOfBurlington]

In general deep-cycle batteries don't like to be trickle-charged. They really need to run down to the bottom of their usefulness (within 50-60% of their capacity) and be charged promptly and fully next time. Forcing the deep-cycle battery to live within, say, 14.0 and 13.4 volts isn't the idea. Give it a chance to earn its keep-- and it will longer and be healthier over the long run.

This is why 'dual-purpose' batteries are kind of a misnomer; and it's why you should have a starting battery for the engine's starter and a deep-cycle bank for the 'house'.

 

[sirocovzla]

Yes, I had the same configuration...One sarting battery for engine and four (4) AGM deep cycle for my house bank...then noted that the battery did not charge properly, only 12.7 vl so I bought a new battery and begger charger (50 amp) and replace my old one (20 amp) and now the batteries are fine with 13.9 volts all the time

 

[sirocovzla]

By the way who is sailing to the caribean this summer..?