Hot Smelly Flat Battery.

[frank rabbets]

We parked our 5 year old Golf for 1 hour. On getting back in the battery was flat so we were unable to start it. I decided to lock up manually but that set the alarm and indicators off. We went to get the 80 for a jump start and got back 15 minutes later. Alarm and indicators still weakly going off. Now here is the part I don't understand. On opening the VW bonnet there was a strong smell of hydrogen sulphide and the battery was very hot. Is that normal with a flat battery with very little draw on it? I'm hoping there is nothing wrong with the car itself.

Car is only used on short journeys, usually of less than 5 miles.

Thanks.

 

[joinerman]

Sounds like the regulator on the alternator has cooked your battery Frank

 

[Towpack]

The smaller of the 2 batteries on the works Transit went exactly the same way a couple of months back. The main (starter) battery was fine. The batteries are under the driver’s seat and the smell was overpowering. Had to drive it to the garage with both windows fully down. One of the plates had “gone”, whatever that means. Possibly shorted internally?

 

[StarCruiser]

Either of the above. Multimeter when charging, across the battery will tell the tale.

 

[frank rabbets]

Thanks. There's a little old fashioned shop a few miles away where they test batteries and alternators. They also keep a huge range of batteries so tomorrow I'll pay a visit and sort it. Battery will be on charge over night.

 

[joinerman]

I'd be careful charging it overnight Frank, at least put it somewhere where it can't do any damage if it goes bang. just saying.

 

[StarCruiser]

JM is right. You could well come back to a nasty acidic mess or a hole where the battery once stood if on a conventional charger. The modern ones just throw their crocodile clips up in the air and refuse point blank to get to work if there’s anything amiss with the battery.
I’d keep an eye on it if I were you.

 

[frank rabbets]

I did think there would be a bang when I jumped it.

We were stuck in a narrow cul-de-sac road with the 80 parked alongside so we were totally blocking the traffic. Loads of revving engines, shouting and tooting so I put my ebay ex police jacket on......total silence lol. I did check the charging last night and the battery was cool and ameter nearly on zero.

 

[StarCruiser]

Any sign of life in it this morning Frank? Was the ammeter showing any charge at all when first connected?

 

[frank rabbets]

Ammeter at .5 amp last night when first connected then zero this morning but engine would not start as battery dead. Stuck in the garage with electric hand brake stuck on! Soon sorted with another jump though. Multimeter showed 14.7 volts with engine running with said dead battery.

Everywhere closed except VW who had no battery and Halfords who had got the battery. Get this £157 battery + £25 to reset the stop/start system. Ammeter now shows 12.7 volts with engine running and no increase at higher RPM.

Curiously Halfords battery was bigger but the battery tray was large enough to accommodate it and had a second captive nut in the larger position. Original battery was 59 ah but Halfords one is 70 ah.

After a run the battery temperature is 30 deg C with ambient temperature of 8 deg C.

Bit of a nightmare setting up the electrical systems again but done.

Everything now OK I hope?

Thanks

 

[Towpack]

So, another big for good old low tech. All that grief from just a flat battery. At least with the old stuff you just throw in a new battery and go! Glad you got it sorted.

 

[StarCruiser]

Pop your multimeter, set to Volts, across the battery just after starting Frank. If you mean the voltmeter is showing 12.7 volts that’s no good to charge the battery. Modern cars cut the alternator out and can vary it’s power via the ECU so test it just after starting. It’s a good bet to have the alternator cut out feature disabled as it kills batteries by only half charging them.

If it’s a wet lead acid conventional battery it should be getting 14.4v and if it’s an AGM 14.7v.

 

[frank rabbets]

14.85 volts just after starting so it looks like a trip to vw just to check things out.

Thanks