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I drive my 1954 Cavalier regularly

6 Volt system.

Recently the starter cranks slowly the first couple of compression strokes and then comes up to normal speed.

Usually the engine starts almost instantly.

The generator is charging to about 8 Volts, I have one of those Optima 6 volt Battery's which is probably more than several years old.

With an accurate meter at the battery the slow crank pulls the 6 volts down to 3.5 to 4.0 then it goes up to 5.0 something and then cranks at the normal speed.

I use battery cables (I made) that are very heavy gauge copper wire and I verified almost no voltage drop on the starter cables to the starter.

I popped the band off of the starter and the brush's and commutator look OK, no sign of arcing, the armature moves slightly toward the back when its cranking but I can't feel side play in any direction.

I drive in Phoenix AZ and the temperature is in the 110 range, the car starts quicker when cold (95 degrees than when hot (110).

Usually the starter cranks quite vigorously.

Jim

There are other possibilities like a bad ground just for example but your symptom is consistent with advanced ignition timing. I'd advise checking the timing before devling into anything else.

After Stressing that I may need to rebuild a starter I determined the problem is the battery.

My car was using one of those 6 volt Optima Absorbent Glass Mat (AGM) 6 volt batteries which normally cranked the car quite well.

The AGM batteries seem to fail differently than the old regular liquid filled car batteries.

I had the same problem with an AGM battery on my Harley from the day it was new and finally in desperation I bought a new one and no problem since.

I temporarily removed the 6 volt battery from my Model T Ford and dropped it in the Packard and it now cranks at light speed.

Jim

Jim

You used "Model T Ford" and "light speed " in the same sentence.

Good job !!!

Regards


John Harley

The Model T Ford doesn't go real fast but it goes real steady :)

And you don't need a battery to start it.

You do need to short the generator output terminal to ground (car frame) if you run without a battery; lets see if that raises questions

Jim

lets see if that raises questions

Been there, learned my lesson.

You could also just open (disconnect) the field terminal to get the same result, no?

Quote:

How old was your AGM battery when it failed?

Is that the situation where without a battery the voltage goes way up?

I'll confess to not being up on early third brush oddities so will ask one of the questions -- if you ground the output, what prevents that direct connection to ground from doing damage somewhere in the generator proper -- or without a specific load, does the cutout not operate or close to allow output.

I thot model T fords had a flywheel magneto.

Knowing I caused trouble here I will further comment.

The Optima brand AGM battery could be more than a couple of years old. The date it was installed was not marked and I have owned the car with the battery a little less than a year. This AGM battery is about half the size of the 6 volt battery I pulled from the model T. The original Packard 6 volt battery was much larger but I'm not sure there are choices these days.

The good part is the AGM leaves room on the battery shelf for the small 12 volt battery that runs the air conditioning.

I believe this Optima is rated at over 900 Amp Hours?

I also replaced battery cables with very heavy wire that is very flexible and I have the braded copper for the + side to the motor as soon as I figure out where to attach it.

Here in Phoenix AZ where the temperature gets well into 115 is death on car batteries especially under the hood.

The discussion comes up regularly in both the Model T ford world as well as the Packard world about 6 volt vs 12 volt and understanding the charging systems.

The Model T Ford uses what is called "Third Brush" regulation and the generator is looking for a load of about 10 to 12 Amps. The 6 volt battery provides the load and keeps the voltage from rising above approximately 7 volts. The old 6 volt lamps usually say something like 6-7 V if you look closely at the bulb. If you turn on the lights the charge to the battery drops accordingly.

If the battery fails open-circuit the model T generator will put out 200 to 300 volts DC looking for a load and eventually burn itself up. If you short it to ground it won't generate at all but the most it could do is 10 Amps which is just fine with it. Last time I had a battery fail in the T, I turned on the headlights and then realized in a flash that I had destroyed both really hard to find headlight bulbs. The model T starts on the 6 volt battery but then you switch to MAG which generates 18 to 20 volts AC to run the ignition coils. This is why T coils don't work so well when used on 6 volts. The magneto is a series of coils placed near spinning magnets on the flywheel. Model T's had electric starter as an option.

The model T charging system at 6 volts, 10 Amps is able to generate 60 Watts of power.

I believe the Packard Generator is good for 40 Amps at 6 Volts which would be 240 Watts of Power.

Jim