Battery Meltdown - fukushima style

[manic]

Pleased to report that the 200tdi made it up to Melrose and back to Melbourne without breaking down. But there was bound to be at least one problem along the way....

On the way back I started thinking of my old scalextric set and realised it was because I could smell electrical burn. A puff of smoke came out the side of my dash and out came the call 'FIRE! :eek:'... Pulled over and reached for the extinguisher but the smoke had stopped, a fuse had popped and done its job. It turned out to be the power wire for the interior dome light that runs up the windscreen pillar, it was caught up between the door and a bracket - road vibrations stripped the insulation.

Anyway we made safe and continued on to the jet wash. Chassis and engine bay was blasted out to remove salts after a beach run. Later that day I could smell burning plastic. Following the nose we looked under passenger seat - battery box. On inspection we found the starter battery to be smoking! The earth strap was HOT and the battery walls were almost too hot to touch. :o Emergency stations!

I grabbed the tool box and got the battery out as quickly as I could, fearful that it would explode and take out my eyes. I put it out in a field and saw that it was bulging at the seams and still smoking! I hooked up the aux battery in its place and detached all the auxiliary wiring. I drove to a local garage and had them check the alternator and current draw. All came back ok. We drove on home stopping a few times to monitor the battery temperature but we had no further issues.

On the drive back past the field with the boiling battery I went to check on it and it was still red hot.. I left it well alone and arranged for the local garage guy to pick it up the next day as it was still too volatile to move.

I'm still not sure exactly what caused the battery to go into melt down.

Possibly:
- the dome light short stressed the battery, setting it off.
- the jetwash caused another short and disconnecting the AUX wiring solved the problem.
- the jetwash stuffed the alternator which overcharged the battery

After this experience I would quite like a current draw monitor or battery temperature alarm.

To identify if there is a short I thought to measure resistance between the NEG and POS straps (detached from battery) - but I had no idea what sort of numbers I should be getting? Resistance was low.

Using a multimeter inline to measure current draw at various points might have helped me trace the area at fault but would probably kill the multimeter if over 10amps. The amount of heat in the earth strap would suggest a lot more than 10 amps was being chucked about.

I'm going to restore the whole seat/battery box area and renew the wiring, add cut off switches etc. etc. Don't want that happening again - I have burning fear.

Oh and thanks to the red disco1 driver who turned back to see if we needed any help. :cool:

[Felix]

Possibly the cells in the battery shorted together causing a dead short between positive and negative within the battery. Therefore, low resistance. So you can imagine if you just connected the positive battery lead to earth while the vehicle is running- that's the full alternator output going straight to earth! Your aux battery was probably not isolated either so it was more than likely contributing to the fault current.

Best way to check earth strap IMO is have it all connected up as you would normally, then check voltage drop between the negative terminal and the lug connected to the body. You should have a very very small voltage (0.00xV) if not zero.

Similarly, do the positive. Positive terminal to the starter terminal or alternator/both (however the truck is wired up). Should get a similar result (however if you're using long leads with your meter then take into account possible error from the resistance of the leads).

Bit difficult to diagnose electrical faults over the interwebz but just an idea.

[manic]

Possibly the cells in the battery shorted together causing a dead short between positive and negative within the battery. Therefore, low resistance. So you can imagine if you just connected the positive battery lead to earth while the vehicle is running- that's the full alternator output going straight to earth! Your aux battery was probably not isolated either so it was more than likely contributing to the fault current.

Best way to check earth strap IMO is have it all connected up as you would normally, then check voltage drop between the negative terminal and the lug connected to the body. You should have a very very small voltage (0.00xV) if not zero.

Similarly, do the positive. Positive terminal to the starter terminal or alternator/both (however the truck is wired up). Should get a similar result (however if you're using long leads with your meter then take into account possible error from the resistance of the leads).

Bit difficult to diagnose electrical faults over the interwebz but just an idea.

Yeah I thought it might be a battery fault considering it continued to smoke and generate heat after it was removed from the car. The battery was left in the car for long periods of storage in recent years. The past month it has not been able to hold its charge well and I often had it hooked up to a battery charger when parked in the garage. I was going to get a fancy new one but put off the expense... clearly a mistake.

I'll test the leads and improve the wiring set up before fitting a good brand battery. The meltdown battery was a cheap one and about 4 years old.

[Judo]

On the way back I started thinking of my old scalextric set and realised it was because I could smell electrical burn. A puff of smoke came out the side of my dash and out came the call 'FIRE! :eek:'...

LOL sorry, but I laughed when I read that. :wasntme:

I think it's mostly because I owned a scalextric set and LOVED it. :D Sorry about the fire hazard too!

My only story to contribute is the other day I had the battery disconnected in my County but needed to crank the engine over, so I screwed down the neg terminal as tight as I could by hand. Gave it a wiggle, but there was no movement, so I concluded that was good enough. Turned the key and BAM! FIREWORKS from the battery next to me. :twisted: Whoops! The nut and washer are now one item. The weld is quite substantial! haha In retrospect, it was always going to happen not tightening the terminal with a spanner, but oh well. hehe :)

[Greyfox]

Glad the old girl is alright.
I had a similar thing happen many years ago, I pulled the battery apart ( not recommend, hey I was young), and the plates had fused together in one mass.:censored:
Has anyone tried a gel battery?