Batteries - strong smell/fizzing sound

seansea

seansea

Well-Known Member
Joined
14 May 2006
Messages
69
Location
CI's
Visit site
Just ending a week's cruise and noticed a strong noxious smell which I traced to the service batteries after hearing a strange fizzing sound like a chemical reaction. Have been plugged into shorepower for about 7 hrs. Never come across this before One of the AGM 175 amp batteries has expanded slightly. They are about 7 years old. They are holding their charge but maybe on the way out? Have not changed anything.
 
Last edited:
seansea said:
Just ending a week's cruise and noticed a strong noxious smell which I traced to the service batteries after hearing a strange fizzing sound like a chemical reaction. Have been plugged into shorepower for about 7 hrs. Never come across this before One of the AGM 175 amp batteries has expanded slightly. They are about 7 years old. What's going on?
Click to expand...

You almost certainly have a shorted cell in the expanded battery. Turn the mains charge off, vent the battery space and stay clear until it settles down. Then, disconnect the negative cable from the suspect battery and measure the voltage, if it's around the 10v mark it confirms it has a shorted cell. It needs to be replaced, but at 7 years the others will be past their best, so i'd replace them all.
 
Rotten egg smell
One of the first symptoms of a problem with the battery is a rotten egg smell. Conventional acid lead automotive batteries are filled with a mixture of water and sulfuric acid. ... This may cause the battery to overheat or boil, which will produce an unpleasant smell, and even smoking in more severe cases.Jan 4, 2016

This article is worth reading
Symptoms of a Bad or Failing Battery | YourMechanic Advice
 
PaulRainbow said:
You almost certainly have a shorted cell in the expanded battery. Turn the mains charge off, vent the battery space and stay clear until it settles down. Then, disconnect the negative cable from the suspect battery and measure the voltage, if it's around the 10v mark it confirms it has a shorted cell. It needs to be replaced, but at 7 years the others will be past their best, so i'd replace them all.
Click to expand...
Many thanks, just found a source for replacement batteries. Now have to fit in v. tight Battery box. New ones seem to be slightly wider.
 
PaulRainbow said:
You almost certainly have a shorted cell in the expanded battery. Turn the mains charge off, vent the battery space and stay clear until it settles down. Then, disconnect the negative cable from the suspect battery and measure the voltage, if it's around the 10v mark it confirms it has a shorted cell. It needs to be replaced, but at 7 years the others will be past their best, so i'd replace them all.
Click to expand...
Paul, you often reccomend ( or at least say you have recently fitted) a particular Hankook group31 battery costing circa £125. That particular battery now seems out of stock everywhere, and one supplier I contacted said that this was a long term problem. Can you tell the group what service battery you now favour.
Thanks
 
Rafiki said:
Paul, you often reccomend ( or at least say you have recently fitted) a particular Hankook group31 battery costing circa £125. That particular battery now seems out of stock everywhere, and one supplier I contacted said that this was a long term problem. Can you tell the group what service battery you now favour.
Thanks
Click to expand...

The ones i have been fitting are these: Hankook XL31 Dual Purpose Leisure Battery - Battery Megastore

Showing out of stock now, as you say, i've fitted several of them in the past few weeks, might be why they are out of stock :)
 
  • Like
Reactions: pvb
seansea said:
Just ending a week's cruise and noticed a strong noxious smell which I traced to the service batteries after hearing a strange fizzing sound like a chemical reaction. Have been plugged into shorepower for about 7 hrs. Never come across this before One of the AGM 175 amp batteries has expanded slightly. They are about 7 years old. They are holding their charge but maybe on the way out? Have not changed anything.
Click to expand...
This happened to me last season. Left in a marina on shore power on for a week. Came back to boat and the battery had a crack in it. Strong smell of eggs / acid.

Caused by dead battery which under reads voltage so gets the full charge treatment. It can never get to full voltage so eventually it over heats spraying out hydrochloric acid and possibly causing a fire. I had a temp sensor fitted but it didn't stop it.

I won't be leaving the boat connected to shore power unattended again.

S
 
You must log in or register to reply here.

Share this page

Top