Time to replace the battery... opinions?

[trainwreck71]

Just bought a 76 Chrysler Sport Satellite. The battery in it is a 5yr old maintenance free starter & deep cycle battery. I charged it and after tested the voltage and it was 12.9V. My question is how do you know if the battery is going to leave you stranded? If I replace it should I get a Starter only batter? The Chrysler manual states to use a battery that has 70Ah. I noticed that starter batteries have a MCA rating mostly and that the deep cycle batteries are rated in Amp Hours and reserve capacity in minutes. There isn't alot of electronics on the boat to operate besides starting it. Only the Nav lights and the trim/tilt, which I think are operated by the battery. Opinions appreciated.
(I also have onboard a deep cycle battery rated at 100Amp hours for my trolling motor & possible a fish finder)

Thanks,
A newbie
Trainwreck

 

[DRIFTER_016]

Re: Time to replace the battery... opinions?

Purchase a Marine Starting Battery.
If you have a stereo or other electronics you want to use while the engine is not running purchase a Marine Starting/Deep Cycle Battery.
Look for MCA of 600 or better and you will be fine.

You can take your current battery into Napa and have them load test it for you. This will tell you how your batteries health is.
Just make sure it is fully charged before you do to get accurate results.
I gather your 12.9 volts is with the engine off? If so it should be fully charged.
The load test will let you know how much reserve power the battery is good for. If it fails the load test or ends up in the warning area replace it if it is in the green go boating.

 

[JB]

Re: Time to replace the battery... opinions?

I don't see any reason to replace that battery.

If you don't trust it take it to a shop and get it load tested.