Starting Problem

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ROBERTHOOPS
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Starting Problem

Post by ROBERTHOOPS » Sun Jul 14, 2019 4:19 pm

My 6-volt, group 1 battery won’t crank my ’27 touring. After an overnight charge, the battery measures 6.25 volts and it passes a load test. When I jump start it with a 12-volt battery, it starts right up. When running, the ammeter registers like it always has. I’m a bit suspicious of the foot operated starter switch but, where else should I be looking?
Thanks in advance.
Robert

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Steve Jelf
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Re: Starting Problem

Post by Steve Jelf » Sun Jul 14, 2019 4:27 pm

Check grounds and other connections for clean metal-to-metal contacts and tightness. The switch could be your problem, but a weak connection is more likely. Do you have big enough cables?
The inevitable often happens.
1915 Runabout
1923 Touring

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ROBERTHOOPS
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Re: Starting Problem

Post by ROBERTHOOPS » Sun Jul 14, 2019 6:28 pm

Thanks Steve.
I pulled off the battery to switch cable and saw that some of the insulation is worn off and that it has been shorting against the frame. I bought the car in 1989 so it has probably been doing this for a long time. I reinstalled it and hooked up my heavy-duty jumper cables to it and a hot 12-volt battery. It cranks that way like it should with a 6-volt battery. I never noticed a cranking problem before as it always started instantly or free started.
I plan to buy a new HD cable and cable support from Lang’s. I’m hoping that’s all it needs.

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JohnH
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Re: Starting Problem

Post by JohnH » Mon Jul 15, 2019 12:06 am

Measuring the voltage at each of the following points while the starter motor is cranking will narrow it down: Positive battery terminal, battery side of starter switch, motor side of starter switch, starter motor terminal. A less accurate test, if no meter is available, is to feel the all these connections after cranking - the warmer they are the higher the voltage drop. The braid from the negative battery terminal to chassis is another place voltage drop can be a problem; particularly the chassis connection. If the starter won't crank with at least 4.5V at its terminal, there could be a fault in the starter motor itself. Switching on the dash lamp and observing its brightness while cranking also gives an indication of the wiring and battery condition.
Clutch drag is also something to be wary of; if the engine is hard to turn by hand, it will also be difficult for the starter motor.


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Re: Starting Problem

Post by Craig Leach » Mon Jul 15, 2019 12:50 am

Hi Robert,
Steve & John are correct. May I put in my two cents? If you have a infrared thermometer use it so you don't end up with a nut tattoo on one or more fingers. And Google how to ( voltage drop ) test a starter circuit you will find it a more accurate method. Good luck

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Charlie B in N.J.
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Re: Starting Problem

Post by Charlie B in N.J. » Mon Jul 15, 2019 6:38 am

braided negative cable ? lose it.
Forget everything you thought you knew.


Poppie
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Re: Starting Problem

Post by Poppie » Mon Jul 15, 2019 7:07 am

C.B in N.J.
"lose it" What do you mean? There is a lot of Cirmil's in braided cable and it is very flexable. N.

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Charlie B in N.J.
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Re: Starting Problem

Post by Charlie B in N.J. » Mon Jul 15, 2019 7:17 am

I mean they go bad. Lots of resistance. They heat up because of it and even with good clean connections you'll still have a slow cranker. Experience talkin' here.
Forget everything you thought you knew.


Piewagon
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Re: Starting Problem

Post by Piewagon » Mon Jul 15, 2019 11:30 am

This thread is rather confusing from start to finish. Here is what I mean.

A battery that was charged overnight and then measured with the battery charger just disconnected would measure higher than 6.25 - it would measure more like 6.8 or higher. It would then slowly (much later) drift back to 6.35 or so.

If the hot lead of the battery was touching the frame that would have ruined a good battery because a good battery would have likely welded itself there and melted by literally boiling and that is something you don't want to witness since the battery will be literally destroyed in a cloud of stink. You don't want to go anywhere near a battery that is melting since it is already ruined and you can only get hurt by it.

Check your digital voltmeter on your modern car battery after driving that car for awhile and notice that it will be in the 13V+ range for awhile after driving it since it will have been charging most of that time. Batteries are slow to change their voltage back to the quiescent voltage once charging has stopped. 6.25 is close to normal for a battery that is charged up and OFF the charger for a day.

The correct size cables for a 6V Model T system are designated as 1/0 which is way heavier than typical 12V modern cables which don't work on the T usually until the starter is rewound to become a 12V starter. That is really not a necessary modification for a T IMHO.

All connections starting at the frame and ending at the starter stud MUST be clean BRITE and TIGHT. A T is easy to turn over with a 6V starter that is on a car with good cables and a good foot switch.

Battery disconnect switch if installed is usually (or always) a problem which is why most of us don't use them.

The most accurate way to find out what part(s) are problematic is to crank the starter over with the ignition turned off. Do it long enough for the parts to warm up and then stop and run your hand over every connection starting at the frame ground bolt. Touch each cable connection and cable all the way to the starter stud. The hot points are the high resistance points and thus are the trouble places.

Good hunting.

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