Packard Forum Index » Pre-War (1899-1942)

Greetings - I'm experiencing an unknown energy draw on my 1929 Chrysler Model 75. In lieu of an electrical witch hunt, I'm planning to do a battery shutoff switch. To avoid future trouble, I plan to do the same with my 1924 Packard Single 8 143. Unless things were changed during a restoration, both are 6 volt positive ground (would someone change the ground and is there a way to confirm if they did?). Can anyone recommend a specific switch you used and liked? Due to battery locations, I would need to run a cable from the battery for a couple feet or so, if that matters. Thank you!

To check the ground polarity just look at what battery cable runs to the frame…

This is a Packard site.

I am a firm believer that with a 6v battery circuit you absolutely want a top quality heavy duty disconnect switch that can carry the high current of the starting motor when that is operating and will be able carry a larger continuous load other times. Avoid the smaller and generally less expensive 12v switches that are too low in current capacity to do a good job with 6v starters and can even overheat and burn. The intermittent starter load is the important capacity and while the larger continuous current capacity is not as critical on the 20s cars with no accessories to speak of, it is important on postwar cars.. Here is a high current quality switch from Jegs that I can recommended but Summit and other vendors should have something similar. I used it on a 47 with 6v and even used the same switch on my 56 with 12v.




For the additional length of battery cable, with 6v use a minimum of 1/0 cable but 2/0 is better. Too small a battery cable and 6v starting motors definitely do not work well together. Several places will make up specific cables with whatever size wire and terminals you specify. Alternately, if your car has a good spot nearer the battery for mounting the switch you could choose to keep it close to eliminate a lot of the extra cable length and with a bit of ingenuity, work the switch by a knob attached to a pull cable or rotary shaft to bring the control to a more convenient location. I have used both methods on my cars depending on where the switch was easiest to mount. For the rotary shaft extension I could have kept and moved the original pot metal switch lever but elected to go with a black knob a bit more visually pleasing.

This is the switch I bought. It has the same current specs as the one Howard provided…300A continuous and 2000A intermittent.
Battery disconnect switch