Dead 6V battery, 12V jump start with pos and neg wrong

D

DirtyDuck

Junior Member
Just picked up our 31 pickup - haha - and brought it home on the trailer. It started right away on the trailer, but then I was a bit shy on the clutch and stalled the engine.
As I have no experience with the A at all, the 2nd start attempt failed. I might have had to much choke and/or throttle, so obviously flooded the engine.
I kept trying to start but eventually the battery was empty.

I don't have a 6V charger yet and no 6V spare battery, so I tried to jump start using a 12V battery with positive on the block and negative on the starter main wire as I remembered to have read this somewhere here. Result was that I shorted my 12V battery (and most likely killed many more things), since unfortunately I didn't actually know if I have positive or negative ground... :(

All electrics in the car seem to be dead, the 6V battery only has 2.1V left. I didn't have time yet to check everything, will do as soon as the 6V charger and a replacement battery arrives, but would appreciate to get any hint on what I possibly could have damaged. I.e., how much of an idiot am I?
Also, how can I determine if I have positive or negative ground?

Thanks.
 
'A's' are positive ground originally. If yours is 6 volt with a generator it probably is + ground. If it has an alternator it could be either + or - ground.

The way to check is to remove the floor board cover n front of the front seat and look at the battery terminals. The rear terminal is usually the + and its cable attaches to the vehicles frame. The front terminal cable goes to the starter.

So it sounds as though you connected the jumper battery correctly. Was it connected to another vehicle ? or by itself ?
 
All original Model A electrical systems are all positive ground.

To check the polarity, remove the front carpet or rubber mat on the drivers side and there should be a removable metal cutout plate on the floorboard where you would rest your feet. Pull the cover up and look and see if the previous owner had installed the assumed 6 volt battery as a positive ground. ( + side to the chassis )

To remove and replace the Battery : Remove the screws attaching the floorboards and remove the floorboard to gain access to the battery. Before installing the new battery, clean the cables, both ends, especially where the positive grounds to the chassis.

If your car has a fuse block installed on the top of the starter, check the fuse. If blown, replace with a 25 amp fuse. Good luck and enjoy the new truck.
 
You can jump with a 12v battery-but not for long. Dad and I used to do it when the 6v was dead. Just line the batteries up in parallel and watch her spin right up! But when she fires disconnect the 12v or you will fry things. Where are you located? What about Pics? Remember to join a local club and NEVER throw anything away.

Mike
 
You are more apt to damage the 12 volt car than the 6 volt car when jump starting as mentioned.

Assuming you have a positive ground Model A and you connected as described, the worst you could do is damage the coil on the Model A. If the Model A is not positive ground, and you connected as described, then it can be a whole lot worse.
 
And other thing is make sure you don't touch the brake pedal or have any lights on SS they will burn out immediately. Wayne
 
What makes you think you need a new battery? It probably just needs to be charged. If you did put it on wrong, it must have sparked like crazy. You should only get a very light spark when you make your final connection. You may have touched ground when you were hooking up the battery. I think you will find that you are OK. jack
 
Thanks everyone for your replies. I've checked the wiring, it is positive ground, so a bit more relaxed now. I got a 6V charger from a friend, it shows correct charging, so will know more tomorrow.
I didn't touch brake pedal or have any lights on. After I connected the charger, I tested all lights and they all work.
However, I still wonder why the jump start didn't work. There was no big spark, just the one you encounter when jump starting any vehicle. The battery was not connected to a car, it was one of the spares of my F350 truck and was recharged two days ago.
 
Patrick L. said:
'A's' are positive ground originally. If yours is 6 volt with a generator it probably is + ground. If it has an alternator it could be either + or - ground.

The way to check is to remove the floor board cover n front of the front seat and look at the battery terminals. The rear terminal is usually the + and its cable attaches to the vehicles frame. The front terminal cable goes to the starter.

So it sounds as though you connected the jumper battery correctly. Was it connected to another vehicle ? or by itself ?
Click to expand...
With the number of changes that have been made over the years I would look to see which batter post is larger, that should be the positive. Hopefully it is located at the rear of the battery and a short ground strap goes to the frame. If you need to replace the cable that goes to the starter switch be sure to get one designed for 6 volts (they are larger diameter). Thew guys in modern parts stores don't even know there is a difference, if they have one that is the correct length they will sell it to you. You may need to buy one from a Model A parts supplier or have one made by a welding supply shop. Don't feel bad, we all had start somewhere.

Charlie Stephens
 
In my case the rear terminal is (-), but goes to the starter, the front terminal is (+) and goes to the ground strap (kind of copper mesh flat wire). I have no clue why the previous owner did it this way instead of turning the battery 180 degrees and use shorter wires, but it's definitively a positive ground.
 
If the motor turns over, but doesn't start, it is possible that the ignition coil is damaged (open circuit).

If the starter does not turn over, then that is likely damaged.

Not many other possibilities, assuming it ran until it died only from too much clutch.
 
A Couple of points; The plus/positive terminal is usually just a tad bigger in diameter than the the negative terminal. This is usually about 1/16".
Secondly, look at your ammeter. If it works backwards then your polarity is backwards.
Terry
 
It's possible the 6V battery is on it's way out or you may have a dirty connection somewhere in the wiring. Dirty connections will draw a lot more power from a battery.
 
Don't choke it for more than three revolutions of the engine. If you do flood the engine, hold the throttle wide open to clear it while you're cranking. Also, remember to retard the spark (lever up) after each run and advance it immediately after it starts (Lever down)
Terry
 
As you found out, the battery is stamped + and - and the + post is larger diameter.

You can charge a 6 volt battery with a 12 volt charger IF you connect a 12 volt light bulb is series between one of the charger cables and battery post. If you use a small taillight bulb the charger might be 1 amp or less, but if you use a headlamp bulb then the charge might be 5 to 10 amps. A long slow charge is better for the battery than a heavy quick charge.
 
DirtyDuck said:
In my case the rear terminal is (-), but goes to the starter, the front terminal is (+) and goes to the ground strap (kind of copper mesh flat wire). I have no clue why the previous owner did it this way instead of turning the battery 180 degrees and use shorter wires, but it's definitively a positive ground.
Click to expand...





Good. I knew you knew the terminals were marked. Hopefully all will be well.

There are some that insist an updraft system cannot flood, but, you appear to have found out that they can.

So once everything is dried out and the battery charged all should be well.
Just in case you may want to pull at least one sparkler to make sure it is dry and not fuel bridged. Usually when an engine is badly flooded I remove all the sparklers, dry them, spin the engine over a few revs and squirt a bit of oil in each hole.

If the engine starts, good. If not, let us know.
If you're not quite sure of the starting procedure, let us know.
We'll get this monster running.
 
DirtyDuck said:
Just picked up our 31 pickup - haha - and brought it home on the trailer. It started right away on the trailer, but then I was a bit shy on the clutch and stalled the engine.
As I have no experience with the A at all, the 2nd start attempt failed. I might have had to much choke and/or throttle, so obviously flooded the engine.
I kept trying to start but eventually the battery was empty.

I don't have a 6V charger yet and no 6V spare battery, so I tried to jump start using a 12V battery with positive on the block and negative on the starter main wire as I remembered to have read this somewhere here. Result was that I shorted my 12V battery (and most likely killed many more things), since unfortunately I didn't actually know if I have positive or negative ground... :(

All electrics in the car seem to be dead, the 6V battery only has 2.1V left. I didn't have time yet to check everything, will do as soon as the 6V charger and a replacement battery arrives, but would appreciate to get any hint on what I possibly could have damaged. I.e., how much of an idiot am I?
Also, how can I determine if I have positive or negative ground?

Thanks.
Click to expand...

Do you know how to start a Model A? Not like modern cars.
With cold motor
1: open gas valve
2: retard spark
3: turn choke/mixture rod clockwise to close
4: open choke rod 1 turn
5: turn on ignition
6: hit starter
7: immediately pull out choke
8: immediately push choke all the way in

If it doesn't start the first time, something is wrong

With hot motor pull out choke may not be necessary.
 
Thanks mrtexas. I followed the starting procedure you described at the seller where we pickup up the car and again on the trailer when we wanted to unload it. In both cases it started right away, so the problem really seemed to be that I flooded the engine when I started it the 2nd time on the trailer.
Battery was charged overnight (I'm in CET timezone), amps look good, so will give it a try after my morning coffee.
 
Status update:
The 6V battery didn't charge properly, had the charger on all night and it still showed 6 Amps charging current this morning. After disconnecting, the battery still shows only about 3.8V.
Took the starter out, disassembled it, cleaned everything and assembled it. Works fine on a 12V battery.
Tried again to jump start with a 12V and this time at least the starter turns the engine, but it won't start. I was taking out a spark plug to check, but no spark.

My next steps will be checking the ignition coil and then the generator. Any help is appreciated.

Thanks!
 
OK, had a blown fuse, obviously installed by the previous owner between starter main wire and the wire that goes to the main terminal at the firewall in the harness. Replaced it, but still no spark. Then figured out that the wire at the positive terminal of the ignition coil was loose.
Now turns and has spark, but still doesn't start, so will wait for the new battery to arrive tomorrow and try again.

Thanks to everyone for all the help. This is like drinking from a fire hose for me, but fore sure helpful!
 
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