The Endless Enigma: AGM vs Std and Deep Cycle vs. Cranking vs. Dual Purpose in a single battery environment...

[Roccus7]

Learned Colleagues:

My Exide Dual Purpose AGM battery is going through death throes and I'm debating on what to replace it with. My power demands are minimal, as I'm starting a 115 HP 4 cycle Yammie (Even have an emergency pull cord, LOL), and running minor electronics, Garman GPS/Sounder/Radar & a VHF. Radar is on a separate switch so I have it OFF 99.9% of the time and I'm always underway when it's being used. And yes, as it's a single battery I do carry a fully-charged jumpstart pack aboard so I don't have to actually try using the pull cord.

I've had good success with the Exides; this is my second battery and the boat is over 13 seasons old, so replacing it doesn't bother me, but should I start considering alternatives?

Questions:

1. Should I continue with Dual Purpose or go to Deep Cycle? I'm thinking Cranking isn't a big factor since the engine isn't a monster or am I being stupid?
   
   
2. Should I continue to go with AGMs or not worry about that? Having a tough time finding AGM DPs in stock at size 24...

Your excellent advice on this matter is most welcome...

 

[BoatGuy]

Just as an FYI….MY 125 Mercury would not start as the gear in the starter would not engage the flywheel. I saw the cord and felt I had nothing to lose. It started on the first pull. Mind you the engine was already warm. I doubt I could have started the cold engine that way.

Back to batteries…..My first two batteries were standard marine dual purpose batteries. I never had a brand name, and they were “OK”. I can’t say they left me stranded. All I leave on when drifting is my Garmin and the ICON.

Last replacement I went with an Odyssey 34M-PC1500ST TROLLING Thunder Marine Dual Purpose Battery. I have heard good things about AGM batteries. It seems to have more guts and never seems to run low. The only reason I would hesitate to replace with the same is price. They have gone up in price, at one time over $400. But I'll add, when I went to Captain Jeff for some electrical work, he commented I had a "top of the line battery". He knows his stuff.

I might consider a top on the line NAPA battery as they seem to work good in the cars. I would avoid the OPTIMA batteries. Never had good luck with them. If they drain, they do not recover well.

My 2 cents for the day.