Opinion on types of starting batteries

[poconojoe]

Wet cell, AGM....which should I get next Spring?

Replace with same size? (Group 27)

I looked around throughout the forums, but can't find any discussions on the subject.
I thought there would be a sticky for this....maybe there is, but I couldn't find it.

4.3L (2003) Mercruiser.
I have two wet cell group 27 starting batteries with a Perko 1-2-All-Off switch and a Blue Sea ACR. I don't need any deep cycle batteries.

These batteries were in the boat when I bought it 8 seasons ago. Not bad, I think.

Anyway, I think they are well past their service life and yesterday I had to combine them to get a good crank.

I always pull them for the winter and put them on a Noco maintainer in my basement. I believe this has kept them in service longer.

So, do I splurge for AGM, which tend to be pricey or stick with wet cell? Seems like AGM would be advantageous in a boat due to all the bouncing around they are subjected to.

Do I get larger ones or stay with group 27? I do have the room.

What brand batteries do you all prefer?
One of my existing ones is a Mercury battery, the other is some off brand I can't recall.

Are all batteries basically the same, brand wise?
Are they mostly made by only a few manufacturers and others just slap their own stickers on them?

Opinions or links to discussions appreciated.
Joe

 

[roscoe]

There have been as many discussions here about batteries, as there has been about oil.

You can spend $200, or up to $1500 on a couple of batteries, your choice.

Why would you change from what you have?

Why would you need bigger?

A single group 24 will start a 4.3l.

Please pass the

 

[Lou C]

I don't think there is any need for anything bigger than a gp 27 for a 4.3 V6. What I use are Deka Marine dual purpose batteries, they are better at tolerating drains than a starting battery is, and this can be advantageous if you leave your boat in the water like I do and there is a rain storm and water gets past the cover and runs your bilge pump. They cost a bit more but I think they are worth it. A dual purpose will come back from a discharge that might kill a starting battery, useful in a boat.
AGM batteries are a big step up in cost, and you have to make sure your charging system will charge them properly. Yes they discharge slower and they are safer..... I've though of using them but the extra cost (and weight) keep me coming back to the Deka dual purpose gp 27s. I can get 2 gp 27 dual purpose batteries for the cost of one gp 27 AGM. I usually run them 7 years and then replace them.

While you are at it, check your cables, including the ground cables, high resistance/corrosion at any point will reduce battery life. Also don't depend just on the dash gauge check your battery charging volts with the engine running every now and then with digital meter. Should be approx 14.2V.
If you put the boat away with them fully charged and the battery switch OFF, they should be good come spring.

 

[Scott Danforth]

your choice

group 24, group 27 or group 31

Enersys (and all their companies) makes a great battery
Deka makes a good battery
the 6-pack spiral cell ones not so much

 

[dingbat]

Biggest battery that will fit or you can afford

Been there done that with AGM. No way I can justify the price difference given past experiences with them.

I do nothing special, leave batteries in boat for the winter, and get 8-10 years from a set of lead acid deep cycles. Not to mention deep cycles have a much, much higher tolerance for abuse (deep discharge) than a Starting or Dual purpose batteries.

 

[poconojoe]

All good info.
I'm leaning toward just replacing them with the same size and type.
It seems the opinion is that the AGM is not really worth it.
These two batteries lasting at least 8 years that I know of, I think that's a pretty good track record.