Need help fast- Port engine not starting. Which battery do I pull

[friscoboater]

Ok, this is on my Dads 2000 340. His port engine will not crank unless you use the emergency start, and things run fine. So this leads me to believe one of the batteries is shot. Can you tell me which one in the picture handles the cranking?

 

[Wylie_Tunes]

If you have a digital volt meter, I would start with taking some voltage readings on the batteries, then go drom there.

 

[friscoboater]

Volt meter showed 13 volts. The second you hit the starter it goes to zero. Here is an update. Took both batteries to Oreillys to get tested and they are both too dead to test so they are charging them before testing. Could the on board charger be charging the starboard bank and not the port?

 

[Pyrojodge]

Yes, its possible to only have one battery being charged, there should be an inline fuse between charger and battery, I would look there

 

[Wylie_Tunes]

If the batteries show a level as high as 13 volts, but will not spin an engine over, then I would suspect they are done for. Also, if O'reilly's is using an inductance tester, they should not have to charge before testing, like is the case with the old-school heater grid testers.

Yes, you charger could very well not be charger one or the other. also, is the charger designed to charge gel-cell batteries like the Optima? They require a different charging scheme then a traditional wet-cell lead acid. if the charger is not designed to or not set up to charge gel-cells, it can under charge them. Is the charger connected directly to the batteries or a remote post like the switch? Is it a dual bank or single bank charger?

 

[friscoboater]

Ok, we are waiting on the test to come back while we eat lunch. I betting the optima batteries are fine and it will be the charger or just a fuse

 

[friscoboater]

Another update. Oreillys ran a charge test and the both failed and got SUPER hot. So 500 bucks later Dad has new batteries. We will heck the fuse and the setting on the charger too just to make sure.

 

[northern]

How old were the batteries. Wet lead acid on my boat last 4 years before they become weak. At 4 years I feel they are at 50% of their original capacity.

 

[friscoboater]

Not sure. They were optima AGM batteries, and there was not date code on them at all.