Thread: Battery Meltdown - fukushima style

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.

Originally Posted by 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.

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.

Originally Posted by manic

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! '...

LOL sorry, but I laughed when I read that.

I think it's mostly because I owned a scalextric set and LOVED it. 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. 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