Chassis battery sulphur smell

[Hymerman]

A week or so ago when parked on shore power at a campsite I noticed a bad smell coming from the front of the motorhome and popped the engine cover to smell sulphur and hear the chassis battery fizzing.

Made me consider the shore power (Fleetwood Flair 2007 - I gather shore power also charges chassis battery) was over-charging the chassis battery (inteli power 9155). I disconnected the battery for a while (blade switch) and added some distilled water as one of the cells seemed low.

Yesterday when I had been on the road for 9 hours I stopped and smelled the same smell - chassis battery stink and fizzing sounds - this after driving for around 5 hours.

As the battery seems to be smelling and fizzing on both shore power and alternator - would you guys agree it is a battery problem, rather than the inteli-power or alternator?

[Canadian_Rainbi]

9.5 volts is at least 2 shorted cells. The charger was busily pushing current trying to charged those cells so gassing like mad. Good thing you bought a new one!

[Hymerman]

Checked the chassis battery the next morning after leaving it disconnected from shore-power - 9.5V. Took it and got it changed, had the alternator checked at the same time and all OK.

[Hymerman]

naturist wrote:
Those are signs of a battery that is being overcharged and/or is drying out. #1 step is to check that the water level is up where it is supposed to be. #2 step is to find out what voltage the charger is laying on it, both as the engine is running and as the shore power is plugged in and the engine is off. You will need a voltmeter for that.

It is possible that the battery itself is shot. It is also possible that the charger(s) are bad. A voltmeter will tell you which it is.

I had already added distilled water. Just checked on shore power:
Leisure batteries getting 13.5V (pair of T125's)
Chassis battery getting 13.5V and fizzing still (so again turned off the blade switch afterwards).

[westend]

Definitely a battery problem and, as posted, replace it immediately. If the battery has a semi-conductive short between negative and positive plates, it will function, somewhat, but if the plates decide to weld themselves together, there is the possibility of a battery case explosion.

[beemerphile1]

Most likely an internal short causing overcharging. Buy a new battery immediately!

[hmknightnc]

Internal short in battery. Replace it before you get an even nastier surprise.

[ksg5000]

Maybe an internal short .. if so time for a new battery. Have the battery tested - it's free.

[midnightsadie]

sounds like the battery needs water, and by noww needs replaced.

[naturist]

Those are signs of a battery that is being overcharged and/or is drying out. #1 step is to check that the water level is up where it is supposed to be. #2 step is to find out what voltage the charger is laying on it, both as the engine is running and as the shore power is plugged in and the engine is off. You will need a voltmeter for that.

It is possible that the battery itself is shot. It is also possible that the charger(s) are bad. A voltmeter will tell you which it is.