Voltmeter displays low voltage - but battery is good???

[ntheyer]

I have just load tested my battery, and it checks out perfectly. 12.8 volts and 11 volts under load. The issue is that even when the battery is currently on the automatic charger and I turn the ignition on for a second, the voltmeter still only shows around 10.8 volts.? This was working fine before. I had a CD player installed a few months ago, but it was working fine for about two months after the install.

If I run the engine and get the RPMs up somewhat, The voltage does then indicate around 13.2 or so volts.

The problem is not the gauge itself because if I am just floating with the engine and ignition off, the CD player will cut out due to low voltage, so it's not my imagination...

If I run the trim for example, the voltage just drops completely and instantly to around 9.5 when I click it. It really all seems to mean that my battery is dead. The battery is definitely good and starts the boat as if it were so. The battery connections are good.

I have a Merc 470 without the alternator refit. Does this mean the voltage regulator is getting weak?

I don't want a bad surprise on the middle of the water one day with a dead battery!

- Low voltage on gauge with engine at low RPM
- Low voltage on gauge with engine off
- Voltage is good when at cruising speed.
- Voltage drops drastically and suddenly when adding load i.e. running trim pump.

Thanks for your help.

 

[tommays]

Re: Voltmeter displays low voltage - but battery is good???

you need a real DMV to test things the guage is just a bit better than and idoit light mine has always read 1 volt low

The trimp pump pulls a killer load OVER 100 amps when its in good condition WITH good cables and connections


So i would be sanding and cleaning those cable connections OR if there orginal think about NEW ones


tommays