Battery question

Soreal53

Seaman
Joined
Apr 2, 2012
Messages
58
I have a 1994 volvo penta v6 with two marine batteries (fairly new) on a perko switch. I have noticed that I get a hard start on my boat when it's on just one battery. But when switched to both batteries it cranks right up with no problems. After I shut down and switch to either battery it starts right up as usual. My voltage tach usually stays under 12 when idle and my horn never works. But when I give it gas and am cruising lake my voltage reads between 13-14 volts and my horn is loud and clear. All my connections on battery and perko switch are tight so what could be the problem??
 

UncleWillie

Captain
Joined
Oct 18, 2011
Messages
3,995
You may have a battery that has seen better days or a drain that is killing the battery while stopped.
With a Portable Hand Voltmeter...
Measure the voltage At The Battery with the motor running above idle speed 13.8v or more??? ... Charging system OK!
Then with the motor stopped. 12.6v or more??? ... Battery OK! <---<<< Repeat in a few hours.
Below 12.4v??? ... I see a new battery in your near future.

Repeat the Test again with the Battery Switch in OFF when the engine is stopped, to rule out something draining the battery.
 

poconojoe

Lieutenant Commander
Joined
Sep 10, 2010
Messages
1,966
Just because the battery connections are tight doesn't mean they are clean. I would take apart every connection I could get to and clean and retighten. Not just at the batteries, everyone I could get my hands on.
 
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