6 Voltage

[rusty6]

This is a car post, not tractor. Although I'm sure some of you are still running six volt systems on your tractors. I acquired this old voltage tester and was trying it out on the 52 Merc yesterday. The Merc has always been slow cranking with the six volt battery even with the heavy cables and a tractor battery. I'm wondering if the starter is weak and in need of some work. The voltage tester appeared to drop to 5 volts while cranking. I don't know if this is normal or below. I got some of it on video because I could not push the starter button and watch the meter at the same time.

 

[JMOR]

5V during cranking is not that unusual, in my experience. Usually 200+ amperes. That little tester puts very little load on the battery, most of those wouldn't even produce a 20 ampere draw.

 

[Janicholson]

I also think 5 is OK ish, however 5.5 is more like the 11 expected as drop on a 12v system. It is chilly so that may be considered normal. What oil is in it? Jim

 

[M-MAN]

I think a 1 volt drop on a 6v system is on the higher end of the spectrum. Most drop more unless it is bright, shiny and in perfect condition. Seldom happens in the real world.

 

[buickanddeere]

Should be 5.5V across the starter and distributer .
How much across the battery posts while cranking ?

 

[rusty6]

Should be 5.5V across the starter and distributer .
How much across the battery posts while cranking ?

The test cables were connected to the battery posts. The meter does not show up too well in the video as I could not find a good place to prop up the phone to record. Still looked like 5 volts to me. 15w-40 oil in the engine but it was 17 degrees outside.

 

[buickanddeere]

More demand by the starter than the battery could provide .

 

[John T]

Its pretty common for some old 6 volt systems NOT to be fast crankers even with perfect equipment.......While 5 volts at the starter when cranking can function (subject to many variables) sure 5.5 is preferred. You need a heavy rated high CCA battery,,,,,,,,,big cables and perfect connections and grounds,,,,,,,,,,a perfect switch/solenoid,,,,,,engine thats not a hard cranker etc. Just too many unknowns here to say more

John T

 

[JD Dave]

This is a car post, not tractor. Although I'm sure some of you are still running six volt systems on your tractors. I acquired this old voltage tester and was trying it out on the 52 Merc yesterday. The Merc has always been slow cranking with the six volt battery even with the heavy cables and a tractor battery. I'm wondering if the starter is weak and in need of some work. The voltage tester appeared to drop to 5 volts while cranking. I don't know if this is normal or below. I got some of it on video because I could not push the starter button and watch the meter at the same time.

Hey Rusty, I always like your posts. I've been around a lot of 6 volt machines since the old days. I had my share of pre-1954 cars with 6 volts. Six volt systems were a constant problem, - dealing with only 6 volts, we are always challenged with maintaining about 5 1/2+ volts to the starter. If everything is right, it'll work. Load check the battery, clean and confirm all connections and reburbish/clean/rebuild the starter. If there's any resistance in the wiring and starter, - you lose voltage. Most times this will cure the problem.

 

[old-9]

This is a car post, not tractor. Although I'm sure some of you are still running six volt systems on your tractors. I acquired this old voltage tester and was trying it out on the 52 Merc yesterday. The Merc has always been slow cranking with the six volt battery even with the heavy cables and a tractor battery. I'm wondering if the starter is weak and in need of some work. The voltage tester appeared to drop to 5 volts while cranking. I don't know if this is normal or below. I got some of it on video because I could not push the starter button and watch the meter at the same time.

 

[old-9]

Was this on a cold start? And if so was the drop same or lower when the engine was warm? Nice car by the way. joe

 

[rusty6]

Was this on a cold start? And if so was the drop same or lower when the engine was warm? Nice car by the way. joe

Thanks Joe. Yes cold but indoors. Never tried a warm test. I have a 39 Deluxe with a slightly smaller flathead V8 and it seems to turn over twice as fast as the Merc on six volts. I wonder if the automatic transmission in the Merc creates the extra drag on the starter?

 

[Hobo,NC]

5V during cranking is not that unusual, in my experience. Usually 200+ amperes. That little tester puts very little load on the battery, most of those wouldn't even produce a 20 ampere draw.

He would be better served to observe the voltage while cranking the engine. That would be a true load test under normal conditions. I don't trust those analogy gauges I always back the up with a DVOM.

 

[Janicholson]

The auto trans (Merc-O-Matic?) doesn't take much energy to spin. The Merc engine is likely higher compression and more friction than the other engine. My 51 GMC has a 8 year old 6 volt battery and spins slow, but never fails to start on the third stroke of a piston. 270 inch 6cyl. I found a 1.1 ohm coil that helps. The ground cable is doubled to the block and chassis. The Positive to the starter is OOga. and good, and 14 inches away from the battery. It also has an electric fuel pump that I let run for 30 seconds when starting after a winter storage, Manual choke also helps. I live with the slow spin as long as it starts. Jim

 

[rusty6]

The auto trans (Merc-O-Matic?) doesn't take much energy to spin. The Merc engine is likely higher compression and more friction than the other engine. My 51 GMC has a 8 year old 6 volt battery and spins slow, but never fails to start on the third stroke of a piston. 270 inch 6cyl. I found a 1.1 ohm coil that helps. The ground cable is doubled to the block and chassis. The Positive to the starter is OOga. and good, and 14 inches away from the battery. It also has an electric fuel pump that I let run for 30 seconds when starting after a winter storage, Manual choke also helps. I live with the slow spin as long as it starts. Jim

Its been explained to me over on the ford barn that the automatic equipped cars had a different starter drive with a smaller gear on the bendix drive. In effect gearing it down. Slower cranking speed results. Apparently it is normal for the automatic equipped cars to turn slower on the starter.

 

[gene bender]

This is a car post, not tractor. Although I'm sure some of you are still running six volt systems on your tractors. I acquired this old voltage tester and was trying it out on the 52 Merc yesterday. The Merc has always been slow cranking with the six volt battery even with the heavy cables and a tractor battery. I'm wondering if the starter is weak and in need of some work. The voltage tester appeared to drop to 5 volts while cranking. I don't know if this is normal or below. I got some of it on video because I could not push the starter button and watch the meter at the same time.

 

[gene bender]

This is a car post, not tractor. Although I'm sure some of you are still running six volt systems on your tractors. I acquired this old voltage tester and was trying it out on the 52 Merc yesterday. The Merc has always been slow cranking with the six volt battery even with the heavy cables and a tractor battery. I'm wondering if the starter is weak and in need of some work. The voltage tester appeared to drop to 5 volts while cranking. I don't know if this is normal or below. I got some of it on video because I could not push the starter button and watch the meter at the same time.

why not get the starter refreshed its only 70 pluss yrs old

 

[560Dennis]

Biggest trouble I’ve had with 6 volt (tractor) is poor grounds to chassis,corrosion on the cables. Oh too small a battery

 

[rusty6]

why not get the starter refreshed its only 70 pluss yrs old

Thats what I am considering but I was hoping I could rebuild the spare one and have it ready to bolt in when I take out the original. Not going to work though.

 

[rusty6]

Biggest trouble I’ve had with 6 volt (tractor) is poor grounds to chassis,corrosion on the cables. Oh too small a battery

Got the new (heavy) ground cable and an oversize tractor battery in the car but it is slow cranking. Apparently that is just a characteristic of an automatic transmission equipped car on six volts.