Agm batteries

Joe arrigo

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Look to use odyssey agm batteries anyone have info. I’m using them on my 96 2 stroke Yamahas
 

Hookup1

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I'm using all Duracell AGM's purchased at Sam's Club.

Group 34 43.10 lbs. 955 MCA 55 AH. $119.32
Group 24 52.40 lbs. 800 MCA 78 AH. Did not see availability at my store.
Group 27 61.55 lbs. 900 MCA 92 AH. $158.88
Group 31 67.35 lbs. 1,000 MCA 105 AH. $179.74

I used a Group 34M Duracell Marine AGM for my Yamaha F150's. About 9 lbs lighter than a Group 24 and 17 lbs lighter than a Group 27 with higher MCA rating but less capacity. Also used for my 4th battery for bow thruster, windlass and bait tank pumps.

For the house I use a single Group 27 AGM. You could parallel two new ones. Or do a Group 31.

Both engines wired with charging shunts. One connected to house the other to the 4th battery. When underway all 4 batteries are charging.
 

Doc Stressor

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Just something to keep in mind: For a long time Yamaha specifically warned against using AGM batteries. This applied to their older engines. Their alternators were not designed to operate at maximum amperage for long periods of time. The concern was that they could overheat while charging depleted AGM batteries. AGMs have considerably lower internal impedance than flooded cell batteries and allow for a much higher charging current flow. Newer engines have redesigned alternators that are cooled in various ways to allow for longer term operation at high output.

I had a 2004 F150 that said not to use AGMs. So I asked Yamaha about their warning. I used AGMs anyway without a problem, but I never let the batteries discharge much.

Oddyssey batteries are expensive but have a very good reputation in boats and RVs.