Battery Out-gassing question

[Stan Breaux]

I have a 1996 Catalina 36 MKII with two 4D batteries and a separate starting/reserve battery.

I'm about to replace the two 4Ds with 4 of the Duracell 6 volt golf cart bateries from Sams, but then this morning I started reading about battery "out-gassing", and now I'm wondering if I'm doing the right thing. I have my boat in acharter service, and they are advising me to go with the AGM batteries, but the cost is, of course, extremely high, not to mention all that MaineSail has had to say about AGMs.

Here is what I read about outgassing (from the Catalina 350ia board)...

"Never hear anyone say EG2's from Sams Club were better than T105's. Less expensive yes. Better value, perhaps. But, particularly with the batteries mounted inside where they are, I am a firm believer in AGM batteries that do not out-gas under ordinary conditions (will out-gas if extreme overcharging takes place).
An unventilated battery compartment under the nav seat is NOT the place (my opinion) for wet cell batteries."

and

"We put a pair of the EGC2's from Sam's into The Best of Times last year. If I happen to leave the charger on overnight, the CO alarm goes off from the outgasing of charging the batteries (usually at 2am!). If I were replacing ALL of the batteries, I would certainly consider Brett's suggestion with going with AGM battery banks. I just have to remember to turn the battery charger off before going to bed."

So what do you think?

Is outgassing really a problem?

- Stan

 

[Stan Breaux]

So I went back and read about 50 old posts about battery gas

It sounds like this will not be a real issue as long as my charger is not putting out more than 14.4 volts.

If I'm really missing something important, then please let me know.

- Stan

 

[Don S/V ILLusion]

You are not missing anything. As one indicator, Catalina has been locating batteries in interior spaces for decades. If they gas, there is a problem that needs to be addressed regardless of where they are located.

 

[Stu Jackson]

It seems you're aware of the pitfalls of AGMs. Good.

As noted, Catalina has made gazillion boats. Some of us, faced with this concern, simply add a few vents in the sidewalls of our battery compartments. I haven't. But maybe will. Boat's 26 years old and hasn't blown up or corroded.

 

[Maine Sail]

I have a 1996 Catalina 36 MKII with two 4D batteries and a separate starting/reserve battery.

I'm about to replace the two 4Ds with 4 of the Duracell 6 volt golf cart bateries from Sams, but then this morning I started reading about battery "out-gassing", and now I'm wondering if I'm doing the right thing. I have my boat in acharter service, and they are advising me to go with the AGM batteries, but the cost is, of course, extremely high, not to mention all that MaineSail has had to say about AGMs.

Here is what I read about outgassing (from the Catalina 350ia board)...

"Never hear anyone say EG2's from Sams Club were better than T105's. Less expensive yes. Better value, perhaps. But, particularly with the batteries mounted inside where they are, I am a firm believer in AGM batteries that do not out-gas under ordinary conditions (will out-gas if extreme overcharging takes place).
An unventilated battery compartment under the nav seat is NOT the place (my opinion) for wet cell batteries."

and

"We put a pair of the EGC2's from Sam's into The Best of Times last year. If I happen to leave the charger on overnight, the CO alarm goes off from the outgasing of charging the batteries (usually at 2am!). If I were replacing ALL of the batteries, I would certainly consider Brett's suggestion with going with AGM battery banks. I just have to remember to turn the battery charger off before going to bed."

So what do you think?

Is outgassing really a problem?

- Stan

Stan,

No, out gassing is NOT a problem when batteries are PROPERLY charged. If that guy is having out gassing issues with wet cells then he will DESTROY AGM batteries $$$$$$... AGM's will gas just as wet cells do except that when you gas AGM batteries you have no way to replenish the electrolyte. Out gas them enough and you've just burned a HUGE hole in your wallet.

On the standards front ABYC makes ZERO exemptions on battery compartment ventilation for VRLA AGM or GEL batteries when compared to flooded batteries. All three types must use proper ventilation as all three types CAN and do vent.

This is SIX YEARS of wet cells in the same compartment. These batts are also on solar so they charge every day of the 7 month boating season. They are also charged with a "dumb regulated" alternator. Do you see any corrosive effects from acid out gassing?

Here is a bare copper bus bar in that same battery compartment. Photo taken at year 5 and it still looks just as good today as it did then.

Often times when out gassing is an issue it is because an owner has "contaminated" the electrolyte when filling or checking SG. Chronic checking of SG or water levels introduces errant minerals to the electrolyte that can cause gassing to begin as low as 13.2V... Gassing should not happen until after 14.4V and until you hit 14.8V or so gassing is really a non-issue in a properly vented battery compartment. If equalizing banks then you'll want some serious ventilation.

Millions upon millions of flooded batteries are installed in cabins on pleasure, commercial and charter vessels world wide. Please don't let folks who likely do not have not a clue about boat electrics guide you on what batteries are "best" for you. I can say this because anyone advising AGM without some strong caveats, and without also telling you how to properly care for them to get the best life, or who insists AGM's are "safer" because they don't "gas" has not a clue about AGM batteries. Do your own research and make up your own mind.

 

[timvg]

Been using 4 Trojan T-105's since 2000. About every 4 or 5 years, we replace them, even thought they are still working well. Our battery charger is always on at the dock, and I hardly ever have to add water to the batteries.