Ammeter question

Discuss all things Model T related.
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules

Topic author
TheSaintDiscJockey
Posts: 216
Joined: Sun Jan 06, 2019 5:23 pm
First Name: Brooks
Last Name: Schlieben
* REQUIRED* Type and Year of Model Ts owned: 1923 TT
Location: Levittown, Pa.
MTFCA Number: 32304
Board Member Since: 2015

Ammeter question

Post by TheSaintDiscJockey » Wed Oct 21, 2020 2:06 pm

When my 1920 T is running on battery or magneto, how should the ammeter read?
If not at all, where should I trouble shoot?
Thanking all in advance.

User avatar

Humblej
Posts: 1690
Joined: Sun Jan 06, 2019 12:23 pm
First Name: Jeff
Last Name: Humble
* REQUIRED* Type and Year of Model Ts owned: 1926 Canadian built coupe, 1924 TT C-cab, survivor 1924 roadster
Location: Charlevoix, Mi
MTFCA Number: 28034
Board Member Since: 2006

Re: Ammeter question

Post by Humblej » Wed Oct 21, 2020 2:22 pm

Ammeter is on the battery circuit and is separate from magneto. If generator is putting out ammeter should show a pos. If you have no generator output and car is running on bat, and, or the lights are on and or the horn is blowing, the ammeter should show a neg. If the generator is putting out and you see a pos on the ammeter, then turn on the lights, the ammeter may go to zero or into neg. How far pos ammeter goes with lights off depends on how the third brush is set. If you drive the car for long distinces, you should set the third brush to give a low charge. If you drive short dist, set for higher charge.


Stu Tomlinson
Posts: 44
Joined: Tue Mar 19, 2019 3:35 pm
First Name: Stuart
Last Name: Tomlinson
* REQUIRED* Type and Year of Model Ts owned: 1911 Touring, 1913 Huckster, 1924 Touring, 1927 Tudor
Location: Paola, KS
MTFCA Number: 27355

Re: Ammeter question

Post by Stu Tomlinson » Wed Oct 21, 2020 6:20 pm

The meter should read up to 10 amps with the lights off and at a fairly good engine speed. If there is no charge the very first place I would troubleshoot is the generator cut-out. Simply jump around it with a jumper on each of the cutout posts. If it registers a charge then you have found the issue. After that I would use a volt meter to see if the generator is putting out any charge.
Stu

User avatar

gcomo
Posts: 48
Joined: Mon Jan 07, 2019 8:55 am
First Name: Gary
Last Name: Como
Location: Central Ma
MTFCA Number: 49625

Re: Ammeter question

Post by gcomo » Mon Oct 26, 2020 9:36 am

What is the procedure for testing the output of the generator?


Altair
Posts: 365
Joined: Thu Jan 17, 2019 11:52 am
First Name: David
Last Name: Menzies
* REQUIRED* Type and Year of Model Ts owned: 1926 Touring and 1915 Touring both Canadian models
Location: British Columbia
MTFCA Number: 27825
Board Member Since: 2012

Re: Ammeter question

Post by Altair » Mon Oct 26, 2020 10:38 am

I would firstly assure that the commutator is clean, just a slight film of oil will prevent it from charging. The generator should be sealed from the crankcase but a slight vapor leak can contaminate the commutator.


jab35
Posts: 892
Joined: Sun Jan 06, 2019 12:28 pm
First Name: James
Last Name: Bartsch
* REQUIRED* Type and Year of Model Ts owned: '26 Coupe
Location: Dryden, NY 13053
MTFCA Number: 30615
MTFCA Life Member: YES

Re: Ammeter question

Post by jab35 » Mon Oct 26, 2020 10:39 am



TrashMan
Posts: 39
Joined: Mon Sep 28, 2020 6:37 pm
First Name: Chuck
Last Name: Griffin
* REQUIRED* Type and Year of Model Ts owned: 1925 Tudor Sedan
Location: Hanna, IN
MTFCA Number: 31570
Board Member Since: 2020

Re: Ammeter question

Post by TrashMan » Mon Oct 26, 2020 11:02 am

So if the ammeter is on the battery circuit, if you run your car on mag, is the battery being charged? I start my car on battery then switch it to mag right away. Does the mag charge the battery?


Norman Kling
Posts: 4068
Joined: Tue Jan 08, 2019 1:39 pm
First Name: Norman
Last Name: Kling
Location: Alpine California

Re: Ammeter question

Post by Norman Kling » Mon Oct 26, 2020 11:44 am

One other thing I will mention. If you are using an alternator, you would show some charge at idle, but on a T generator, it will not show a charge until your engine is either on a fast idle or driving along.
Norm

User avatar

jsaylor
Posts: 334
Joined: Sun Jan 06, 2019 5:25 pm
First Name: John
Last Name: Saylor
* REQUIRED* Type and Year of Model Ts owned: 1921 Touring, 1927 Tudor
Location: Citrus Heights, Ca
MTFCA Number: 1695
MTFCI Number: 23870
Board Member Since: 1999

Re: Ammeter question

Post by jsaylor » Mon Oct 26, 2020 11:56 am

"So if the ammeter is on the battery circuit, if you run your car on mag, is the battery being charged? I start my car on battery then switch it to mag right away. Does the mag charge the battery?"

The only thing that changes when you switch to mag is the feed to the coils. Everything else stays with the battery. The generator continues to charge the battery.

User avatar

TRDxB2
Posts: 5407
Joined: Tue Jan 08, 2019 4:56 pm
First Name: Frank
Last Name: Brandi
* REQUIRED* Type and Year of Model Ts owned: Speedster (1919 w 1926)
Location: Moline IL
Board Member Since: 2018

Re: Ammeter question

Post by TRDxB2 » Mon Oct 26, 2020 12:18 pm

The magneto does not charge the battery but it can be set-up to do so. Remember the magneto puts out AC voltage. But since you have a generator it would be more complicated to do so and then whats the point.
http://www.mtfca.com/discus/messages/70 ... 1498438118
useful discussions on how to charge a battery from your magneto
http://www.mtfca.com/discus/messages/41 ... 1416288062
If you look at the wiring diagram yellow connection points show the path from the generator to the ignition switch and battery. The red connection points are fro the magneto. The ignition switch is actually two switches: the key i used to select the voltage source and the lever to select the lights
Attachments
wire.jpg
The past is a great place and I don't want to erase it or to regret it, but I don't want to be its prisoner either.
Mick Jagger

Post Reply Previous topicNext topic