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I promised Gary I would take some Amperage readings on my 54 Cavalier.

We were talking about 6 Volt air conditioning.

New old-stock Delco-Remy regulator of proper size; newly rebuilt generator.

Measured with a 50 Amp shunt in series with the generator output terminal and the regulator input.

The 6 Volt system is rated at 45 Amps per the service manual.

With the car at normal warm idle in the driveway:
The engine draw alone is about 6 Amps, this would include the dash stuff.
The Radio is 5 Amps.
The front heater fan on high is 12 Amps.
The Headlights on low beam is 17 Amps.

The generator regulates the voltage at 7.3 volts measured at the battery terminals. Ad idle it keeps up with lights and radio or radio and heater fan but three things pull it down to 6.5 volts until the engine is slightly revved then it pops right up to 7.3V.

With everything on and the car cruising down the road the total draw is 41 Amps (one heater fan only).

After a long stop-light the generator max's out at 50 Amps as the battery voltage climbs back to 7.3V.

Jim

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Jim already has AC in his Packard that runs off of a separate 12 volt system but he would like to convert to a fully functional 6 volt system and eleminate the need for the extra equipment under the hood. I think he and I are about the only ones who keep kicking the idea around but I also know that Harold (HH56) has contributed some solid theories on the possibility as well as some great information supporting them. It's not just Packard people who want to pursue 6 volt AC but quite a few owners of other makes continue to inquire about it. It seems that I recall HH stating that a Sanden Rep. provided an unofficial approval to run one of their clutches off of a 6 volt system as long as it could provide and maintain a steady 7.3 volts. I believe this can be accomplished using a 6 volt Gener-nator but not sure Bill's current Generator will support it.

It seems that I recall HH stating that a Sanden Rep. provided an unofficial approval to run one of their clutches off of a 6 volt system as long as it could provide and maintain a steady 7.3 volts.


It was actually Dwight Heinmuller who had mentioned the unofficial sanction. He had received the information from his rep and since has been running a Sanden with his factory 6v trunk unit. Not sure how long now but apparently quite some time and without difficulty. Somewhere on site in one of those AC discussions of a year or so past there is a post where Dwight mentions the compressor detail and possibly included a photo.

There is at least one and possibly two other cars doing similar with a hang on unit. Don't know any direct info as to how the blowers were handled or believe anyone involved has posted on site with any details. That info was word of mouth.

At the risk of over simplification; why not just engage a compressor clutch at 12v and use a torque wrench to see what it takes to slip. Then try it at 6v-7v, and see how much holding capacity you have lost. Not very scientific, but should be "real world" useful. I may be missing the point of this discussion. Just my thoughts.

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Probably not a bad idea to get some pertinent data. Unfortunately, even with good numbers that may not be enough for some to feel comfortable trying it since the label would still say 12v.

The bigger issue is the blower motor(s). Only 6v motor that seems to be more or less readily available is a single shaft heater motor. Generally those are smaller in every aspect than motors used for AC.

The classic old time looking dual shaft hang ons would probably be out but there are some single motor single shaft hang ons which might be an easy conversion -- if the smaller motor is adequate. Those I can think of would look a bit modern and maybe out of place in our old cars so that might be an issue.

Without knowing the particulars of any already proven unit or how successful or problematic others have had in adapting, without a very friendly AC shop it will take $$ in parts, guess work & experimentation for one of us to find the solution and document it.

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Exactly HH, and the various challenges are what Bill and I have been discussing. As I stated above, Bill's current system is a combination 6/12 volts, the entire car still operates on the original 6 volt system while the AC operates on a small independent 12 volt system that Bill says is borderline capable of meeting the demand that it requires to operate. It has a small 12 volt alternator mounted below the compressor behind the transmission cooler and a compact 12 volt Battery that sits in the same tray as the 6 volt battery. Other than having to make sure the single drive belt is correctly tensioned, Bill has stated that the AC operates quite well but he would prefer
to figure out a way to run his AC on 6 volts so he can eliminate the separate 12 volt system.

What kind of "small 12v alernator" is used?????? Note that the Suzuki Samurai (Geo Metro) alternator is very small and powered a full modern vehicle. About $80.

The small battery mite be a problem too. Probably a motorcycle or lawn mower battery. They are notiously short life (2 years) and tend to loose efficiency/ charging capability after about 1 year. Doesn't matter how good or how bad an alternator is if the battery does not take/hold a charge.

The problem with 12v accessories/ignition running off of 6v is that there is little to no margin of discharge below the 6v threshold to maintane operation.

It all has to dod with percentages.

Loose 2v efficiencey of a 12v system leaves 84%.
Loose 2v of a 6volt system leaves only 66%.

Most electrical items will operate (to some degree of ) satisfaction at about 75% of required voltage. But below that becomes very unreliable.

You could also use a 12/6 battery or 2 6V batts in series - 6 V for everything except for the AC. It would require a 12V charging system.

The add-on A/C was already installed in my car when I bought it about a year ago. Unfortunately I can't identify the 12V alternator without removing the mounting bracket, which will be difficult. The mounting bracket is homemade but nicely done. It is tucked in tight above the transmission cooler and mostly hidden by the bracket. I can't see any markings or labels. I say Japanese made. The man who built this A/C is apparently retired and not able to help. He told me he got the alternator from a generator shop and it fit the space but that was all he knew.

The alternator is quite small and is probably a permanent magnet type and it just barely runs the A/C.

My car is 6 Volt positive ground and the 12 Volt system is negative ground and it does not connect with the 6 Volt system.

I have a relay that is operated by the ignition switch which disconnects the 12 Volt battery when the switch is off. Otherwise both the alternator and the A/C would run down the 12 Volt battery. The alternator apparently doesn't have a diode in the output or a cutout. It does provide a charge light which is mounted on a small panel under the dash with a toggle switch that Also operates my battery relay. There is also a fuse in the battery circuit.

When I turn on the ignition switch and start the engine the A/C can come on and be fully operational .

The 12 Volt battery is a AGM type made for an RV or snowmobile. It is always getting a regulated charge voltage when the car is running regardless of the A/C running.

The problems are as follows:
Requires too much tension on the belt.
One BX type fan belt under too much load in my opinion.
Not enough wrap around the fan pulley "in my opinion".

Requires an idler which puts a slight reverse bend a BX type belt which has caused several to shed teeth.

The Sanden Compressor pulley is built for two belts.

Just getting rid of a couple of Amps of Compressor would help this system out.
I can easily try the clutch on 6 volts time permitting.

Jim

You can run a 6V system on an 8V battery if you adjust the voltage regulator up from 7.2 to 9.5 volts.

No other changes required.

So, if a 12V clutch will work on under 8V this could be the answer.

+ vs - ground,the only things I know of that are voltage sensitive are the coil and the radio vibrator. The vibrator can be replaced with a - ground electronic one, and the wires on the coil can be reversed. The generator can be reversed by polarizing.