Battery almost exploded

[mickofoz]

My Golf R-Line 7.5 was in for its 3rd service on the 27th of December last year. I asked the technician to check the Start-Stop system as the car would not turn off on a regular basis, tendency increasing. On the report it says nothing was found, all is well. Yesterday I noticed a foul smell in the car. When I got home I opened the bonnet to investigate when I saw the battery emitting steam and I could hear it boiling. I rang VW's emergency assist line who sent out a mobile technician. He ended up replacing the battery under warranty. The price of the battery if I had to pay for... $423. WOW!!! I will write a letter of complaint to the service manager at Mile End in South Australia. Not happy.

[gregozedobe]

My Golf R-Line 7.5 was in for its 3rd service on the 27th of December last year. I asked the technician to check the Start-Stop system as the car would not turn off on a regular basis, tendency increasing. On the report it says nothing was found, all is well. Yesterday I noticed a foul smell in the car. When I got home I opened the bonnet to investigate when I saw the battery emitting steam and I could hear it boiling. I rang VW's emergency assist line who sent out a mobile technician. He ended up replacing the battery under warranty. The price of the battery if I had to pay for... $423. WOW!!! I will write a letter of complaint to the service manager at Mile End in South Australia. Not happy.

I'd keep a very close eye on the voltage at the battery when the engine is running, as that sounds more like an over-charging fault rather than a dying battery. You don't want it to happen again (unless they also replaced something in the battery charging system, in which case you are probably OK.

From what I've read premature battery failures (can't hold a full charge) are way more frequent with MQB cars than overcharging.

[mickofoz]

He did test the voltage while the car was running and it all looked ok. Even the old battery still showed ok voltage so I must have just caught it in time. It looked and sounded like she was ready to blow though.

[tonymy01]

Sounds like there was a short circuit on the battery? I.e car electrical issue rather than battery, although i suppose a battery could fail internally to short if something from a plate broke off or distorted enough.
Anyway, if no issues with new battery maybe it was something internal to old battery after all.

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[Frachter]

We had a similar issue with our work cars.

Had 3 near new (2yr old) Colorado utes have their batteries fail in the exact same fashion you describe. 6 months later we got a recall letter stating there had been a defective batch of batteries shipped with new vehicles.

[Tuan]

What brand / model of battery please ?

[tigger73]

It actually sounds like someone either disconnected the battery temperature sensor and/or there was a faulty sensor that didn’t get picked up/fixed when the first battery got destroyed.

People will disconnect the sensor as a way to disable stop/start but this is not a good idea as you can boil your battery like the OP. Not saying this is what the OP did as a faulty sensor/connector will have the same result.


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[mickofoz]

It actually sounds like someone either disconnected the battery temperature sensor and/or there was a faulty sensor that didn’t get picked up/fixed when the first battery got destroyed.

People will disconnect the sensor as a way to disable stop/start but this is not a good idea as you can boil your battery like the OP. Not saying this is what the OP did as a faulty sensor/connector will have the same result.


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Nope, None of that. Just a faulty battery.

[syncro]

Nope, None of that. Just a faulty battery.

That's what it sounds like to me. Probably a plate collapsed and caused an internal short. It would not have exploded.

Hose out around the battery to make sure none of the vapor is left on the paint or metal as it could cause corrosion problems in years to come.

[Dan_3MPS]

Exactly the same thing happened with my 2018 Tiguan in January.

Roadside assist came out after the car wouldn't start, did a test and battery + alternator passed it. Told me to drive it for a bit to get the charge up.

Next day driving from Gold Coast back to Brisbane the battery cooked itself. Different roadside assist guy came out and replaced the battery straight away, said it was most probably an intermittent internal short that became permanent.

All done under warranty for me, new battery was AGM rather than EFB type.