amp meter

[tahoe healey]

In Norm Nocks book, Tech Talk, the instruction about installing an amp meter indicates connection to terminal "A" on the regulator. I got all kings of alphabet but no "A". What gives? I haven't found anything specific in the archives.

 

[GregW]

Hi Rich,
If you look at the earlier diagrams, the "A" terminal has brown wires attached to them. It would make sense that you'd follow the brown wire on the later regulator to the "b" terminal. :laugh:

 

[tahoe healey]

Thanks, Greg. There were many brown wires and I wasn't sure which would work.
Any thoughts on an in line fuse?

 

[GregW]

Honesty, I'm not a big fan of ammeters. <span style="text-decoration: line-through">If I was to install one though, I'd remove the brown wire from the ignition switch and put it on the ammeter. Then I'd get another brown wire of the same gauge and go from the other terminal of the ammeter back to the ignition switch.</span> The reason for this is to minimize the amount of new wire and to utilize the protection of the wiring harness as it passes through the firewall. Since the ammeter reads the full amperage of the system, you'd need a big fuse or your car will stop when you hit the horn on a cold rainy night. :wink:

After further reflection, I realize this wouldn't work. The Ammeter must be wired between the regulator and the starter solenoid. So two wires would need to be added through the firewall.

 

[Bob_Spidell]

Greg,

Just curious, why do you not like ammeters?

 

[GregW]

Hi Bob,
I don't like adding something that if it fails, everything fails. A voltmeter, if you wanted to add one, is relatively low amperage and can be fused. If it fails, you might not notice until you looked at it.

 

[TimK]

I am glad that the P.O. installed an ammeter. It saved my OD solenoid when I noticed a very high amperage going through the gauge when the OD was on. Mine was wired with two 10 gauge wires (very heavy duty) from the D terminal and back. It only measures charging (or else it is hooked up backwards and only measuring draw, I'm not sure which, anyway it only shows activity to the plus side.) It is mounted below the steering wheel and I have to look around the wheel/spokes to see it.

 

[Keoke]

Yes that Greg fella is correct. Further, I really do not know what beneficial information you will get versus the totally single point failure you introduce into the car's electric system. Some folks just can not let well enough alone.--Keoke- :laugh:

 

[GregW]

It only measures charging (or else it is hooked up backwards and only measuring draw, I'm not sure which, anyway it only shows activity to the plus side.)

Hi Tim,
Sounds like something is either wrong with the wiring, or the gauge. Does the gauge have -30/+30 or -60/+60?

 

[TimK]

The gauge is -30/+30 and is very sensitive/precise on the +side. It is measuring the output of the generator I'm sure -- it does exactly what Norman Nock says it should, (an initial high output after starting for a brief period, then settles down to 2 or 3 amps.)

I just rechecked and see that it is wired wrong, it is connected to the D terminal and fed by the yellow wire. That's why it only is showing the generator output.

Are you and Keoke saying that the ignition light is sufficient to tell you whether the generator is charging or not?

 

[TimK]

Well, I just moved the gauge wiring to the A terminal and it doesn't work at all. (The brown wire connected to one wire of the gauge and the other gauge wire connected to the A terminal -- I reversed the connections and neither worked.)

I have only one brown wire going to the A terminal, but the wiring diagram shows two; my two brown wires go to the A1 terminal. I wonder what gives. The A1 terminal feeds the light circuit on the diagram. I'll have to sort this out.

Well, I just sorted it out and found that the brown wire from the solenoid was coming into the A1 terminal instead of the A term. So now my gauge works in both directions.

 

[TimK]

It just occurred to me that the problem with the OD solenoid may not have been obvious if the high drain is offset by a high charge, wouldn't the ammeter show about zero?

 

[tahoe healey]

So, to get back to MY question, Would it be the brown wire at "B" that goes to the starter selenoid (yes, through the fire wall) using 10 gauge wire? Or am I way off base.

 

[TimK]

OK, OK, The brown wire that comes from the starter solenoid goes to the gauge wire (I used a wire nut to connect the wires). The other wire from the gauge goes to where that brown wire hooked in to the regulator. Both 10 gauge wires from the gauge go through the firewall. I'd use stranded wire. If the gauge reads backwards, reverse the wires on the gauge. Download a wiring diagram for the BJ8 so you can see how things should be. As I said, mine was wired incorrectly.

 

[tahoe healey]

Thanks, Tim. That was the definitive answer I needed.

 

[GregW]

Here's a little diagram. Interrupt the brown wire between the red hash marks.

 

[tahoe healey]

Hey, I like that. Electrical for Dummies.
Thanks, Greg.

 

[GregW]

Are you and Keoke saying that the ignition light is sufficient to tell you whether the generator is charging or not?

I won't answer for "The Man", but here are some of my thoughts. No.






To elaborate on that: Both leads to the ignition light are hot leads (the same polarity) regardless of + or - ground. The light goes on when there is a <span style="font-style: italic">difference</span> of voltage between the battery and the generator. So if (on a positive ground car) the battery side is -12 volts and the car is off, the generator side of the light would be 0 volts and the light would come on. Lets say the regulator is malfunctioning and is putting out 17 or 18 volts. That might not be enough voltage difference for the light to come on (5 or 6 volts), but it can fry a Pertronix unit which has a voltage ceiling of 16 volts. Incidentally, an ammeter wouldn't detect this, but a voltage meter would.

 

[TimK]

So, your bottom line is install a voltmeter rather than an ammeter?

 

[GregW]

I hope I'm not coming off as saying "This is what everyone should do". These are the things I've weighed and with that in mind, I installed a voltmeter. For the most part an ammeter will be fine. I promise I won't hold it against you (or Rich) for having one. :laugh:

P.S. glad you sorted out your wiring.