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AMMETER WIRING WITH ALTERNATOR


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Hi Folks, yesterday I renewed the battery on my '64 TR4 and the guy tested the battery under load [engine running, lights on]. It gave 13.8 volts so all well. However, the alternator conversion is causing the ammeter to give a significant apparent discharge. Does anyone have details of wiring which correct the ammeter reading to include alternator input? Pic attached of the ammeter with engine running and lights on.

 

Best wishes Willie

post-12067-0-68313000-1532519606_thumb.jpg

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The ammeter should go between the battery (pick up on the starter solenoid terminal) and everything else (including the Alternator O/P) except the Horns. (& starter motor obviously)

 

Bob.

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There could be two things happening here Willie.

The first is that the connections to the ammeter have not been reversed after the alternator installation so they are still set up for positive-earth. That would mean your apparent discharge is actually a charge. That is also not right of course but this can happen if the load (in your case the light circuit) is wired to the battery end of the ammeter instead of the alternator end. (As Bob says above)

 

The wiring is shown in this link but of course it is for a dynamo, so the battery and ammeter polarity will be the other way round for you and there will be no dynamo regulator :

http://www.advanceautowire.com/tr24a.pdf

 

This thumbnail shows what yours probably should be like:

 

post-7865-0-13562200-1532523074_thumb.jpg

Edited by RobH
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Have a look at Section J4 of the Technicalities CD, and also the article which James Christie and I wrote for TR Action 248 (March 2011).

Ian Cornish

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  • 1 year later...

Thanks to everyone who contributed.  I was looking to convert over to an alternator and the information was helpful.

A few more direct answers to questions I had:

The stock pully on the generator is a 4" pully with a 1" wide belt.  It's a 17mm opening, thus, will fit on most alternators with a 17mm armature provided the armature is long enough.  I converted my TR4 to a negative ground because, one, it's easy, and two, it makes all future work simple.  So, unless I guess you have a concourse TR4 I highly suggest you make the swap....it's really easy.

The GM 10SI and 12SI (12SI is a newer version) both have 17mm armatures, however that nomenclature is not a model number, just a series.  You have to find the correct wings to either fit the TR4 or make a slight mod to the upper support bracket to make everything fit.  Both have internal regulators so the TR4 regulator isn't needed.  You have a choice here.  You can either short out the state of the art regulator of the alternator so you can depend on the 1960's Lucas Electronic regulator, or, depend on the state of the art regulator in the alternator and remove the dependency on a 1960's Lucas regulator....I choose the more dependable method.

Once you make the conversion, the car's regulator (black box) really isn't needed and actually gets in the way.  However, you could still use it but it's more of a "bus tie" than a regulator.  Attached is the picture:

 

TR4 Regulator Rewire:

E: Not Used, disconnect

D: Connect single wire from Alternator to this connector, secondary wire in this spot goes to Generator Warning Lamp

F: Not used, rewire existing NG wire to A1 block

A: Not sued, rewire existing NW wire to A1 block

A1: Tie in NG, NW and NU wires into this block (just a bus tie at this time).

 

Now, you could remove the TR4 Regulator all together and just "bus tie" these wires together.  Electrically it makes no difference, aesthetically having the old Regulator in the car still looks cool, like an 50's sci-fi steam punk way but it doesn't serve any purpose other than that, or, as a simple bus tie to combine the wires into one, same as a wire nut.

 

This way, the warning light still illuminates depending on current draw, as well as the AMMETER and the amount of rewiring is limited to just a few changes at the car's regulator.  Pretty easy.

BTW, I decided to go with this Alternator, negative ground 100AMP model.  Yeah, it's overkill, but after installing a fuel injection system, plus new headlamps and Bluetooth speakers/radio, etc, I just didn't want to worry about electrical loads.

https://www.qualitypowerauto.com/catalog.php?item=306

 

 

wiring2.GIF

Edited by cinoaz
Change drawing for negative ground system
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Be aware that if you are using the dynamo pulley on an alternator it is not ideal, though it will work.  An alternator can rotate faster than a dynamo so usually has a smaller diameter pulley. This gives the benefit that the machine will provide decent charge at lower engine revs than would be the case with a dynamo. By using the dynamo pulley you are losing that. 

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