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Im still curious tho.
Disconnect the ground from bat one. Place a volt meter between ground post of bat one and the frame ( frame or wire used to simulate the frame). Read the voltage. I contend that it will be 12 v when clutxh is engaged.

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I know it is hard to believe but many still do not do e-mail. Maybe David can help get you in contact.

Super neat job locating the relay box and battery disconnect.

(o{}o)

Yeah, there are many people with em addreses but never use the email or only check email maybe once a week or once month at best.
Anymore, admitting to no email or no internet is about as popular as admitting to still using an outdoor shithouse. Alot people have an email addy for the sole purpose to not appear backward.

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Disconnecting bat 1 ground and there will be no reference to measure to. The meter will just become part of the circuit and could only measure current with any degree of accuracy. I'm not sure my meter could tolerate almost 3 amps on the voltage scale without self destructing. Any voltage measured at that point would depend on voltage drop across a resistance. Hopefully, with proper size wires or clean connections to frame there is virtually no resistance to be developed between the clutch and battery post.

Neat circuit Howard. It theory it an automatic version of a "Center Tap" 12v battery where it has 3 terminals. But instead of a 12v battery being tapped for 6v, it's two 6v's being bridged into a 12v when needed.

Slick.

I appreciate organized intelligent applications. Congratulations Howard!!

Thats trick Howard and very well configured. It acts like a mini relay station where the required voltage becomes available as demand calls for it except it only routes the charge voltage to the one battery when the clutch engages correct?
What type is the auxillary 6 volt battery Howard and is it going to be located under the hood?

Are you planning on using the stock Packard generator or switching to the higher output "gener-nator" type 6 volt alternator?

The large battery is charged all the time as per usual but the small one can only be charged when the clutch is not engaged. I am hoping the clutch cycle off or rest time will be enough to keep it at a reasonable level while AC is running. The small battery can fall quite a bit before the voltage it contributes is too low to do much. If the reports of those running on 6v is correct, it could fall to 0 volts and not be missed. Of course, that doesn't do the battery much good so we'll see how it works out or how long it lasts. When the AC is off or when car is off and parked then it should recharge back to the same potential as the main battery minus a few hundred millivolts because of the charge current limit resistor.

The battery is just a small sealed rechargeable 12 ah lead acid unit similar to McMasters 7448K34. I picked mine up locally. There are larger capacity units in roughly the same size package and if needed, can go with one of those or even parallel this one. Will try small cheap and simple first.

I am planning to install it on the firewall where I have the mockup shown. In doing so I added another relay in the module to disconnect AC when ign is off. That signal plus the starter signal can probably be grabbed off the starter switch on carb -- but will investigate that farther. Those two wires plus the run to compressor can be in a single loom. Another two wires will need to go into the passenger compt for the AC power and clutch signal so another loom thru firewall in one of the existing grommets. The power to the entire assy will come off the starter solenoid terminal with ground wherever convenient. Anyway, that's todays plan. It can change tomorrow.

Debating on the alternator but probably will try keeping the generator for awhile and see how it does. Downside to this experiment is it will be some time before my car is anywhere close to being ready to test. Until that happens I can't say with certainty something overlooked or negative will not show up.

Sorry HH, my bad...I mistook the battery photo for the module enclosure. Your design is darn close to being a fully functional 6 volt AC system and is certainly closer than any others I've seen or heard discussed. IIRC, Bill McDermaid said his rebuilt 6 volt generator is putting out 45 amps but that it's the seperate 12 volt system that's straining to keep up with the demands of the various AC components. You would think that someone would have started producing a 6 volt clutch by now as it seems that it's still lone hurdle yet to get over...

Here is the finished module and how it will look when mounted. Added a relay to disconnect the AC when ign is off. All will be enclosed in the box with just fabric loom exiting and seen.

Also made a plate to mount the compressor on the prewar factory original bracket. I had made a couple of supports to move the bracket & space it more to the side. IMO, Packards method of mounting over the water outlet plain sucks. It is a PIA to have to remove the AC bracket to change a thermostat and even worse when head bolts have to be removed to do it. The supports eliminated that issue as well as the need for longer head studs but added bulk and ugliness.

After all is said and done, the mount is not as pretty as the mount Ross just finished. Am now strongly considering Ross' simple is better method. I had wanted this to look something like Packard would have done so started it and ordered materials to use the factory bracket before Ross showed his handiwork. Belt length has kind of limited the options and position of compressor though. Will have to see how the belt situation is before committing to doing it again. I've found a somewhat limited selection is available on the shorter length large belts needed to work with the the prewar fan pulley drive.

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