Battery overheating

[Ranger06]

Quick question as I have no experience with the electrical system, but I'm learning!


I came onto the boat tonight, she had been hooked up to shore power for about 24 hours since I was last on her. I smelled a very strong sulfur smell but didn't think anything of it, thought maybe coming from the head...


Went sailing for a few hours, smell went away. We motored home for about 90 minutes. After docking and tying her down, I went below to clean up and there was the sulfur smell again.


Upon investigation, I determined it was one of my batteries. I have 2-78AH batteries in the house bank. Boat is a year old, factory batteries.


I'm assuming this is a bad battery? I haven't had any battery issues in a year and I've been living aboard in a marina.



Any help or advice would be much appreciated!


Thanks

[markcouz]

Yes it sounds like a bad battery that should be disconnected asap. To check disconnect both batteries and allow to settle for a few hours - I suspect that you will find that one settles to a low voltage.

This is often caused by a shorted cell within the battery, the charge voltage is then spread over 5 remaining cells instead of the normal 6 cells. The 5 cells are now being overcharged causing them to emit that gas smell. You would get the same effect by charging a battery at 17.28v (14.4/5*6).

Before disconnecting check your shore power charge voltage, you may have a problem there that caused the issue in the 1st place.

[GordMay]

Over-charging a lead acid battery can produce, both, heat, and hydrogen sulfide (H2S, rotten egg smell). The problem could be in the battery itself, or it could be that the battery is getting overcharged.

➥ https://www.cruisersforum.com/forums...ues-91385.html

[Ranger06]

"Yes it sounds like a bad battery that should be disconnected asap"


I've disconnected the shore power so nothing is charging. Should be ok until tomorrow, no?

[markcouz]

Yes, should be ok with no charge applied, but you need to disconnect the batteries as well because as long as they are connected in parallel the good battery will be hiding the problem of the bad battery - and also discharging into it as it attempts to maintain equal voltage.

Originally Posted by Ranger06

"Yes it sounds like a bad battery that should be disconnected asap"


I've disconnected the shore power so nothing is charging. Should be ok until tomorrow, no?

[markcouz]

... If you know which is the bad battery (because of high temp detected) then just disconnect that one for now if power needed overnight.

[markcouz]

...on a final note, Google H2S ( hydrogen sulphide) so that you know what you are dealing with.

[Ranger06]

Thanks everyone, I appreciate all the advice.

Think I’ll swap out the offender tonight and see how that goes.
Maybe an AGM upgrade!

[Dennis.G]

I had a voltage regulator fail on an old Chevy Camero. Overcharged lead acid batteries give off hydrogen sulfide which smells like rotten eggs. In my Camero it was the stink that let me know something was wrong. Had to replace both the regulator and battery.

[MarkSF]

I had a battery that did this, and it was still hot and making wierd gurgling noises 12 hours later. People do report battery explosions under these circumstances.

Is it hard to get it off the boat? If practical, do so.

[Stu Jackson]

Originally Posted by Ranger06

>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>

Maybe an AGM upgrade!

Maybe not worth the cost. Consider carefully, you may not need to spend the extra, way extra $$$.


AGM Batteries - Making The Choice (from Maine Sail)

https://forums.sailboatowners.com/in...choice.124973/

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
https://forums.sailboatowners.com/in...teries.133773/

Additional Observations on the Limits of AGMs http://c34.org/bbs/index.php/topic,5....html#msg63004

[Ranger06]

As luck would have it, there aren't any of the same (Exide) batteries in the UAE. What I did was sway the start battery and the hot battery out (same make and model). Then I bought a "blue top" optima battery to use as the start battery.

[GordMay]

Originally Posted by Ranger06

... Then I bought a "blue top" optima battery to use as the start battery.

If it’s a BLUETOP with a Dark gray case, then it’s a starting battery; if it has a Light gray case, then it’s a dual-purpose (start/house) battery.

[Ranger06]

Looks like I'm back in business. Been on shore power for a few hours now and no rotten eggs, exploding batteries or alarms from my battery monitor.


Again, thanks for all the help. This forum is hands-down the best resource I have found for my adventure into this cruising lifestyle.


Appreciate it!

[a64pilot]

If you stay in a Marina and only day sail, you will be fine with AGM’s especially if it’s only two batteries.
However probably both of your house bank batteries are gone, when one goes it usually takes the other with it, sort of like a flashlight, you need to replace them all, not just one.
If Optima’s are the most available, they are a very good battery, not the best for cruising, but for day sailing and maybe the occasional overnight, they are great.

I thought yellow top were deep cycle, red starting and blue a hybrid.
I would want the yellow tops myself