Shore power 3 stage chargers and AGM's

bria46 · Mar 1, 2011

I have a ProMariner ProSport 20. Works Great. Now is time to replace my 6 year old-two group 27 batteries. .pmariner.com/productFeature.php?ProductNum=42020

Maine Sail · Mar 1, 2011

Chuck Creel said:
The AGM batteries in my boat gave up the ghost on me last week end on a short overnight trip. The 2 house bank batteries were installed Sept 9th 2004.

Is this life common with AGM batteries? I do belive im replacing them with the exact brand and model.. lol.

The boat also has a guest 2 bank charger that stays on and charges while on shore power. I have been told that this extends the life of the battery if a constant battery maintainer or charger is present all the time and i've been told that it kills the batteries.. In this case i belive that it is why they have lasted so long.

Wow,, 7 yrs,,, !! im impressed.

BTW the brand is Orbital AGM's ORBDC-36, Academy handles them.

The charger now will not come on and also has some age so i think i'll just rreplace it also with the PRO 3 bank charger and feel safer.

Happy sailing.

Charles Creel
S/V Jacob's Dream

Chuck,

You got much better than average performance out of your AGM batteries. I know lots of folks who get 3-4 years and sometimes less. This is likely because you were often able to get them back to 100% SOC. This is very important with AGM batteries. They also tend to die quick unannounced deaths when compared to wet cell batts that tend to dies more gradually..

I know many folks who get 7+ years out of basic 6V wet cell batteries for often less than half the price of AGM. You can buy US2200's and many other 6V batts for about $70.00-$90.00 each but you'll need to water them every now and then. I have seen a fair number of Trojan T-105 banks go ten + even on moored boats with no solar or wind..

Keep in mind that the only AGM's that can be equalized are Lifeline. If I were buying AGM it would be Lifeline or Northstar but those are more offensively priced than Lifeline. Sounds like you're a good candidate for AGM but if you decide to go off cruising consider that you might like never see the kind of life you did when you could plug in and get back to 100% frequently.

This is a direct quote from Lifeline tech support.

Justin G. - Lifeline Battery said:
1- Fully charge after each discharge. Estimated life: 6-9 Years.

2- Fully Recharge at least once a week and equalize once a month. Estimated life: 4-6 Years.

3- Only recharge to 85% and equalize once a month. Estimated life: 2-4 years.

4- Only charge to 85% and never equalize. Estimated life: 1 year.

This is what Trojan Battery says of AGM's:

Trojan Battery said:

Generally, gel and AGM batteries have about 20% less capacity, cost about two times more, and have a shorter cycle life than comparable flooded lead acid batteries.

Click to expand

Trojan Battery said:

However, Gel and AGM batteries do not need watering, are safer (no acid spilling out), can be placed in a variety of positions, have a slower self-discharge characteristic, and are more efficient in charging and discharging than flooded batteries (see table below). Gel batteries are more suitable for deep cycling applications whereas AGM batteries are more for light cycling and engine-starting applications.

Click to expand

Steve Dion · Mar 1, 2011

I had WM Gel's on my '85 Hunter 31. I got 10.5 years on them with a Xantrex Statpower 20.

I now have Gel's on my Hunter Vision with a Xantrex XC charger. Starting our 5th year so I am not sure how long we can expect on this set.

I was told that the Gel's have a longer life than the AGM's. This was from the company that sells all of the different battery types. Based on previous experience I will probably continue to use Gel's until something better comes along.

Not having to clean battery terminals & no required maintenance are big pluses for ME!

Maine Sail · Mar 2, 2011

Chuck Creel said:
Wow, Im impressed , and thanks for the input . i kinda like the low / no maintenence idea like Steve. With my memory fading with age i tend to get the ADD/ADDHD syndrone and forger things.. lol

Re: trojans, then 4 of them gives you about 400 AH;s ?

Thats enough i think for coastal cruising. lol

Trojan T-105's = 225Ah so 4 would be 450Ah. The Sam's Club/Johnson Controls 6V GC2 batts are also 225Ah's but only about $72.00-$80.00 depending upon the club.. That's $284.00 to $320.00 for 450 Ah's....

That's $0.63 per Ah!

The Exide Orbital ORB34DC-36 is a 50 Ah rated battery and costs $199.99 each at Amazon.

4 of these batteries costs $799.96 and they yield just 200 Ah's. This is less than HALF the Ah capacity of four 6V batts!!!

To equal just four Sam's Club golf cart batteries you'd need 9 Orbital batteries. 9 X 50 Ah's = 450 Ah's.

So your cost per Ah is 9 X $199.99 = 1799.91 / 450 Ah's = $4.00 per Ah!!!!

Right it's $4.00 per Ah vs. just $0.63...Not to mention the interior real estate you'd need in Orbitals to equal the 6V wets...

SeaRanch · Mar 3, 2011

Well Chuck, it is nice to see that the AGM's that I installed in 2004 have served so well.
Since the H31 batteries are inside the engine compartment, I did not want to use wet cells due to the engine heat. I put WM AGM's in my C387 last year, love them!

BTW the "starting AGM battery" was not a deep cycle, suggest you make it a deep cycle when you change it out. That little Yamnar 2gm did not really need the cranking amps of the AGM battery that I installed as the "starting battery".

Bill

Maine Sail · Mar 3, 2011

SeaRanch said:
Well Chuck, it is nice to see that the AGM's that I installed in 2004 have served so well.
Since the H31 batteries are inside the engine compartment, I did not want to use wet cells due to the engine heat. I put WM AGM's in my C387 last year, love them!

BTW the "starting AGM battery" was not a deep cycle, suggest you make it a deep cycle when you change it out. That little Yamnar 2gm did not really need the cranking amps of the AGM battery that I installed as the "starting battery".

Bill

Bill et al.,

The WM batteries are nothing more than Deka's. If you can find a local Deka dealer you can save a fair amount of money on your batteries.

Also heat is bad for all batteries not just wet cells so moving them out of the engine space can be a very good idea. Here's some info on how temps can affect batteries:

—Ah capacity goes down when batteries are cold

—Ah capacity of batteries goes up when batteries are warm

—Industry standard temp rating is 25C or 77F.

—Every 15F above 77F the battery life is cut by approx 50% (all types)

—At roughly -20F Ah capacity is about 50% of rated

—At 32F Ah capacity is reduced by about 20%

—At roughly 120F Ah capacity is increased by 12%

—At -20F Ah reduced 50% but battery life increases by 60%

—Charge voltages should change with temperature.

—@ -40F voltage can be as high as 16.4V but at 120F voltage should be no more than 13.8V (GEL's require different voltages)

More specifically the optimal charge voltage for your Deka/WM AGM's at greater than 120F, very typical engine room temps, is just 13.6 volts and that's absorption voltage not float. The optimal float voltage at greater than 120F is just 12.8 volts.. This is why it is critical to use a temp compensated charger if your batts are in an engine space. The C-387 IIRC does not have the batts in the engine space..

sailaway78 · Mar 3, 2011

Sams Club

Chuck,
I have four Sams Club 6v golf cart batts. 450ah. A little over 300 bucks, and going strong starting on 4th year.

AbbySedge · Mar 3, 2011

Batteries

Nice N Easy said:
Chuck,
I have four Sams Club 6v golf cart batts. 450ah. A little over 300 bucks, and going strong starting on 4th year.

OH. you must be talking about the ones we got at Sam's.

SeaRanch · Mar 4, 2011

Maine Sail, thanks for the additional info.
My "electronics installer" worked at WM parttime so... he charged me his price so... I got a pretty good deal.

No. the C387 batteries are not in the engine compartment, but they are under the floor right in front of the engine compartment and it does get warm when motoring for an extended time.

Bill

monkeybars · Mar 4, 2011

just a question about 6V, if you have 450ah at 6v are'nt you at 225 ah when you wire them up for 12V or am i missing something here??

Don S/V ILLusion · Mar 4, 2011

ray carlson said:
just a question about 6V, if you have 450ah at 6v are'nt you at 225 ah when you wire them up for 12V or am i missing something here??

When connected in series ( two 6 V batteries), you double the voltage, not current rating.
Two 6V in series produces around 225 amp-hrs at 12V.

When connected in parallel ( four 6 V batteries, two sets in series), you double the current rating, not the voltage producing around 450 amp-hrs.