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Old 01-10-2014, 10:18   #16
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Re: AGM or Gel?

Originally Posted by ranger42c View Post
MS, does anyone make 6V valve-regulated gel deep cycle "golf cart" batteries?

I haven't been able to find that option in various 'net searches...


The only gel golf carts that I know about are Gel Tech and Sonnenschein.

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Old 01-10-2014, 10:24   #17
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Re: AGM or Gel?

Originally Posted by savoir View Post
The only gel golf carts that I know about are Gel Tech and Sonnenschein.
Gel Tech is yet another East Penn brand.

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Old 01-10-2014, 10:34   #18
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Re: AGM or Gel?

[QUOTE=Maine Sail;1642582]Really? You got sources for that myth..?

AGM's are just as tough to use and set up properly.

GEL's are very easy to use they just need proper charging. When you do this the average life of a GEL battery will almost always exceed that of AGM. In the real world I have yet to see a properly charged AGM battery bank out last a properly charged GEL battery bank... The key word for both is "properly charged"...

All one has to do is take one look at a manufacturer who makes both types of batteries and their own cycle life ratings for their own batteries.

BTW the Rolls AGM's were/are made in China to Rolls specifications. There has been talk of building them in Canada but I don't know if that has happened yet. I don't see enough of them to form an any opinion on longevity...

I can only offer my real world experience across many hundreds of vessels. You certainly can maximize the cycle life of AGM batteries but it can get expensive to do it right. I still install a LOT of AGM batteries but they are always installed and addressed as a compete system not just a drop in replacement for flooded batteries. The fact that Lifeline AGM's can be equalized makes them a clear winner for me in the AGM market but Odyssey is a close second.

John Harries has written extensively about AGM's and it is a must read for anyone considering AGM:

Morgan's Cloud AGM's

Perhaps the best way to see how a battery should perform is to look at a manufacturer who makes all types. For the Deka/East Penn brand this is how they rate their own batteries.

NOTE: Only ratings within a brand/manufacturer are useful. Cross brand cycle life data is useless because there is no industry standard for testing. Much of the cycle life data from manufacturers is Disney fairy tale stuff.. Most all of them are fantasy level data when applied to real world marine use. Only in-house manufacturer testing across their own batteries can be compared for guidelines.

East Penn:
-GEL Cycles to 50% = *1000 Cycles
-6V Flooded Golf Cart - Cycles to 50% = *700-1000 Cycles
-12V Flooded 4D, 8D, 24, 27, 31 - Cycled to 50% = *350 Cycles
-AGM Cycled to 50% = *300 Cycles

*NOTE: These are usually not what you will see in the "real world".. Deka rates their batteries more conservatively/honestly than most..

That is not my data but Deka's own data across their own batteries.... As can clearly be seen;

*They rate their 12V DC wets at 50 more cycles than AGM. (not a true deep cycle)
*They rate their 6V DC wets at 400 - 700 more cycles than AGM
*They rate GEL at 700 more cycles than AGM...

The problem with GEL batteries was the folks who marketed them not the batteries themselves. GEL was having a hard time gaining foot hold due to the lower charging voltages (14.1V) so they began telling everyone it was okay to charge them with flooded equipment. BIG MISTAKE! It gave GELS a black eye and allowed the AGM makers to gain a stronger foot hold. They then began a misleading marketing campaign about depth of discharge (recommended 80% DOD to justify cost now they recommend 50% max DOD) suggested a lack of sulfation etc., etc... They too gave themselves a black eye and had to adjust much of the early marketing...

If I was choosing a cruising bank of valve regulated lead acid batteries for my own vessel hands down it would be GEL over AGM.....

I have numerous GEL banks on cruising boats beyond 11 years and one at 15....[/QUOTE

Your right on Main Sails. You want to know about batteries go to Morgans Cloud and you will find all you need to know about batteries. Gels are the only way to go. Some might argue that lead acid are easier to use but you need good ventilation.
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Old 01-10-2014, 11:19   #19
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Re: AGM or Gel?

Originally Posted by jcapo View Post
Gel Tech is yet another East Penn brand.
Most of the GEL batteries you find in the US these days are an East Penn product. The MK is an East Penn as is GelTech. Heck even NAPA rebrands the East Penn GEL battery as does West Marine.

The Sonnenschein Dryfit Prevailer batteries are also good and Sonnenschein is now owned by Exide. They are harder to get/find in the US and usually more expensive.

The Deka product is much more widely distributed and a GC2 6V is very easy to find in a Deka/East Penn GEL.


Early Deka GEL batteries were labeled as Prevailer Dryfit because Sonnenschein licensed their GEL technology to East Penn and taught East Penn how to make GEL batteries. It is pretty expensive to ship lead over seas so this licensing agreement was formed.

After Exide bought Sonnenschein Deka/East Penn could no longer use the Prevailer label and that label/brand went back to Exide. The Deka/East Penn GEL batteries are still built using the original German Sonnenschein technology though..
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Old 01-10-2014, 12:32   #20
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Re: AGM or Gel?

Ah. Thanks, guys. That helped me do a much better search!

I see Trojan has 6V-GEL batteries rated at 189-Ah (20-hour rate) and Deka has 8GGC2 6V gel batteries at 180-Ah (ditto 20-hour rate).

I had earlier been looking at Lifeline's GPL-4CT 6V AGMs rated at 220-Ah (ditto again)... partly because I think I can stuff 4x of those into the same space where I now have 3x Odyssey Group 31 AGMs.

A quick glance suggests these 6Vs are all the same form factor, roughly equivalent... although I'm surprised at the capacity differences. This must need a cost/Ah calculation, once I get to shopping more seriously.

OTOH, switching to gel would add a bit more complexity or cost for me, either having to add another dedicated charger or having to swap out the other two battery banks at the same time, too.


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