Battery overcharging

[bmac]

I replaced four of my six batteries in May of this year, they are now 4 months old. This Friday my CO alarm went off in the middle of the night. Having been through this earlier this season with a fried bow thruster battery charger over charging those batteries I had a sense it might be related to another overcharge condition, so I shut both battery chargers off and went back to sleep. Saturday morning I first checked my bow thruster charger and batteries. All was well there. I next checked my 12V charger and it was carrying a light load. I turned it off and checked each of the house/starting banks. The port bank was fine but as soon as I opened the first battery on the starboard bank I noticed two things, pretty strong sulfur odor and the water in the cells slightly bubbling. The other battery on that bank appeared fine. I filled the first battery with water and turned the charger back on. Same thing happened very early early this morning, CO detector went off. I checked the battery again and about an inch of water had gassed off overnight. I've left the charger off for the time being. Since it's only the one battery out of four that's doing this I am assuming it's a battery and not a charger problem. These batteries are wired in parallel. I'm curious as to what would cause a battery to do this. Internal short? Could it still be a charger issue? I'm hoping to get the battery replaced under warranty if that is indeed the problem. Any ideas or am I correct that it is likely the battery? :huh:

 

[O!Richard]

Hi Brian,

Do you have a 24 vdc system on the boat? If so it could be the battery equalizer (Vanner) having gone bad. We had this occur this spring.

 

[bmac]

Hi Brian,

Do you have a 24 vdc system on the boat? If so it could be the battery equalizer (Vanner) having gone bad. We had this occur this spring.

Thanks, Richard. I do have a 24V system but that is for the bow thruster. This bank is 12V and has a seperate charger from the 24V system.

 

[O!Richard]

Brian,

Good practise would be to isolate each battery and charge seperately (not parallel other than thru an Isolator). Typically batteries are not identical and charge at different rates. An exception of course is when the are in series. I also in my boat switch to AGM Odessey Batteries (1/2 the physical size of an 8D with ssame cranking capacity) The yare dry and require no maintenance and they charge using the same lead acid charger.

Richard

 

[twyant]

If one battery is bad the charger will keep trying to charge it making it over charge the others. You should always change all the batteries together.

 

[Loneranger]

I had my deep cycle battery go bad last month at less than a year old. I never got a good explaination as to the problem with the battery. When I have had batteries go with a bad cell I would usually have less than 10 volts on the battery. This one had 12.9 volts even when load tested, yet it outgased hydrogen sulfide like crazy. I tested my charger per instructions sent to my by Promariner and it seemed to be ok. I replaced the battery and have not had any further problems. So I guess the battery was just beginning to fail? I still have not received a satisfactory explination.

I did not realize the CO monitor would pick up hydrogen gas. I went crazy searching for an exhaust leak for a little bit.

John

 

[bmac]

I had my deep cycle battery go bad last month at less than a year old. I never got a good explaination as to the problem with the battery. When I have had batteries go with a bad cell I would usually have less than 10 volts on the battery. This one had 12.9 volts even when load tested, yet it outgased hydrogen sulfide like crazy. I tested my charger per instructions sent to my by Promariner and it seemed to be ok. I replaced the battery and have not had any further problems. So I guess the battery was just beginning to fail? I still have not received a satisfactory explination.

I did not realize the CO monitor would pick up hydrogen gas. I went crazy searching for an exhaust leak for a little bit.

John

I'm guessing this one battery has begun to fail. It's offgassing hydrogen sulfide like crazy and, yes, apparently the CO detector is excited by the hydrogen gas. I never knew it until my bow thruster battery charger stayed in charge mode and fried those two batteries.

 

[bmac]

If one battery is bad the charger will keep trying to charge it making it over charge the others. You should always change all the batteries together.

All four of the batteries, two banks of two in parallel, supplied by the same charger were changed at the same time. The other two batteries are wired in series and are charged by a seperate 24V charger for the bow thruster.

 

[twyant]

I had one go bad and it blew up what a mess but it was two years old the charger never shut off luck I was in the back yard and saw smoke coming out bilge vents and went down and shut down everything