6V/12V question

[purplepickup]

I'm ebaying a bunch of stuff off a 30 Chevy (doodlebug, for those that remember) and I want to see if some of the electrical things work but I don't have a 6V battery.  I'm pretty dumb about these things.  The parts that I want to check are amp gauge, starter, & horn.  Will it hurt to put 12V to any of those for a quick check?  

If I figure out how to spin the generator fast enough, how should I check it to see if it's generating?  There's one wire coming out of the side, under the regulator that bolts to the generator body.  

The temp gauge is mechanical and when I heat the area around where the sender mounts to the block the needle goes up.  Can I assume that if it works at all, it's still accurate?  I guess I can boil water and stick it in and check it.  The faces of the gauges are in really good shape and if they work they bring quite a bit on ebay.  Any ideas on how to check the oil pressure gauge?  Can I put low air pressure to it?.

I know, these are stupid questions but I don't want to screw something up by using my usual method of trial and error.

It's kind of ironical that I couldn't even get $200 out of the whole car but so far just the carb and air cleaner are bringing more than that and they still have a couple days to go.

[Jokester]

Hi George,

The horn and the starter can handle 12V briefly.  I've run 6V starters for years on 12 volts.  Just shortens the brush life.  Not sure about the amp gauge.  Also not sure about the accuracy of the temp gauge, but it at least appears to function.  You won't be able to go over 212° unless you have some means to put it under pressure.  Low air pressure should be OK on the oil gauge.  Crank your regulator down to about 30 psi and go for it.

Hope this helps.


.bjb          

[58 Yeoman]

6 volt horns sound good with 12volts applied.  I used to run them on 12v cars, when they were more plentiful.

[34ford]

George,

Might take the amp guage with a couple of short pigtails on it down to the local Tractor Supply, Wheelers or what ever farm store you have in the area and go to the battery section and check it out on a 6V battery. Around here they are setting on racks out in the main store.

bob

[Crosley.In.AZ]

I have run 12 volts to my Crosleys.  Starter spins the little engine purty dang fast!

The AMP gauge jumps every where reall fast.  Problaby not good for the volt regulator, I dont do the 12 volt theng too often or long.

the 6 volt batterys do not seem to last very long , so I stopped buying them

[zzebby]

The starter and horn will be ok on 12 volts,  but don't put the ammeter across a 6 volt battery............NNNNNOOOOOHHHHH..........it'll melt  those pigtails in a microsecond and the store people will have to get the first aid kit for your burnt fingers after you stop screaming.
Old cars usually had actual amp gauges where the heavy lead (10 gauge or thicker) went thru it or just thru a loop on the back and read the current via the inductance (one turn for you EE's out there.)  The 6 volt battery would see this "test"  as a direct short circuit and send about a 100 amps thru those wires.  Probably would not hurt the gauge, would peg it momentarily,  but you would not notice, your entire focus would be the flesh burning.........yours.
Modern "amp gauges' are really voltmeters, just calibrated to read as ammeters.   I'm  99.9% sure that is not what is on a 31 Chevy.   You can easily tell,  if the stock wires are big then it's an  ammeter.   If the wires are tiny then it's a voltmeter.
Amps are amps.  They are indifferent to voltage,  don't care if its 6 volts or 60 volts.   If you want to see if it works (and if it really is an ammeter)  then you need some kind of "load"  to make current flow and do something.  Look around your shop for an old fan motor, blower or wiper motor.  These things will pull some amps so you can see the needle move.  A light bulb will not pull enough current to see the needle move.  First use some short wire pigtails to check that the fan motor or whatever works when touching a handy 12 volt battery.  Then run one of the wires thru the ammeter (you may need another wire depending upon whether the ammeter has a loop on the back or two big terminals)  and then touch it to the battery again.  Ammeter will move now.
Most of those old ammeters are pretty much indestructible and it probably still works fine.

[PeterR]

Temp gauge.
Immerse in boiling water see if it reads around the 212 degree mark.

Oil pressure.
Pressure is pressure regardless of whether it is oil or air.     Just turn the regulator down to a few psi then slowly increase until you max out the gauge.   Check the oil gauge displays a reading close to the air pressure gauge,

Amp gauge.
DO NOT PUT PIGTAILS ACROSS A 6V BATTERY. This would be a once-only test to confirm the gauge is no good.     The instrument has almost zero resistance so putting it across a battery would be applying a dead short and the massive current will burn out the meter in an instant.

An amp gauge does not care about voltage, only the current going through it.  You can test with a 12V battery and headlight globe.   One lead from a battery post to meter terminal.  Next lead from other meter terminal to lamp terminal.  Last lead from other lamp terminal to second battery terminal.  If you are using a 60-watt lamp expect the gauge to read about 5A.  Reverse the meter connections, and now it should show same current but on the other side of the zero mark.   If the bulb does not light or the meter does not move it is a fisser.

Starter motor and horn
As others have said running on 12 volts will be OK for short periods.     Plenty of VWs have been operating them in daily service for years.

Only problem testing the starter without load is that it is not a thorough test.   An electric motor with bad armature windings and chunks of commutator missing will still run no load, so you will need to work out some way of applying a dummy mechanical load.    An autolec has a bench tester that provides this.

Generator
This is the most difficult to test because you need to drive it while providing a real load and monitoring output volts and current.   You can do it at home but there is too much fiddling around.   Either sell as unknown condition or take to an autolec to test.

[Russ]

George:

1.  Horn can take 12 V
2.  Starter, take it to Auto Zone, they test this stuff for free.
3.  Amp guage, see # 2
4.  Generator, see # 2
5.  Temp guage.  Boil a pan of water, using a manual temp guage like for testing refrigerator for temp.  Put both in the water, not the guage, just the sender unit,  and they should read about the same temperature.
6.  Oil pressure guage, test with low volume of air off the compressor.  If yours is like mine, I have a ball valve and can cut it way way down. Then hit it with the air nossle.
7.  What da heck else did you ask about.  

My forgetter done forgot.

[kb426]

You don't have a 6 volt battery charger?

[purplepickup]

Duh, (he says as he fluffs his blond hair) ....yes I've got two 6V chargers. :oops:

Thanks for the good info guys.  At least now I have some guidelines if I decide to try to see if this stuff works.  I don't plan to guarantee that anything works but I might mention that I hooked it up and describe what happened....like if the starter spins under power without a load, but I'm not going to take it anywhere and have it tested.  The auctions are still AS IS condition.

George

[Crosley.In.AZ]

Duh, (he says as he fluffs his blond hair) ...George

heck I just wish I had more hair.

never thought about the amp gauge hook up / smoke test....not designed for that terminal to terminal deal

[Sean]

Duh, (he says as he fluffs his blond hair) ....yes I've got two 6V chargers. :oops:

Last time I looked, it definitely wasn't Blonde...

[Dave]

Duh, (he says as he fluffs his blond hair) ....yes I've got two 6V chargers. :oops:

Last time I looked, it definitely wasn't Blonde...

                           
Dave

[48 Suburban]

My favorite old guy mechanic, he's 80, checked the generator that I bought from him with the wire brush on a bench grinder and a screw driver. He spun the pulley with the grinder, and used the screw driver to arc from the out put terminal to the case. He is really a safety oriented guy. If you can find an old service manual from a sixties chevy, they have a diagram on how to hook up the wire to turn the gen into an electric  motor, if it spins it is fine. This is the same principal that a cub cadet starter/gen combo uses.  Jay