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-   -   Trojan verses AGM (http://www.sailnet.com/forums/gear-maintenance/49535-trojan-verses-agm.html)

dsbentley 12-08-2008 08:25 AM

Trojan verses AGM
 
I have had 6 Volt AGM batteries in my boat in the Caribbean for 2 years. Somehow my Link 2000's have allowed my Freedom 25 to apperantly overcharge the batteries as they are buldging and wont hold a charge. I am told that 90% of the crusiers in this area use the Trojan 105's as they work the best and are half the price. Someone said that because the area were my battereies are located is not well vented, that I should not use the Trojans. Any advice on this matter?

SteveInMD 12-08-2008 08:38 AM

As far as venting - both AGM and wet cell batteries produce hydrogen gas when charging. That's why the battery box should be vented. The vent should be at the top of the box because hydrogen is lighter than air.

If you are going to do regular battery maintenance you will get the most bang for your buck with a good quality wet cell like Trojan. If you are going to install them and forget them, then go with AGMs. However, your charger must be setup for AGMs if you go that route.

sailingdog 12-08-2008 09:10 AM

The Link 2000 probably has nothing to do with overcharging your batteries, since it is a charge monitor, not a charge controller, unless you have the Link 2000R, which has an external regulator for your alternator. The Freedom 25 is probably configured wrong. :) Yes, you can set the Freedom 25 from the Link 2000.

How many batteries did you have in your house bank? The problem may be the size of the charger you're using. The Freedom 25 is an 130 Amp charger, and unless you've got four or more 6V golf-cart sized batteries, the size of the charger may be the problem. BTW, if you're going to go with Trojan T105 type wet-cell batteries, you'll need at least six for the charger to be about the right size. A battery charger shouldn't be more than about 20% of the battery bank's capacity for wet cells. Six T-105 batteries will be 675 amp hours of battery capacity, 20% of that is 135 amps.

As Steve has pointed out AGMs are probably a better choice if you neglect basic battery maintenance, but the Trojans will work very well if you care for them properly. More batteries die of neglect and abuse than ever die of old age. :)

JHJensen 12-08-2008 09:18 AM

Batteries: Wet Cell vs AGM, Hydrogen Gas
 
Quote:

Originally Posted by dsbentley (Post 413606)
I have had 6 Volt AGM batteries in my boat in the Caribbean for 2 years. Somehow my Link 2000's have allowed my Freedom 25 to apperantly overcharge the batteries as they are buldging and wont hold a charge. I am told that 90% of the crusiers in this area use the Trojan 105's as they work the best and are half the price. Someone said that because the area were my battereies are located is not well vented, that I should not use the Trojans. Any advice on this matter?

Sounds like your charging system needs to be gone over:eek:

Your battery compartment(s), no matter if you have wet cell or AGM are required to be vented. Wet cell batteries produce hydrogen gas while charging and lots of it if they are being overcharged.

AGM batteries only produce hyrodgen gas if they are being overcharged as what appears to have happened to yours. People( builders, some repair techs and those not in the know) sometimes think that because they do not produce hydrogen when all is working properly, they can be put anywhere. There are a number of cases where AGM types have been stuffed into unvented compartments and have overheated and exploded. A bad experience if you happen to be nearby or on top of them (as in under a bunk). It is ok to have them under a bunk, just make sure you have a proper ventilation system set up.

Both types of batteries have different charging requirements which your system (Link 2000) should be able to ajusted to when it is set up properly, which also includes temperrature compensation during charging.

ABYC Standard E-10 covers the requirements for proper procedures for storage batteries, including the Federal Regs. This will make your insurance company happy as well. :) Request that all work done on your vessel be done in accordence with ABYC Standards and applicable Fed (CFR) regs as well.

John
ABYC Master Tech.

Steve and SD are correct that you will get more bang for your buck with wet cells if you maintain them. On the other hand if your system is set up properly for the you will get very good service with the AGM batteries and not have to be adding water as you will have to with wet cells.

sailingdog 12-08-2008 11:00 AM

Quote:

Originally Posted by JHJensen (Post 413638)
...Steve and SD are correct that you will get more bang for your buck with wet cells if you maintain them. On the other hand if your system is set up properly for the you will get very good service with the AGM batteries and not have to be adding water as you will have to with wet cells.


If you over charge AGMs though, you can dehydrate the electrolyte and destroy the batteries very easily.

Omatako 12-09-2008 02:23 AM

Quote:

Originally Posted by sailingdog (Post 413632)
How many batteries did you have in your house bank? The problem may be the size of the charger you're using. The Freedom 25 is an 130 Amp charger, and unless you've got four or more 6V golf-cart sized batteries, the size of the charger may be the problem. BTW, if you're going to go with Trojan T105 type wet-cell batteries, you'll need at least six for the charger to be about the right size. A battery charger shouldn't be more than about 20% of the battery bank's capacity for wet cells. Six T-105 batteries will be 675 amp hours of battery capacity, 20% of that is 135 amps.

So based on this, 4 Trojans would be 450 amp hours so the charger should not exceed 90 amps? That's a worry.

I have only four T-105's in my house bank. I also have a Freedom 25 charger. I also have a 185 amp alt on my main engine which routinely pumps 140 amps into the house bank when it's a little soft. I can't say I've ever had an overcharge situation because of this. I monitor the whole lot via a Link 20. My batteries aren't gassing and I'm not losing a lot of water.

Most cars have a 65Ah battery driven by a 55 amp alternator. That's quite a bit more than 20%. Most are wet cells.

I always thought that the regulator decided what amperage was delivered to the batteries. Not the charger.

Am I wrong? Again?

HenkMeuzelaar 12-09-2008 03:15 AM

Just for the record: the title of this thread ("Trojan vs AGM") is confusing as Trojan has been making AGMs themselves for several years now.

In fact, we have had 5 Trojan 27G AGMs onboard since June 2006 and have been very happy with their performance as well as their proven ability to withstand tough operating conditions here in the South Pacific.

Flying Dutchman

sailingdog 12-09-2008 08:01 AM

Traditional wisdom for wet-cell batteries is not to charge at more than 20% of the battery bank capacity as a maximum charging rate. You can charge at a higher rate and get away with it...but it generally isn't too good for the batteries. AGM batteries have a much higher current acceptance rate and can often be charged at closer to 50% or so of battery bank capacity.

Some of the newer technology batteries can be charged at even higher rates.
Quote:

Originally Posted by Omatako (Post 414086)
So based on this, 4 Trojans would be 450 amp hours so the charger should not exceed 90 amps? That's a worry.

I have only four T-105's in my house bank. I also have a Freedom 25 charger. I also have a 185 amp alt on my main engine which routinely pumps 140 amps into the house bank when it's a little soft. I can't say I've ever had an overcharge situation because of this. I monitor the whole lot via a Link 20. My batteries aren't gassing and I'm not losing a lot of water.

Most cars have a 65Ah battery driven by a 55 amp alternator. That's quite a bit more than 20%. Most are wet cells.

I always thought that the regulator decided what amperage was delivered to the batteries. Not the charger.

Am I wrong? Again?


camaraderie 12-09-2008 08:49 AM

I would suggest that the problems with the current set of batteries may have been caused by a failure of one of the batteries cells which resulted in a cascade failure rather than one caused by the charger. Certainly have the charging system checked out...but recognize that batteries do fail.

I would suggest looking at the Odyssey AGM type batteries for the future as they can accept charge amperage well in excess of their rated capacity which will result in much faster charge times. The Freedom 25 can supply 125 amps and you can deliver ALL that amperage into ANY Odyssey battery. Thus with a 450 amphour bank 50% discharged and needing a 225 amp hour recharge...you could be fully recharged with the Freedom25 in two hours.

xort 12-09-2008 09:03 AM

Quote:

Originally Posted by JHJensen (Post 413638)
It is ok to have them under a bunk, just make sure you have a proper ventilation system set up.

John
ABYC Master Tech.

What do you mean by 'proper'?...

a. Venting out of the battery box into the under bunk area?

b. Venting out of the under bunk area into the living space?

c. Venting out of the box directly overboard?

d. Venting out of the under bunk area overboard?

e. Something else?


My boat has had batteries under the bunk since 1985, as designed by the factory. Am I about to die? :eek: ;)

Thanks


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