# Sulfur smell from batteries while charging?



## wmflyfisher (Jan 17, 2008)

This issue popped up with me last summer but I never got a chance to look into it. Today was the first time that I had run the boat in a while and I noticed it again. While running the engine (F150) after about 30 minutes I start smelling a sulfur smell in the console. 

Two battery system (house & starting). I checked the voltage on both while running and the house was showing 13.9, starting 14.8. 

What's going on here?


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## brnbser (Oct 1, 2007)

It's a bad battery, that's what causes the sulfur smell. Have them tested, one is bad.


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## dustyflair (Nov 11, 2011)

could be over charging too. Had that happen before and had that smell.


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## Chapman5011 (Mar 7, 2013)

I've noticed this smell before. More than once. Maybe I was charging a seadoo or lawn mower battery, but I know exactly the odor your referring to. 
My opinion, is that the battery is over charged a little, because when you can smell that smell, if you put your ear up to the battery, you can hear a boiling/bubbly sound inside the battery.


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## wmflyfisher (Jan 17, 2008)

Thanks guys. Will have them both tested.


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## Hopin4aboat (Jul 5, 2009)

Bad battery, I would figure out which one and get rid of it before it goes boom and covers everything in acidy crud.


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## dustyflair (Nov 11, 2011)

Test the batteries with the motor running also...


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## wmflyfisher (Jan 17, 2008)

dustyflair said:


> Test the batteries with the motor running also...


How can I do this?


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## 153 Large fish (Nov 30, 2013)

The smell is sulfuric acid vapor....did you check the water levels?..if they are low fill to a quarter inch from the top of the battery with DISTILLED water not tap water...


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## wmflyfisher (Jan 17, 2008)

153 Large fish said:


> The smell is sulfuric acid vapor....did you check the water levels?..if they are low fill to a quarter inch from the top of the battery with DISTILLED water not tap water...


Yep levels are good in both.


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## 153 Large fish (Nov 30, 2013)

Must be a dead cell in one battery...be careful, this situation is why there's a warning stamped on the battery about explosive gasses etc...


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## Spoolin Up (May 3, 2011)

In my opinion, i am not a scientist, but if they charge too fast they start gassing. Your batteries may not be bad, be careful with them at all times. I had one blow up on me before.


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## 153 Large fish (Nov 30, 2013)

Could it be charging too fast by the motor?...is there a regulator on this model?


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## RMS (Dec 9, 2008)

14.8 volts is getting up there, normally about 14.4 is the max recommended charging voltage.

And yes, the fumes are corrosive and explosive.

Like Big Daddy, I also had a battery blow up once as I stood over it in my dad's truck when I grabbed one of the cables to check the connection. It didn't know the post had broken and when I grabbed the cable it sparked and the top of the battery blew off. Back then gas stations had water hoses next to the pumps so I grabbed the hose and gave myself a shower on the spot.

As Big Daddy says, always treat a battery with respect!!


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## WhyMe (Apr 21, 2013)

I would charge both batteries up. Then put a load tester on them. You'll find the bad battery.
Whyme 
MakomyDayo


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## 60hertz (Oct 1, 2007)

Over-charging a lead acid battery can produce hydrogen-sulfide (H2S).

The gas is colorless, very poisonous, flammable and has the odor of rotten eggs. 

It is heavier than air so it will accumulate in your center console, bilge, hatch, battery box, etc... SO DON'T STICK YOUR HEAD DOWN or IN THERE.

Also, your nose gets used to it pretty quick, so just because the smell goes away don't think the gas is gone until you've vented the compartment very well with fresh air.

Unfortunately, by the time your battery starts producing H2S from overcharging, the battery is damaged and needs to be replaced.

I would also replace your battery charger too! If it's an "automatic" style charger then it's malfunctioning - this is probably what caused your battery to fail.


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## brnbser (Oct 1, 2007)

could just be gassing from overcharging but typically when that happens, it's already killed the battery and it's bulging on the sides. DO NOT load test the battery with the engine running. You can't test the battery with the engine running, only the charging system. I work at Autozone and test A LOT of batteries.


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## wmflyfisher (Jan 17, 2008)

Neither one of them are bulging or visibly bubbling but I'm going to remove and test both as soon as I can. Thanks guys. Not going back out until this issue is resolved.


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## Chet88 (Feb 20, 2008)

Yep bad battery. My Golf Cart started doing it and I couldn't even walk into the garage it smelled so bad.

I would just replace them both. Cheap insurance for offshore fishing.


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## speckledcroaker (Mar 23, 2012)

Wirelessly posted

If it's stinkin time to replace it. It's fried. If they are both the same age replace both. I would not even bother with testing.


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## 60hertz (Oct 1, 2007)

60hertz said:


> Over-charging a lead acid battery can produce hydrogen-sulfide (H2S).
> 
> The gas is colorless, very poisonous, flammable and has the odor of rotten eggs.
> 
> ...


Your charger has damaged your batteries. If you don't replace the charger it's going to destroy your new batteries too.


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## wmflyfisher (Jan 17, 2008)

Just had both batts load tested and both tested good but he said both were in their last 25% of life. Going to replace them and hope that's the issue.


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## amarcafina (Aug 24, 2008)

Vent the bilge area better.


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