Packard Forum Index » Post-War (1946-54)

Saw this interesting battery installation at a car show on Sunday. Thought some here would like to view it. JWL

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Well done! Ernie

I wonder if that is the car with 2 6v Optimas configured in parallel but can also go in series. I forget where I read a description of what was done for that arrangement -- maybe the PAC forum. There is a jumper that looks like it may be series but also 2 wires appearing to come off the same place and go somewere else. If it has AC wonder if the whole car is 12v.

Is that the end of the compressor or an alternator? Did you happen to get any photos showing the AC bracket?

The owner was elswhere. The device peeking out is the alternator. I did not get a photo of the compressor and its mounting. I think you may be correct about a 6V-12V connection. JWL

I can't resist!

This appears to be a 'center tapped' 12 volt system. The two smaller gauge wires would be connected to the 6 volt center tab. This type of electrical system allows for dual voltage, common polarity, power. I suspect the starter is connected to 12 volts, as is the AC. The rest of the car remains 6 volt. I equally suspect the polarity has been switched to negative ground ( I surely would and then again I would also power the ignition system with 12 volts).

The only piece of electrical equipment that is polarity sensitive is the radio ( I think ). Given that the original radio may or may not work, cost of vacuum tubes, and 12 volt negative ground power is now readily available, a modern radio could be installed somewhere in the car. The power to the OEM radio is easily disconnected.

I don't have any experience with the overdrive solenoid, but give that those small automotive relays work with either polarity at the pull-in coil, I would think the OD solenoid would work OK.

I've been told that heater blower motors will reverse direction when the polarity is swapped. The good news is that air will still flow in the correct direction, albeit at a reduced flow rate. The blower wheel vanes had been optimized assuming a known direction of rotation, and swapping polarity just blew all of that science into the water and the flow rate goes down.

If the starter still has 6 volt field pole windings that's a bit of a gamble. Except for a 6 volt to 12 volt conversion on an old VW bug years ago I would change, or modify, to a 12 volt rated starter. The Bendix drive life will be far less at the elevated starter torque that results from the higher voltage. I've also heard that the 'nose' of the starter housing may be a weak link, but fortunately have no firsthand experience breaking starter housings. The really good news is the starter will spin in the correct direction independent of the polarity. I'm still scratching my head over that fact.

This isn't a complete change-over to 12 volts, so the good news is that none of the bulbs need changing.

The generator idiot light (if so equipped) may be a casualty unless the alternator has the provision for that feature. Many Delco 10 or 12-SI units ( the alternator in the photo looks like a later model ) will have a location to connect the idiot light. The current to 'light the light' also excites the alternator and the unit will produce full voltage at a lower speed. Sometimes these older cars have a smaller crank pulley diameter and need a little more idle speed, or a smaller than normal alternator pulley to have full voltage at or near idle speed. If the car has an ammeter I'll have to go get a sheet of paper and figure-out how to wire that . . . it could also be a casualty. The two wires from the center tap could be just to buck the ammeter so it stays in the middle all of the time. A voltmeter would let you know if the full system voltage is about 14 vdc (everything is OK), or 12 vdc (something is broken) in either case. I'm working on a Zener driving a LED circuit as a poor man's voltmeter.

You can buy many 12 volt batteries center tapped for dual voltage, but I don't believe I've ever run across one of the 19 inch long, 4 inch wide units center tapped. Two six volt batteries won't push the cost over the top . . . especially considering how much expense is avoided by keeping most of the car 6 volts.

I think I would have built a bit of a cover for batteries and slap a 'Willard' decal on it to hide a bit of the complexity. I also paint the tops of the Optima batteries semi-gloss black, and take the 'stickers' off.

The AC compressor appears to be mounted where the generator normally is mounted.

dp

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Modern permanent magnet motors will reverse direction with polarity but the heater motors Packard used have a separate field coil and armature which are permanently connected together internally. Unlike the permanent magnet motors which have the N-S relation of the field always the same, if the polarity is swapped the armature reverses direction because only its N-S changes and changes the relationship between field and armature. On the older Packard motors because the windings are connected together, the field coil swaps N-S as does the armature so the N-S relation between the two stays the same and the motor keeps running in the same direction. Same applies with the starter motor.

Packard used two methods to reverse their motors One was to bring field and armature out as separate leads and change orientation in a switch. That was the method used in the older Deluxe heaters which reversed for heat or defrost. The other motors -- antenna, window, TL compensator etc -- have two separate opposite wound field windings. The windings were connected together at one end which was also connected to the armature and ground was applied to the other side of the armature. In operation one winding was powered and for the opposite direction, the other oppositely wound winding got the power. Being wound differently caused the field N-S relationship to change but because the armature always had power to the same place its NS field stayed the same.

DC voltage is not rocket science. It's been around for over two centuries.
I've routinely run 24 Vs off two 12 v batteries on my boats going on 30 years. So they same applies for 6V. You just have to match wiring to the charging system.
Separate grounds help, but that's a no brainer in fiberglass.
Looks like two red top 6V Optimas to me with a fabricated hold down. Takes a little knowledge and wiring outside the factory stuff.
Whatever happened to adapt, improvise, and overcome?

So can the original 6v generator charge two 6v batteries? Then you could leave all of the car 6v, but also run your aftermarket 12V AC across two batteries? I think I need to draw out a wire diagram. LOL

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If you can figure that out a lot of people wanting to add AC without doing a full conversion will be in your debt.

It is easy enough to charge them by putting the batteries in parallel when the AC is off and letting the generator charge both but as soon as you turn AC on and the batteries need to go in series and supply the AC then you need to disconnect the aux battery from the generator to prevent a short and any 12v feedback to the rest of the car. When that is done the isolated battery will not charge and depending on how long AC is on and how much load is being pulled the isolated battery can get seriously discharged. If the two batteries are not somewhat close in their discharge states when placed back in parallel some charging issues can arise.

Just my two cents!
After looking at the picture, I would think he is using a 12 volt Alternator to charge the two 6 volt batteries connected in series, because 6 volt + 6 volt = 12 Volts, and by tapping off the center jumper he would get 6 volts from there to ground. Also smaller size cables since he's using 12 volt.
Wes

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