10 amp discharge

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Model T Ford Forum: Forum 2018: 10 amp discharge
Top of pagePrevious messageNext messageBottom of page Link to this message  By Jon Crane on Saturday, December 29, 2018 - 05:42 pm:

My 25 T. Had it running today and all was good. Suddenly when running on Batt, the amp gage went from 6 amps charge to a 10 amp neg discharge. Turn the motor off and gage shows continued 10 A discharge. no lights on, no apparent shorts.
Disconnected battery for the night and will address tomorrow. Any suggestions?


Top of pagePrevious messageNext messageBottom of page Link to this message  By arnie johansen on Saturday, December 29, 2018 - 09:03 pm:

Is your cutout on top of the generator working correctly?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jon Crane on Saturday, December 29, 2018 - 10:04 pm:

Arnie
Do not know. That will be the first thing I check in the morning. Any suggestion for an easy and quick check?
Thank you


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Saturday, December 29, 2018 - 10:29 pm:

Ford Service chapter 39 will help, states if discharge at ammeter, with engine not running, the short is beyond the ammeter, so start checking all wiring. Could be the cutout to ammeter or other.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Brandi on Sunday, December 30, 2018 - 01:02 am:

The purpose of the cut-out is to break the connection of the generator from the electrical system when the battery power is greater than that being produced by the generator. Original cut-outs used mechanical points - sometimes they would stick and cause havoc and in turn drain the battery. I have read in the forum that if you loosen the fan belt and reconnect your battery and the generator starts running like a motor its the cut-out not doing its job. If you haven't solved the problem others may want to know if your 6 or 12 volts . generator or alternator and what type cut-out it is


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Stroud on Sunday, December 30, 2018 - 01:29 am:

Frank, the fan belt has nothing to do with the generator, it is gear driven. :-) Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Sunday, December 30, 2018 - 01:42 am:

If it's showing a discharge with the motor off, just disconnect the wire to the generator (with the motor OFF!) and see it it stops showing a discharge. If so, then there's your problem, and it's likely you have a generator problem if it was charging and then started discharging.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Sunday, December 30, 2018 - 02:12 am:

That wire is hot at all times, do not let it touch anything. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Peter Claverie, Memphis TN on Sunday, December 30, 2018 - 07:39 am:

And don't run the engine with that wire disconnected, unless you ground the terminal you removed it from.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Sunday, December 30, 2018 - 08:18 am:

When you touch the wire back to the cutout and get a spark, that is also an indication the cutout is defective.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Sunday, December 30, 2018 - 08:21 am:

Then too, if you accidentally hit the light switch, you would need about 16 amps and with the generator providing 6 amps, the battery would provide the other 10 amps and show a correct - 10 amps on the meter.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Brandi on Sunday, December 30, 2018 - 10:55 am:

Fan Belt? -oops was late at night not thinking - agree wrong car. What do you guys think about this Disconnect the battery and cut-out from the generator and leave the wire to it connected. With the switch off - reconnect the battery and test for voltage from the terminal on the cut-out that was connected to the generator to ground. If you get a voltage reading - its the cut-out If an old cut-out tapping on it may release the stuck points - if it has a diode it needs to be replaced. If your going to replace the cut-out consider the one that includes a Voltage Regulator


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Sunday, December 30, 2018 - 05:43 pm:

The circuit is grounded somewhere beyond the ammeter. So the wiring between the battery, starter switch and terminal block should be OK. I would suspect somewhere between the terminal block and the generator including the switches for lights and ignition switch. If the light switch is off it should not include the light circuits. One place which is not often suspected but could cause the problem would be the screws in the terminal block being too long and when tightened they touch the steel firewall. If the problem were in the generator itself, the problem would go away when the engine is turned off because of the cutoff. However if the cutoff itself were defective causing the circuit to ground, it is a possible cause. So do as suggested above and remove the hot wire from the cutoff and insulate the connection at the end of the wire. If the ammeter still shows discharge, the problem is not in the generator or cutout. Anyway, I suspect the problem to be behind the instrument panel or in the wiring between the panel and the terminal block or switch.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Royster on Sunday, December 30, 2018 - 07:50 pm:

Watch your amp gauge and tap the cutout with a screwdriver handle. If the amp gauge goes back to normal your cutout is sticking. Been there, done that!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jon Crane on Monday, December 31, 2018 - 03:20 pm:

Found the short. Generator checked out OK.
Short is on the mag post, Took wire off the mag post and taped it up and no more short. Will next take the mag post out and see what is happening. Any suggestions as I do not know if the car ran on mag or not.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Monday, December 31, 2018 - 03:29 pm:

Well, if it did or it didn't, it will likely not run on Mag now.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brad Marble - New Hamshire on Monday, December 31, 2018 - 03:45 pm:

Jon; You don't have a short circuit or a ground in your wiring,if you did you would see full discharge and smoke, you have a problem with your generator, not real sure what it is but it is not the cutout.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jeff Humble Northern Michigan on Monday, December 31, 2018 - 04:24 pm:

Jon, the mag circuit and the battery/charging/lighting circuits are independent of each other. The only possible mixing of mag and charging circuits would be through a malfunctioning ignition switch. The ammeter will only show current flowing to or from the generator, the lights, the coil box, or a short to ground. The mag circuit only goes from the mag post on the hogshead to the ignition switch and then to the coil box, period. The mag cannot power the lights or gen without some kind of a problem with your ignition switch allowing mag and battery circuits to co-mingle. Time for an ignition switch restoration or replacement.

And hello from Flivver Farms in Charlevoix.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Monday, December 31, 2018 - 05:35 pm:

Jon

As Jeff noted, if you found a 'short' at the mag post, then that red wire from the mag post to the terminal block on the firewall, continues to the ignition switch.

A bad switch can put 6vDC current that is on the BAT side of the switch key tumbler to the MAG side. That will send DC amps to the magneto coils and will discharge the magnets on the flywheel.

Doubtful now your mag works if there was current shorting from the red wire to the mag post.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jon Crane on Monday, December 31, 2018 - 05:48 pm:

My T has a wire gong from the Mag side of the ignition switch to the amp meter. Heavy green. Maybe if I take that off?

I checked circuit from the mag post to ground and have continuity with no wires on the mag post.

Car is a barn find and had not been run in a long time. Many of the wires to the lights were cut and deceased owner's wife told me he always had electric problems. I have rewired with new harnesses.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jeff Humble Northern Michigan on Monday, December 31, 2018 - 06:10 pm:

Jon, pm sent.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Tuesday, January 01, 2019 - 10:56 am:

Is that mag side of the switch still connected to the magneto? If so, your magneto is discharged and the short to ground is through the magneto. The wire to the ammeter should only be connected to the batt side of the switch. However, some people have connected battery to both sides of the switch but disconnected the wire to the magneto. In that case the engine would run on battery in either switch position. Sometimes a person who has a T for sale will do that so that they can start the engine on battery and show the potential buyer "See it runs on magneto" Which of course is a lie.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, January 01, 2019 - 01:18 pm:

At this point, if the problem has been there for a while, the only thing to do is check mag out put, service the switch and check how it is wired. If the magneto is dead, google "MTFCA; magneto recharge". In the mean time, run the car on battery and have fun. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jon Crane on Tuesday, January 01, 2019 - 04:55 pm:

Straightened out the wiring and have the red mag wire going to the mag side of the switch and Batt wire going to the battery. Have setup the amp gage correctly and car starts and runs on Battery.
Have not hooked the red mag wire to the mag post as am still concerned about the dead short from the center of the mag post to ground. Will address that next weekend as I could not get the oiler tube undone from the mag post.


Amp gage is not showing a 10 amp short anymore. When the engine is running, the gage is still at zero charge, but showing a slight discharge when ignition is on and car is not running. Shorted across the cutout as suggested in the T manual and amp gage was pegged, so I guess the generator is going and maybe the cutout is giving me problems.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Tuesday, January 01, 2019 - 05:43 pm:

John, you are measuring from the Mag post through 16 strips of solid copper wire of about 6 feet each when unwound to the ground.

I unwound a few and measured them several years ago, but I forget exactly how long they are now.

Most measurements from the Mag post to ground are about 1 to 1.5 ohms.

How accurate is your meter?


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A Bartsch on Tuesday, January 01, 2019 - 09:10 pm:

Six volts across a 1.5 Ohm resistance gets pretty close to the current he's reporting.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Tuesday, January 01, 2019 - 09:32 pm:

7 volts at the generator and 1 Ohm - 7A
7 volts at the generator and 1.5 Ohm - 4.7A


Top of pagePrevious messageNext messageBottom of page Link to this message  By arnie johansen on Tuesday, January 01, 2019 - 09:33 pm:

Jon:

When you shorted across the cutout and the amp gage was pegged, do you mean to the plus side or to the minus side?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jon Crane on Wednesday, January 02, 2019 - 02:07 am:

Short across cutout went positive...pinned the am meter positive to right.
I am going to order a cutout/regulator tomorrow.


Top of pagePrevious messageNext messageBottom of page Link to this message  By arnie johansen on Wednesday, January 02, 2019 - 11:08 am:

If your ammeter is connected properly then if the ammeter went positive when the cutout was bypassed, it would indicate that the generator has an output.

To check proper hook up of the ammeter without the engine running and headlights on, the ammeter should show discharge.

If you generator is still good, be careful not to run it open circuit, as that can ruin the generator. If you run the car with the generator connected you should short its output to ground to prevent generator failure.

Best to wait until you get another cutout and connect it properly before driving the vehicle.


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