6 volt starter turn over slow or fast?

[Bloo]

3 hours ago, maok said:

An interesting experiment would be to place a DC clamp meter (on the amps setting) around the starter motor wire with 12 volts and 6 volts batteries.

 

I could try it later, when I get home.

[Alan Cutler]

2 hours ago, keiser31 said:

This is the way it is on my '31 and it works great....notice the ground on the transmission.

 

What are we looking at....please tell me this is a photo shot taken from the top looking down, and that the oil filled engine/trans/diff is not sitting on its side....

[Spinneyhill]

I think it is on its side, but I expect there are no fluids in it yet. Maybe they didn't yet have cameras that worked looking down.

 

The Mitsubishi Trucks NZ Manager ordered a truck to be sent from the factory dry, for their clever display. The factory queried it several times before they sent a dry truck. They displayed it in Wellington upside down directly above another truck the same, with the punch line being something like "No matter which way you look at it, Mitsubishi trucks ......"

[Bloo]

Car:

1936 Pontiac Master Six, 208cid, 6cyl, 6.2:1

 

Battery 1: Pacific Power Group 1 6 Volt.

Cranking Voltage: 5.545 Volts

Cranking current: 170 Amps

Watts: 942.65

 

Battery 2: Optima Red Top Group 25 12 volt.

Cranking Voltage: 10.731

Cranking Current: 174 Amps

Watts: 1867.02

 

This car already cranks fast on 6 volts. On 12 volts, it sounds ridiculous.

 

 

Edited July 12, 2018 by Bloo (see edit history)

[Sactownog]

the wire gauge I got for Positive and Negative on my 33 6volt is (1 Ga) wire. should I go get some larger wires made or will 1ga be large enough? 

[Bloo]

I think it's fine.

[maok]

9 hours ago, Bloo said:

 

You need the same amount of watts (power) to turn the engine over at a given speed.

 

 

 

Thanks for doing the test Bloo, I don't have a 6 volt battery. I think your results to some degree confirms your statement above. I obviously did not correlate the higher speed to the high power transfer.

I guess we are trying to determine if the starter is being damaged

 

Now the questions are;

     1. Where does that extra power (wattage) go, spinning the starter and hence engine to a higher speed, or heat, or a combination of            both?

     2. And does it do damage to the starter?

 

 

 

 

[Bloo]

7 minutes ago, maok said:

 1. Where does that extra power (wattage) go, spinning the starter and hence engine to a higher speed, or heat, or a combination of            both?

 

I don't know. I think both. A stalled motor draws gobs of current, so I guess since the motor spins faster, it draws less current than the math suggests? The current was about the same, so the wire inside should be happy as long as the waste heat doesn't get out of hand.

 

13 minutes ago, maok said:

 2. And does it do damage to the starter?

 

I guess it could, but people have been getting away with using 6 volt starters on 12v conversions for years, and just being careful not to crank too long. It looks a lot less bad than I expected..

[maok]

Bloo, was your meter set to record maximum current draw? If so, I suspect that maximum would be at the start when the starter is being accelerated then the current would drop to a settled level. I guess when starting an engine the starter would only be operating at maximum current draw any way.

[Bloo]

No, I just let it stabilize and snapped the picture. Maximum current would be just for an instant I think until the starter began turning.

 

I was cranking the engine (with the ignition shut off so it wouldn't start), so I think the numbers are valid. There would be variations as each compression stroke passed, and that could be seen on a scope, but this probe is way too slow for a scope.

Edited July 12, 2018 by Bloo (see edit history)

[Sactownog]

OK, 

 

SO 1 GA WIRE IS OK????

[Silverdome]

4 hours ago, Sactownog said:

OK, 

 

SO 1 GA WIRE IS OK????

 

I would suggest 1/0 or 2/0. See post #9 on page one for the difference in sizes.

[Spinneyhill]

Resistance in wire

 

The resistivity is fixed by the material. Clearly, the larger the wire, the lower the resistance. Remember that A = π.r² so a wire of twice the diameter has a quarter the resistance.

 

Current I = V/R. So for maximum current, you need the smallest reasonable R. With 6 V, there aren't many Volts available to lose through resistance, so use a big wire.

 

1 AWG = 0.2893 mm dia. and 406 Ω/m. https://www.rapidtables.com/calc/wire/wire-gauge-chart.html

 

00 or 2/0 AWG = 0.3648 mmdia. and 255 Ω/m or a 37 % reduction in resistance for a 26% increase in diameter.

 

And with 37 % less resistance, you can draw 58 % more current to operate your starter.

 

So my advice is to use the bigger cable!

Edited July 12, 2018 by Spinneyhill (see edit history)

[Alan Cutler]

1 hour ago, Spinneyhill said:

 

So my advice is to use the bigger cable!

 

Bigger is better in this case....