Compare Glass Mat and AGM Batteries

[David M]

I have found that the West Marine store brand 8-D's last 5 to 6 years. I would imagine their smaller batteries come from the same source. I think they are the best bang for the buck...especially if you can buy them through Port Supply or know someone who has a Port Supply account.

That's a great term, "perfection paralysis". I get it myself sometimes.

[sandy daugherty]

There is a Russian expression that says "better is the enemy of good enough." The Mig 17 was an excellent example of how well this approach this works.

Give a lot of weight to warranties. And then figure a way to weigh where you have to go to take advantage of those warranties. I went with Deka 17" tall L16's, bought from West Marine, because they gave me the most amp hours within the limits of my battery space and there are lots of West Marine stores that will honor that warranty. I made up my own cables at the store, and they took an extra 15 minutes out of my day.

A watering system was essential; even with lowering the base the batteries sat on, I only have 3" above the batteries, tucked back under the helm seat. They are still very hard to visually check.

[Extemporaneous]

Originally Posted by bobfnbw

A 6v trojan weighs in at ~65 lbs, and has 220 amphours at the 20 hour rate.
2 therefore = the same as a 8D, but I can move them myself.

Wouldn't two smaller 12V in parallel get you to the same place + or - ?

Originally Posted by bobfnbw

Far as I know, a good quality flooded lead acid battery will far outlast the AGM.

See attached. I'm certainly not suggesting that it is correct, as a matter of fact, I would suggest it is COMPLETELY bias considering where it is from. I have though seen similar claims by others. Who knows? There are likely soooo many variables, with the largest being charging regime and maintenance.

Originally Posted by bobfnbw

My 2 cents, but don't take it to the bank, its not worth much.
Bob

Our monies likely would exchange at par on the open market.

Thanks,
Extemp.

[bobfnbw]

extemp,
Looking at trojan gell cells vrs wet cell I show that in the group 31 6 trojan gell cells will be 612 ah and weigh 414 lbs. 8 would be 552 lbs and give 816 AH.
Don't have figures for cost, but I is I believe at least 1.5x the cost of the T105.
8 of the T105's would weigh 496 lbs and give 900 AH.
T105s around here cost about 175 each last time I checked. So 8 would be ~1400.
One 4d lifeline battery at defender 210 ah cost 730 or 2920 for 4.

Many threads I have read state that their agm batteries have not lived up to their claim and are not good for deep discharges. Defender lists them as more for powerboaters that do not deeply discharge their batteries.


So, to me, the wet cell battery is the best overall deal, unless you can afford it, then the gell cells.
With hydrocaps the maintaince goes down, the perfomance per dollar is higher, and they are easy to lug around. Sure you might only move them twice, once when you install them, and then again when you take them out, but who wants to have to carry large heavy batteries. I prefer to be able to do things by myself if I can, and 65 lbs is managable.

Good luck in what ever way you go, and let us know what you pick please.

Bob

[Extemporaneous]

Originally Posted by bobfnbw

extemp,
Looking at trojan gell cells vrs wet cell I show that in the group 31 6 trojan gell cells will be 612 ah and weigh 414 lbs. 8 would be 552 lbs and give 816 AH.
Don't have figures for cost, but I is I believe at least 1.5x the cost of the T105.
8 of the T105's would weigh 496 lbs and give 900 AH.
T105s around here cost about 175 each last time I checked. So 8 would be ~1400.
One 4d lifeline battery at defender 210 ah cost 730 or 2920 for 4.

Many threads I have read state that their agm batteries have not lived up to their claim and are not good for deep discharges. Defender lists them as more for powerboaters that do not deeply discharge their batteries.


So, to me, the wet cell battery is the best overall deal, unless you can afford it, then the gell cells.
With hydrocaps the maintaince goes down, the perfomance per dollar is higher, and they are easy to lug around. Sure you might only move them twice, once when you install them, and then again when you take them out, but who wants to have to carry large heavy batteries. I prefer to be able to do things by myself if I can, and 65 lbs is managable.

Good luck in what ever way you go, and let us know what you pick please.

Bob

Thanks, Bob.
I don't doubt your numbers, however, there are two things that make flooded a show stopper.

• Poisonous gas when the acid is mixed with salt water (batteries will be in the bilge).
• The MUCH higher acceptance rate of AGM's.

I VERY much appreciate you pointing out how much those two points are costing me, I feel much better now!

Just kidding, it's all good, thanks.
I'll definitely post where my money is wasted.

Extemp.

[motion30]

Shop around some. The lifelines can be had at a deep discount. I was quoted just yesterday at $550 for an 8 d

[bobfnbw]

Originally Posted by motion30

Shop around some. The lifelines can be had at a deep discount. I was quoted just yesterday at $550 for an 8 d

Where did you get that quote from motion ?

With that kind of price, I might just reevalute AGMS
The out gassing is a issue I agree.
Never heard of it being a problem though. Of course, it could still happen.

Bob

[bobfnbw]

AH one more thing.
Nothing has been said about using hydrocaps or water miser caps.
These keep gas venting to a minimum, decrease the amount of water that you need to add, helps keep moisture out.
Water Miser Battery Caps
Hydrocaps - Battery gas recombiners

Adds to the cost of the battery though.
Bob

[motion30]

Originally Posted by bobfnbw

Where did you get that quote from motion ?

With that kind of price, I might just reevalute AGMS
The out gassing is a issue I agree.
Never heard of it being a problem though. Of course, it could still happen.

Bob

AMS batteries Hollywood FL. 954-983-8605

[Extemporaneous]

Originally Posted by motion30

AMS batteries Hollywood FL. 954-983-8605

Shipping to Canada might up the price a bit. Or a lot.

Extemp.

[camaraderie]

Originally Posted by Extemporaneous

See attached. I'm certainly not suggesting that it is correct, as a matter of fact, I would suggest it is COMPLETELY bias considering where it is from. I have though seen similar claims by others.

Yup...pretty graph but innacurate or biased in the extreme. Of course the cheapest wet cells won't last long...but neither will Lifeline give you 1000cycles at 50% discharge.
For example Trojan...which sells BOTH AGM and WET says this:

"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. "

[Extemporaneous]

Originally Posted by camaraderie

Yup...pretty graph but innacurate or biased in the extreme. Of course the cheapest wet cells won't last long...but neither will Lifeline give you 1000cycles at 50% discharge.
For example Trojan...which sells BOTH AGM and WET says this:

"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. "

Yes and where are Trojan's margins better? And as in my previous post "There are likely soooo many variables, with the largest being charging regime and maintenance." What is Trojan considering here.
Don't get me wrong, I am NOT defending or denying anyone's published information, it does however contribute to another statement I made at the beginning "struggle with sales bs vs fact," which leads me to, likely some of the best advice given.

Originally Posted by Chief Engineer

Keep things simple, don't believe all the hype, talk to other sailors.

Which through this forum, is what I'm doing. That along with the specifics of my situation.
Please keep more first hand information coming.
Thanks,

Extemp.

[s/v Jedi]

I would love to have gel's that perform the same or better than my current wet L16's. Tell me that there are gel's in L16 size!

We have flooded our wet L16's with fresh water once. The damage was all the cables connected to them (lugs eaten away). The strange thing is that even though they were completely under water for a week or so, after pumping the water out (cats flipped switch of bilgepump to OFF and opened faucet during our absence...) it turned out there was no extra water inside them!!! Can anyone explain that? Are the vent-holes in the caps one-way?

cheers,
Nick.

[sandy daugherty]

If the batteries weren't submerged very deep, the surface tension on the air bubble in the caps vent would prevent more than a few drops of water intrusion. If the water temperature fluctuated a bit, or you had a serious frontal passage, there might have been a different outcome.