Ford Truck Enthusiasts Forums - View Single Post - Where is the ammeter shunt located?

#21

11-16-2010, 12:44 PM

JimsRebel

Fleet Mechanic

Join Date: Mar 2008

Location: Washington

Posts: 1,969

Likes: 0

Received 61 Likes on 50 Posts

I have enjoyed reading this thread, made me think and challenged my electrical theory.

I guess I would have to say current is “more” correct then voltage as far as what cause the needle to deflect. But in my mind it is easier for me to understand the concept as… applied voltage dropping across the internal resistance of the meter is what causes the current to flow internally in the meter movement. All of the resistances in the circuit are fixed and thus in my mind, the changing voltage across the shunt ends up causing the amp meter needle to move…while this analogy might be technically flawed… my mind just likes it better.

I guess I think you are both correct….

Anyway moving on to the G3 ALT “upgrade”… I still have not installed the 3G ALT I recently got at the junk yard as I am frustrated with loosing the amp meter. I really don’t need the extra amps, I just don’t like my current fire hazard 2G ALT, and it’s also the worst designed ALT I have ever seen.
So I have thought about making my own shunt but I don’t know the currently installed amp meter “Rm and Ifs”…. Here a good link to what I am talking about….

http://www2.ece.ohio-state.edu/~fior...onvalMeter.pdf

I do plan on doing some bench testing with a ford amp meter at some point down the road.
Another idea would be to just de-rate the 3G with a 60 circuit breaker and using the current wiring harness/shunt. The only risk I can see with this plan is popping the CB with a totally dead battery and thus forcing me to idle the engine, to limit ALT amp output, until the battery is charged enough to draw less than say... 20amps.

Any thoughts…

Here is a photo of my ALT harness showing the “shunt” (black looking wire) between the large black splices. The small wires off the splice points feed the amp meter.
.

Reply Like