Re: [Amel Yacht Owners] Re: Engine and Service Battery circuits Isolated

Alan Leslie

Hi Jean Pierre,

I had AGM batteries in my last boat. They were 5 years old when I sold the boat and in top condition.  We had a large alternator on the engine with a 3 stage regulator plus solar panels with an MPPT controller, and this system kept the batteries in good condition.

Our Amel has a 175Amp alternator on the engine that has an automotive regulator in it produces 28.8 V all the time its running.

This is no good for any deep cycle battery, AGM or flooded...this I believe has been the nail in the coffin for my current lead calcium batteries....long hours of motoring with the voltage staying at 28.8

Deep cycle batteries need a bulk stage (max current until voltage rises to a preset value e.g. 28.8V), and absorption phase (constant voltage e.g. 28.8V until the current drops to a value of around 5% of total Ah capacity) then a float stage (constant voltage e.g. 26V)...this is what the dolphin chargers run from your genset do.

I'm replacing the 12 x 12V batteries with 12 x 6v AGM batteries wired 4 in series and then 3 banks in parallel.

I'm taking the automotive reg out of the 175A alternator and setting up a Next Step 3 stage reg...

And I'm putting up an arch (ala Bebe) on the stern to carry 3 x 190W solar panels wired in parallel and with an MPPT controller.

This setup will keep my new AGM batteries in good condition, as they were on my last boat, I am sure.

SV Elyse SM437 ...still on the hard at Gulf Harbour - weather !!

---In amelyachtowners@..., <jgermain@...> wrote :

Hello Alan and Richard,

I had GLASS batteries in my last boat.  They require some very specific handling.  I will use lead/acid in any cruising vessel I purchase.


On 24 Apr 2014, at 14:37, Richard03801 <richard03801@...> wrote:


Hi if you change to glass batteries that are no maintenance you also need to change the charging pattern of your charging system that's the downside. The second downside is depending on where you cruise glass batteries may not be available should you need a replacement. Under no circumstances can you mix and match AGM batteries and Lead acid. 
Camil has designed a pretty good system you might want to stick with it for a while and just leave it be. 

Richard Piller

Cell 603 767 5330

On Apr 24, 2014, at 7:12, <divanz620@...> wrote:


Personally I wouldn't worry too much about the start battery, I don't.

The main engine has a dedicated alternator to charge the start every time you run the engine the start battery is charged...just like your you have a monitor for that ?....I'm guessing  the answer is no...

Same with the genset...there's a dedicated alternator that charges the start battery (same battery as the engine charges)

So in total...don't worry about it...just keep it topped up with distilled water.....or better, do what I'm gong to do and replace it with a no-maintenance AGM battery



SV Elyse SM437

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