Battery change

[charlg]

I need to buy 2 starting batteries, and based on the battery threads it seems like AGM is the way to go. I know I'll have to change all three (2 starting and 1 house). We do not overnight, just use the radio and sometimes turn the fridge on while we are out for the day.

Is it OK to go from a 27 group deep cycle to a 34 group AGM?

 

[hack4alivin]

I have AGMs and I love them but to be honest here I think you are wasting your money on them. If you don’t anchor out and use a lot of house power than the AGM batteries are overkill for you. You can buy at least 3 regular batteries for your boat for the price of one AGM.

 

[charlg]

I can get the AGMs for only $119, but, they are 34 group. Will that size be ok to use?

 

[Mike Blake]

Only 119.00 ? what kind? I just got 3 31's at 200 each. Optimas

 

[charlg]

These are Optimas. The 31's are $179 and the 34's are $119. I just want to make sure the 34's are the correct size.

 

[EmrldDvr]

Ok, I just spent several days researching batteries for my "new to me" 450. When I went to galveston to prepare it for shipping all four batts were dead. I chrged for 2 days. Bateries held god charge w played in the ICW a couple of days then loaded to head for Lake Ouchita, AR. When we got ready to splash it guess what, no power in batts. I assumed they were caput. So here went the daily search for info. The main thing that I learned was that you almost definetely can NOT trust most manufactures to publish ratings that you can compare apples to apples. The number one internet rated AGM (besides Rolls or maybe a couple other really expensive manufactures) seemed to be, of all things, a sears Die-Hard Platinum Marine. Best price I found was 239.00 with 36 month warranty. Btw don't get to caught up in the warranties. With that said, the AGM or absorbed glass mat batteries are exceptional batteries but I could not find any real benefit to most of us boat owners except the fact that we don't have to check water levels. Sure you can mount them upside down on there side or any other way you want to. When comparing the apples to apples ratings they appeared, to me (and I do not claim to be, represent myself to be or in any other manner am an expert, I've just read as much as I could stand) to be inferior to plane old wet/flooded cell batteries. Now deep cycle vs. starting, as we all no deep cycle batteries have much thicker plates sometimes up to .270" thick and consequently can be depleted completely and recharges sometimes in excess of 500 cycles. But the thicker plates with less surface area as compared to starting batteries do provide the initial cranking amps or umph to crank for long periods of time. They discharge quickly at high amp draw. Starting batteries on the other hand due to there very thin plates provide a greater amount of initial cranking amps but will not stand to be completely depleted vary many times, maybe just a couple dozen and they are gone. Contrary to what I always believed, that a deep cycle battery would be destroyed if used as a continuous duty or starting battery, does not seem to be true. With all the information I absorbed (or maybe not) I decided to to put mutliple deep cycles in parallel. With a deep cycle cranking amp of say 850ca which would be small for most larger starting type batteries we double that. Now 1700ca and you have the ability to deplete them multiple times, although you should never deplete both battery banks, without destroying them (think refers on converters or large high energy stereos. Just some thoughts, and my conclusions could be incorrect. btw meant to add Optimas, although very fine batteries, were one of the pioneers in AGM technology for auto/boat applications. In thier beginnings they were the very best available. Now there are many alternatives that seem to be less expensive andd offer higher ratings, imho. Also that Die-Hard I mentioned is a rebranded Odyssey almost $200. cheaper http://www.ifish.net/board/archive/index.php/t-383168.html.