Model A Electrical Fire

[MALAK]

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This kinda makes the point that a battery cutoff switch can be an important safeguard.

I agree. This picture proves the point that these things can and DO happen. Regardless of how rare I wouldn't want this to happen to my car. Although it's impossible to tell from the pic what condition led to the fire i.e. short circuit, loose connection, ignition left on and coil overheat etc. Personally I use a 60A fuse that feeds a power distribution block with individual fuses for each circuit. This allows me to use a fuse size appropriate for each circuit. Something else to consider: What happens in an accident? The possibility of an electrical fire greatly increases on a non-fused system. I'd hate to get in an accident in my A but to get in an accident and have the car catch fire (and possibly be trapped in it) when a 50¢ fuse could have prevented it is not something I'm not willing to risk. Attached is an excerpt of my electrical system. While it's more complicated than most here like I have peace of mind that a fault in any circuit will not disable the car and the possibility of a fire is greatly reduced.

 

[Tom Wesenberg]

And yet I was always taught to NEVER connect near a battery as the arc could cause an explosion. Seems like that disconnect could be a very dangerous item under the right conditions?

Yep, I've had a couple batteries blow up when I failed to uplug the battery charger first.

 

[1965 Mustang]

I have a cut off switch on the positive (grounded) side of my battery.
I turn off the entire electrical system when I am not using my A or away for more than a few minutes.
I have done this for years on all my old cars. (I once had the front seat catch on fire on my 1940 DeSoto.)

The switches are less than $30 and good insurance.

I also always carry a fire extinguisher in all my cars.

 

[Y-Blockhead]

And yet I was always taught to NEVER connect near a battery as the arc could cause an explosion. Seems like that disconnect could be a very dangerous item under the right conditions?

There should not be an arc when closing the disconnect switch unless there was a high draw when it was opened (doubtful), or a short 'occurred' while the car was just sitting there.

If you had that high of a draw to cause an arc while the car was parked the battery would soon be dead.

 

[Barry B./ Ma.]

Kurt brought up a good point. Since the lights/horn power is taken from the cutout output terminal, the generator output will still be going into the lights and horn circuits. If I was to add a fuse to my Model A I'd add a 20 amp fuse between the cutout output terminal and the lights/horn terminal.

That's what I did on mine, I took off the fuse at the starter and put a 30 amp in line fuse at the light /horn output wire from the cutout as the lights are the most likely source for shorts as they were in my case. I would like to fuse the ignition but can't determine the best spot for the fuse, maybe a 20 amp in the light circuit in line and a 30 amp at the starter.

 

[MrTube]

There should not be an arc when closing the disconnect switch unless there was a high draw when it was opened (doubtful), or a short 'occurred' while the car was just sitting there.

If you had that high of a draw to cause an arc while the car was parked the battery would soon be dead.

If there will never be an arc when closing the disconnect switch then there is no reason to have one. The reason for installing one is for the rare situation that something shorts in which case when you close it you will have an arc. Also, according to your logic there is never a need for a disconnect or fuses if the car is parked. I disagree.

Furthermore, for those who install electronics or have an alternator on their "A" there likely will be a small arc when connecting and disconnecting.

I would say besides that, my opinion on the subject is if I don't trust my wiring and its connections enough to leave the battery connected when not in use, then the wiring and connections need to be redone. Besides having good wiring installed away from sharp and hot objects I would also insist on multiple fuses as others have said. If a wire will burn up without the fuse blowing then the fuse is the wrong size.

I've been using antiques of all types for many years and I would never use one I was afraid to leave plugged in when I go to bed. If I have any doubt it gets rewired. I'm currently rewiring a monitor top fridge because like everything else, if you can't trust it, it shouldn't be in use.

Just my opinion.

 

[MrTube]

Yep, I've had a couple batteries blow up when I failed to uplug the battery charger first.

What happened Tom? Were you ok?

 

[Tom Wesenberg]

What happened Tom? Were you ok?

I was OK, but my ears were ringing for a couple days. The battery was blown to pieces. This one happened about 12 years ago. The first one to blow was when I was 18 and working at a service station. I lifted off the battery charger cable and the spark ignited the gases. Luckily just the push on caps blew out. They hit the hood and shattered. The bad thing is the customer was standing there watching.

A third battery blew when I was asleep. I had a 1 amp charger on an old battery setting on the garage floor in front of my dad's Olds. When I went out to the garage the next day all I could find is a bunch of acid spots on my dad's Olds and part of the bottom of the battery case. I never did find enough of the battery to haul in for scrap.

One night I left a 3 amp charger on my Dakota pickup radiator. When I came out in the morning I found the charger burned up, but luckily it wasn't next to anything that would catch on fire, so the fire was confined to the charger.

This is why I never like to leave a battery on a charger unattened.