Electrical Issues - 24 Volt, 1955 M38A1

[sahazzard]

Hi fellow A1 Owners, we bought an A1 in fairly good condition (bad brakes like everyone we have ever bought) and have been riding it around with no problems. A couple of days ago, my kids were driving it around in low in the yard, parked it turned it off, but then my 7 year old accidentally left the key on.

Obviously, it ran the batteries down. I realized it the next day, pulled the batteries charged them and put them back and can't get any power in the "on" key position. I get a test light on the batteries when they are all hooked up, but no power to the starter. I thought perhaps the key being left on had damaged the coil and points, but on inspection, everything looked fine. Any idea where to begin? I'm not well-versed on 24 volt systems. It's run perfectly until this event.

Thank you.

 

[G744]

It will test just like a 12-Volt system as far as checks go.

First, perhaps you got one battery wired in backwards? Makes for zero volts overall.

Then: Did you mash the starter pedal?

If it turns the engine, your problem is upstream from the tap-off on the starter terminal.

The flow is usually thru the 4-pin plug on the voltage regulator, thence on to the ignition switch.

One thing to know is the power is stopped if the regulator output cable is unplugged, as the jumper between all 4 pins is internal to the regulator.

See if that reveals the problem.

DG

 

[sahazzard]

It will test just like a 12-Volt system as far as checks go.

First, perhaps you got one battery wired in backwards? Makes for zero volts overall.

Then: Did you mash the starter pedal?

If it turns the engine, your problem is upstream from the tap-off on the starter terminal.

The flow is usually thru the 4-pin plug on the voltage regulator, thence on to the ignition switch.

One thing to know is the power is stopped if the regulator output cable is unplugged, as the jumper between all 4 pins is internal to the regulator.

See if that reveals the problem.

DG

Hey DG, thank you for taking the time to respond. The battery wiring issue could be the culprit - I noticed when I took out the batteries and put them on the charger that one of them had reversed polarity, which I have never seen before. So when I installed it, I wired it up according to the reversed polarity.

- + + - no power, then tried the other way, - + - + and no power. After that, I substituted a different battery with normal polarity and attempted to install it and got a huge arch when I touched the jumper cable to the negative terminal on the substituted battery. Then I quit and started seeking advice.

Another bit of info is that we have had intermittent trouble with the foot operated, tap-off starter terminal, but it eventually works if you find the sweet spot. So nothing has been touched electrically which is why the problem is so strange to me.

We have left keys on before on the 12v systems and just about every time it has fried the points and or coil - so I just figured we friend something, but I can't find any indication of damage anywhere.

 

[sahazzard]

It was a battery issue - changed them out with good batteries - all is well. Hard to believe - the batteries just checked out after going all the way down.

 

[dmetalmiki]

WOOOAHH, Do not re connect batteries at all untill,
A). You have checked the correct polarity of the batteries.
B). You take off the loaf of bread cover and check if the contact points are welded together.

When, ALL the points are free and OPEN,

****Correctly Connect ONE 12 Volt battery ( To _ and + terminals of the batteries ( Obviously minus the battery loop cable for 24 Volts.)). And check for arcing or a short. With a positive to negative connection THROUGH A HEADLIGHT BULB>.

IF the bulb lights HOLD IT FOR 5 SECONDS and then release it.

You may have reversed the polarity of the generator previously! .

Carrying out the above will REVERSE the (Incorrect Polarity) To the correct polarity Again.

****DISCONNECT THE GENERATOR BELTS BEFORE CARRYING OUT THE ABOVE.

Now with 24 volts CORRECTLY installed, Repeat the above, And the generator must turn in the correct direction of rotation. 5 SECONDS. AFTER YOU CLOSE THE CHARGING POINTS (the coil on the right looking down at the Loaf of Bread you standing with radiator to your right and seating to your left.

ALL THIS ACTION is NEGATED if your vehicle has the newer ELECTRONIC charging regulator fitted. ( It is probably 'goosed! (BOTH regulators are common with M series trucks and jeeps, and are 'interchangeable')).
Perhaps Transistor change needed.

Check with an electrician first, As this is just How i changed the polarity on my ww11 jeep my Packard and an 1937 Austin 10.
Good Luck..

 

[dmetalmiki]

The battery you have charged the incorrect way MUST now have the negative terminal sprayed RED and the the POSITIVE terminal BLUE.
Batteries charged back the 'Wrong way in polarity' Are (Usually!) fully usable and serviceable, ( ONCE! )MARKED CLEARLY of course!.
(Flattening the battery again then charging at the correct polarity destroys them!).