AGM Batteries

[Not Sure]

The fact is, 'marine batteries' aren't really deep cycle batteries at all, and are just slightly better than automobile batteries for 12v electrical systems. Worst to best is as follows (using standard nomenclature):
automotive battery (i.e. Sears)
marine battery (i.e. Sears Marine)
golf cart battery (i.e. T-105)
fork lift battery (i.e. L-16)
industrial cells (i.e. IBE/Hawker)

...the last three (industrial, golf cart, & fork lift) being true 'deep cycle' batteries. And deep cycle is actually a misnomer, as your batteries should be kept above 80% charge always, and should absolutely never fall below 50% charge.

[bobfnbw]

Originally Posted by Not Sure

The fact is, 'marine batteries' aren't really deep cycle batteries at all, and are just slightly better than automobile batteries for 12v electrical systems. Worst to best is as follows (using standard nomenclature):
automotive battery (i.e. Sears)
marine battery (i.e. Sears Marine)
golf cart battery (i.e. T-105)
fork lift battery (i.e. L-16)
industrial cells (i.e. IBE/Hawker)

...the last three (industrial, golf cart, & fork lift) being true 'deep cycle' batteries. And deep cycle is actually a misnomer, as your batteries should be kept above 80% charge always, and should absolutely never fall below 50% charge.

Well that may have been true in the past, but the current sears marine battery is a oddssy battery TPPL in disguise.

http://www.sears.com/shc/s/p_10153_1...rine+Batteries

ODYSSEY Batteries - Battery Specifications

Now I can't say for sure how it will pan out over time, but if it turns out like I think it will, it will prove to be a better battery than the others you mention, when price, safety, capacity, time to recharge ect is taken into account.
I was a big believer in Trojan t105's in the past. After taking on water, and having those batteries leak all over the cabin, I don't think so ever again.
The future is in new battery technology, not past. Wet lead acids have their place, but I believe not on my boat.

Bob

[Not Sure]

Originally Posted by bobfnbw

Well that may have been true in the past, but the current sears marine battery is a oddssy battery TPPL in disguise.

http://www.sears.com/shc/s/p_10153_1...rine+Batteries

ODYSSEY Batteries - Battery Specifications

Now I can't say for sure how it will pan out over time, but if it turns out like I think it will, it will prove to be a better battery than the others you mention, when price, safety, capacity, time to recharge ect is taken into account.
I was a big believer in Trojan t105's in the past. After taking on water, and having those batteries leak all over the cabin, I don't think so ever again.
The future is in new battery technology, not past. Wet lead acids have their place, but I believe not on my boat.

Bob

Boat Battery Basics: Boats and Yachts Maintenance and Troubleshooting

Boat batteries regardless of type should be contained in a covered battery box to protect them from water.

[sailing now]

Personally, I'd be leery of Chinese batteries (and alot of other stuff..drywall, baby toys, etc) I have had Lifeline AGM's On second set now of house batteries. First set 7 years. I only replaced them because I added a third and we were heading to the Bahamas for the winter. My AGM engine start and the little AGM for genset start are now 10 years old and still going strong.

[Strygaldwir]

Hmm.... I use my deep cycle batteries regularly for starting my engines. The concern is their ability to deliver the necessary amperage over very short periods of time. The bank is 750 Ah, I think they handle the load of the very small starters reasonably. I do have a dedicated starter battery that I use the GREAT majority of the time. I just like to be sure that if needed, I can use the house banks to start the engines if necessary. Having this ability means I did not have to install two starter batteries, one for each engine. The starter battery supplies both engines. Having said all that, I'd not install deep cycle batteries as a starting battery. Too much weight, cost, and bulk.

Surrette has just recently announced an AGM solution. I'll check the cost of them. They look pretty good. As suggested, Fullriver has received consistently good review from knowledgeable folks here (Rick). I will not hesitate to use them.

[billyehh]

Just a postscript. Lifeline batteries are made in the USA and are considered the equivalent of the original German AGM's. You pays a little more and it pays you right back. There are other high quality AGM's, but these are the ones that I know and have researched

[Rick]

Jedi's last paragraph says it all regarding a start battery. The capacity is essentially irrelevant because it only takes about 1/2 Amp-hour or less to start the largest diesel engine given the folowing parameters:

The important parameters for a good start battery is electrolyte specific gravity (directly translates to terminal voltage and previously it has been noted that AGM batteries generally have higher terminal voltage than do flooded-cel batteries); internal cell resistance (extremely important); and surface area in conjunction with temperature and motility of electrolyte carriers.

Agm batteries excell in all of these areas over even flooded-cell start-only-start batteries which is why Jedi's report is testimony to a small high-quality start battery being able to start a diesel faster than a poor quality large bank for starting.

[bobsadler]

came across these batteries which look interesting and, by uk standards, are competitively priced

Elecsol Batteries - Elecsol Batteries

has anyone any experience with them

[bobfnbw]

Gord, good point.
Still a suficently large bank of deep cell batteries should be able to start a diesel that is in good shape. Mine started in the first 3 seconds or so.
Now if a lot of cranking is needed... then yeah maybe not so good.
A dedicated start battery is always a good idea anyway.

[s/v Jedi]

Guys,

It isn't a problem to start an engine with deep cycle or traction batteries when the bank is big enough. You need 20% higher Ah rating when doing that as compared to a real starter battery. So, 240Ah instead of 200Ah for example.

The problem (which might be history with all the improvements they have now) is that a traction or deep cycle battery has few thick plates, whereas a starter battery has many thin plates (much more plate surface area). The thick plates can bend if drawing lots of current from it, so much that they can create an internal short. This is all old-tech lead-acid and I don't think this can happen with AGM. The more surface area, the more current can be delivered. Starter service is lots of current for a very short time, house service is much less current for very long times. These are different uses of a battery and if you have a separate starter battery, it's better to buy a real starter battery.

My 140 hp starts in a fraction of a second on the Odyssey (100Ah) starter battery (less than 0.5 second) and takes just over a second when I start from the house bank, which is a series/parallel combi of 6 x Trojan L16, just under 1200Ah. So, the 100Ah Odyssey outperforms the 1200Ah traction bank.

cheers,
Nick.

[chris_gee]

There seems a bit big a gap between the prices to be comparing like with like.
"The price difference is huge from under $500 for chinese made to closer to $1500 for Deka, Mastervolt etc."
I don't know those brands but compared a couple of chinese gp 27 at around $560US equivalent for two to Lifeline at around $850. Lifeline appear to be very good. Maybe the chinese ones are good or not, I would check out the maker and see what other labels they make and ask around. To get to 1500 though you are talking another class - Rolls? That probably is not a fair comparison. Your real choice is say $560 or 850. How much the saving is important to you versus the uncertainty over brand is up to you. Say the lifelines last 6 years cost is 142 pa that equates to 4 years on the others. Real cost though depends on how you handle them.

[Captain Bill]

I recently had an interesting experience with lifeline group 27 AGMs. I had two lifeline 4Ds for my house bank and a group 27 for each engine. After 7 years the group 27s failed within a week of each other. I'm not complaining about the lifespan mind you, but the battery shop diagnosed them as having died from sulfation, which they attributed to being charged at low amperages and voltages over a long period. I've noted that these batteries discharge only a miniscule amount as my engines start instantly. The charger never gets out of float mode. My house bank on the otherhand (the same age) is discharged regularly to about 50% and gets a nice 3 stage charge. It shows no signs of sulfation. The battery shop suggested that I equalize my starting batteries about twice a year to prevent sulfation.

[Albro359]

My understanding was that AGM batteries don't suffer from sulphation and therefore don't need equalisation...and in fact the equalisation voltages can damage them

True or not ...anyone know for sure ?


Alan

[GordMay]

See the
Concorde “LifeLine” AGM Battery Manual
➥ http://www.lifelinebatteries.com/manual.pdf

See item 5.5 “Conditioning” (‘Equalization’), on page 20.

and Steve D’Antonio's excellent article
The ABCs of AGMs:
How to use and maintain absorbed glass mat batteries
➥ http://www.zimmermanmarine.com/docs/AGM%20article.pdf

[Albro359]

Thanks Gord..as always...on the button...

Still the equalisation deal with AGMs is not totally clear...some say yes, some say no...and the big problem seems to be the venting of the gasses generated during the equalisation process....AGMs should not vent..most say

So we still don't know !

Alan