26 T battery trouble

[KCW]

Recently bought an awesome 26 T roadster pickup. The battery died after s little while and I replaced it. It has been working well for weeks but the electric starter has been getting weaker and weaker. Now the battery is dead again. I had someone add a kill switch to the battery and use it when I’m not driving the car. Therefore, I know it’s not draining the battery when it’s sitting.

Any ideas on what the problem is? The car has no magneto. Keep in mind, I’m new to owning a T and am pretty novice at my understanding. Without the magneto what is firing the sparks when I’m driving? Is it the battery? Also, is there a mechanism by which the battery is recharged when I am driving? Any help is much appreciated. Thanks in advance!

 

[rosenkranswa]

Since you have a new battery, it sounds like your generator isn't recharging the battery rather than a battery problem, so each time you start you drain the battery a little more and the charge doesn't get replaced. Eventually the battery is too weak to spin the engine.

If your car doesn't have a magneto, you must have a distributor type of ignition, either a period one or one of the newer versions, rather than the original buzz coils. Many T's have them and they're pretty reliable.

Key elements of the charging circuit are the battery, generator, and something called the cutout which switches the current flow to/from the generator to the battery for charging above a set RPM. There is either a set of points or a diode in the cutout which can go wrong and results in the generator not charging the battery. The other possibility is the generator is bad, but that's unlikely.

Get a voltmeter and start running down the charging circuit. I'll bet you find you have a bad cutout, but do the Dx first before you start replacing things. Get a copy of the "black bible" the Model T service manual which will help. Another book l use all the time is "The Model T Ford Owner" by Murray Fahnestock. Best thing though is to find and join a local club, have someone come look at it for you, and learn from them for the future.

 

[40 Deluxe]

All old cars like your T need far more maintenance than new cars. It's just the nature of the beast and is to be expected. Unless you know someone who is experienced with old cars and want to pay him to work on yours, you will have to get the books and some basic diagnostic tools. A basic volt/ohm meter is a necessity. Depending on your skill level, a night course at a local school or college may be helpful. They won't teach Model T repair but you can get a good understanding of automotive electrical systems, etc.

 

[Brian]

What does the ammeter indicate with engine running? Should show slight charge; around 5 amps is good. If it shows nil charge, with engine running, use a jumper from one side of the cutout to the other. If ammeter now shows a charge, the cutout is at fault. Remove jumper before switching off ignition! Report your findings back here....

 

[KCW]

Replaced my battery and got my car to start. I took some photos. Does anything jump out at anyone regarding why the battery isn’t recharging? Thanks so much in advance!

 

[J Franklin]

Can't see electrons so you will need to do some checking with a meter. You may have just bought a faulty battery.

 

[redmodelt]

A fully charged battery should run the coils for many many miles and your only real draw would be the starter. With everything off when you remove the battery cable do you get any sparks (take the ground wire off first) ? If so there is a short somewhere in the system or the cut out is not opening and the generator is trying to motor drawing down the battery when the engine is shut off.
WHAT does the amp meter read when the car is running?

 

[rosenkranswa]

So, KCN has buzz coils and not the distributor setup I thought he must have had since he said he didn't have a magneto. Wrong thinking on my part, I always associate no magneto with a distributor ignition, but not necessarily true.

Still must be something in the charging circuit though he's going to have to run down, and as was said, you can't see electrons so will have to do some tests. If everything is working, shouldn't he see a 10amp + charge on the ampmeter with the engine at a high idle, falling to 0 with maybe some flickering at low idle, and 0 with the engine off?

A negative charge reading at rest would indicate a short, no positive reading at high idle would indicate the cutout isn't opening? I guess that's assuming the ampmeter itself is OK.

 

[redmodelt]

Yes you can coils off the battery, the ramp up time is a little slower but they work fine.
Once again I am going to suggest getting a copy of the Ford Service Manual and or a copy of the Owners Manual. Both can be gotten at any of the T parts suppliers. Like any hobby there are terms and descriptions that apply and people understand and both will give you a good understanding of your car.
You have a magneto, the red wire to the terminal on the hogs head is connected to it. It's built in as part of the flywheel not on the outside.
So if you start the car with the key turned to "BATT" what happens when you turn the key "MAG"?

 

[Royce P]

Take a photo of the amp meter while the car is going 25 MPH.

Or just tell us what it says.

 

[tmodelman]

Just adding a comment on 'car has no magneto' as I spy the red wires are going from the mag pickup on the trans to the switch red mag wire at the firewall junction block. Your mag could work, have you switched to MAG with the ignition key?

The comments to check output of the generator is correct to have the battery get re-charged. Sometimes simple thing like loose connection of the yellow/black tracer wires at the junction block can cause stoppage of current, or the generator cut-out could be the issue and its stuck and current flow is being pulled from the battery at rest.