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Author Topic: Electrical Systems 101  (Read 60613 times)

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Stu Jackson

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Re: Electrical Systems 101
« Reply #30 on: February 04, 2016, 01:18:09 PM »

Additional Observations on AGM Batteries  (from ---

Topic:  Battery advice, please?

Summary:  This supports much of what Maine Sail has written about the choices we have to make about battery types.

Copy of text from CF for those of you who don't like clicking on links:

I have an AGM bank and I recommend against them for cruising.

I have AGM due to sizing constraints of the battery box, but they require being fully recharged at a min of a couple of times a week. And if yours allow it, equalizing monthly.
Great batteries for what I do now which is weekend cruise and a vacation once in awhile, but the rest of the time tied to a dock with shore power.

My opinion is if you have AGM, you need significant Solar, and my plan is to run the genny a couple times a week early in the morning to get through bulk phase and deep into absorption with the idea that when there is enough Sun, Solar can top them off.

Even in the tropics, even with unlimited Solar, due to acceptance rate, you can't get to 100% charge on Solar alone, just not enough time.

With no Solar, a couple of times a week the generator needs to run all day.

I believe 10 years is pretty uncommon for a bank, even if you do everything right, I believe 5 is closer to average.

With out going with significant Solar, and a big ole charger, it may make more sense to do what you have to to put in golf cart batteries with the idea of replacing them every few years as you'll likely be cycling them between 50% and 85%.

AGM are high $ batteries and will not last if you cycle them at partial charge more than a year or two.
« Last Edit: August 17, 2018, 01:02:52 PM by Stu Jackson »
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."
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