We assume this car is negative ground ? and this is a 12 volt car?

Didn't see the year mentioned.

I have a 54 Cavalier which is 6 volt positive ground. my add on A/C has its own small alternator for negative ground 12 volt.

Using an Optima 6 volt battery, I have a small 12 volt battery on the battery shelf for the A/C.

All modifications are reversible.

Jim

My take on this question:

When jumping a 6 volt car, modern light weight, 12 volt jumper cables probably won't convey enough Amps to ctank the dead car.

Connect the cables + to +, - to - directly battery to battery and verify the polarity before connecting the final cable and be certain the jumper cables have the same color clamp on the same wire at both ends.

If you are using light duty jumper cables watch the temperature and don't burn a good paint job with a molten hot cable.

If the dead battery will take a charge and hold it, I see no problem of having the engine running on the good car as the generator is regulated and won't see any more load than normal.

The good battery will deliver 6 volts at the rated cranking Amps (1000 CCA?) and go lower if the dead battery is accepting the charge.

Sometimes a long dead battery will develope an internal short in one or more cells you should watch for this

You should be watchful of causing sparks anywhere near vented liquid filled car batteries as hydrogen is produced while charging and it can explode.

Here in Arizona where the temperature is 116 outside a battery will go from working fine to totally dead after a stop at the grocery store as I found out last sunday, with no warning.

Jim

I will have to look for the sticker on the Optima and see if there is a decodable date code.

I won't argue the voltage the third brush generator will go up to 70 to 120 V could be the number.

I believe the generator fails due to heavy arcing at the commutator which gets hot enough to melt out the solder.

I know the Ford T service bulletins say short it out with a piece of wire on the generator side of the cutout (battery disconnected) and since having done that a few times since I rebuilt the generator in 1968 I have only had to replace batteries (and headlight bulbs). I have mine set at 12 Amps on the model T and I usually drive with the headlights on.

The Field is internally connected to the third brush and not reachable from the outside of the generator which is gear driven and not an easy thing to remove and then drive the car.

These Absorbed Glass Mat batteries are made with the electrolyte absorbed in a fiberglass mat material and then the plates and mat are all rolled together. As the mat dries up due to years of use and heat I believe there is arcing between the plates and eventually the battery destroys itself although nothing leaks out ever.

They have a mechanism whereby the Hydrogen and Oxygen gas is made to recombine so these batteries don't dissipate gas or normally go over pressure.

The 6 volt Optima is rated at almost 1000 cranking Amps. I do not believe a 6 volt battery made to the original size and fit and capacity the Packard had originally is still available.

I have a small ATV size 12 volt battery along side the Optima 6 Volt that runs the add-on A/C with a special hold down bracket. I'm thinking of working up an FM to AM radio converter that can power up from the 12 volt system so I can gain a little variety as AZ only has about one AM radio station I can stand to listen to. The 12 volt system is all bolt-on and no permanent modifications are made to the car. Damn good load on the single fan belt however.

The battery that came new with my Harley Davidson Motorcycle in 2008 was as quirky after the first year as the Optima became in the Packard. I even took it into a dealer on warranty and they wouldn't replace the battery. Finally I bought a new one and presto no more starting problems.

The point I want to make here is these AGM batteries can fail and leave the poor motorist thinking starter, generator and last the battery.

Jim

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

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

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

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

I live in Phoenix AZ and the temperature has been over 110 degrees already this year and can go as high as 120 but 115 to 118 is not uncommon.

Most of us use refrigerated A/C; my 1600 square house has a 3.5 Ton split system.

The A/C systems are often package units which can operate as a heat pump or have a gas fired furnace as we can get into the 30's in the winter.

Some people use "Swamp Coolers" until the temp gets over 100 degrees or the humidity goes up in the Monsoon season We have two stage swamp coolers that work fairly well.

My 1954 Packard Cavalier has Add-On air conditioning which I am in the process of perfecting.

Jim

I live in Phoenix Arizona, it only hit about 102 today June 5.

I plan to leave my office in my 1954 Packard Cavalier with the air conditioning running, the AM radio tuned to the only listenable AM station, and the windows up.

My A/C is an underdash add-on with its own 12 system, the car is still 6 volt. It doesnt appear to add to the engine temperature.

The top of my car is a dark blue (Maridian Blue) and when the car is out in the sun it gets very hot inside. Fortunatly the office provides indoor parking.

Jim

Steve

Thanks, I deleted the first entry (I think) and re entered it with improved information.

My car came with all the original documentation including the original owner papers so I went to the local historical people and got the picture and info.

Jim