Visit our Twitter feed for more great content
TRExp

TR6 Tech Forum

Alternator upgrade

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

LFMTR4 Avatar
LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
Well I went with a 55A and the ammeter was usually pegged to the + side and smelling burnt before I changed it. I can imagine what a 95A will do after some starter cranking.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
bikeboy Avatar
bikeboy Silver Member Ian Fox
Lara, Victoria, Australia   AUS
In reply to # 1590321 by LFMTR4 When I upgraded my alternator, I swapped the ammeter to a period correct Smiths voltmeter off eBay. Cost me $25.

This is what I plan to do as well. Unfortunately, it's costing a bit more than that. Because I have the early gauges, the profile of the bezel is different, and I've had to also get an old fuel gauge to pull apart to swap the bezels. Thanks for all the info guys.

LFMTR4 Avatar
LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
Ian,

I had the same problem, try eBay UK. That's where I got mine. As you probably already know, ask the seller if they will ship internationally before bidding as a lot wont.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

Attachments:
IMG-20130331-00079.jpg    45.2 KB
IMG-20130331-00079.jpg

nync Avatar
nync Glenn Meteer
Charlotte, NC, USA   USA
Thanks guys for the answers. The original ampmeter works fine so far but I will check out the voltmeter. It jumps left (discharge side of the scale) when starting or turning on the headlights, but then it returns to the center of the scale after a second or so.

bikeboy Avatar
bikeboy Silver Member Ian Fox
Lara, Victoria, Australia   AUS
Final piece of the puzzle. Had to buy a sacrificial fuel gauge to get the correct bezel, but it's all good now. Scale is reversed compared to the 30amp unit, but clearly marked. I do plan to run an extra (thick) wire back to the battery, but I need suggestions on how to connect it without hacking the harness?


Attachments:
IMG_1871.JPG    72.2 KB
IMG_1871.JPG

IMG_1872.JPG    67.9 KB
Sign In or Register to view this photo
bikeboy Avatar
bikeboy Silver Member Ian Fox
Lara, Victoria, Australia   AUS
So, it turns out my new alternator has an empty B+ screw terminal on the back that seems to be redundant if the spade connector is being used. Is this where I could possibly connect my additional wire back to the battery? It seems to be charging the same rate as the factory terminal, and has the same voltage at rest as as the brown/white.


Attachments:
altRear.JPG    58.3 KB
altRear.JPG

LFMTR4 Avatar
LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
Well....that was the one I was referring to that you said you didn’t have in the PM. Yes, that’s where I attached my second wire. Just make sure it’s protected and can’t be shorted to ground.

bikeboy Avatar
bikeboy Silver Member Ian Fox
Lara, Victoria, Australia   AUS
In reply to # 1594527 by LFMTR4 Well....that was the one I was referring to that you said you didn’t have in the PM. Yes, that’s where I attached my second wire. Just make sure it’s protected and can’t be shorted to ground.

I just thought it was redundant because of the spade connectors? I guess it's part of the 'universal fitting' requirement (I think it's a Ford unit?). That's good news.

thanks mate.

bikeboy Avatar
bikeboy Silver Member Ian Fox
Lara, Victoria, Australia   AUS
So, I fitted the additional 30amp lead from the B+ terminal back to the battery, and the ammeter no longer registers. The battery is being charged at 14.4V, but nothing on the ammeter. I disconnect the extra wire, and it's all good. I think I'd rather see the ammeter working, so I think I'll disconnect the second charge circuit. Disappointing, but unless there's something I'm doing wrong, I'll not bother with the 'just in case' wire. Either that or swap the ammeter for a voltmeter?

cheers

LFMTR4 Avatar
LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
The “just in case” wire can keep part of your unfused loom from turning into a smoking mess just do the math and look up what the stock wire can handle safely. I went with the voltmeter and I prefer looking at voltage rather than a plus and minus. Keep in mind that you could now be sending a lot more current through that ammeter.

bikeboy Avatar
bikeboy Silver Member Ian Fox
Lara, Victoria, Australia   AUS
Thanks Lou. The more I think about it the more I'm inclined to fit a voltmeter, along with the extra wire. At it's peak, just after starting, the meter reads about 15amps, then quickly settles down to just past the zero marker. I understand that would likely increase as more is demanded of say a cold start that drags on a bit, but until I can source me a voltmeter, I'll just have to be careful. Normal running demands aren't an issue.

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
If you want the ammeter to work, your second wire needs to follow the original charging circuit through the ammeter.

Personally, my approach was to not bother. I've run without the extra wire for going-on 35 years now, and had no trouble at all (on my TR3 and TR3A). The typical ampacity charts are VERY conservative, and assume conditions like multiple wires in the same bundle all carrying the max, the bundle in an enclosed space surrounded by flammable materials (paper and wood), continuous duty and so on.

GM electrical systems are usually pretty reliable; mine has a 130 amp alternator feeding roughly 8 AWG wire.

The ammeter is a different question, though. Mine did not seem to like being banged against the peg every time the engine started; so I added a shunt across the back of the ammeter. Just a length of relatively small copper wire (I forget whether it was 14 or 12 AWG), with the length chosen to get half the usual reading on the gauge, and coiled up behind it.


I prefer an ammeter over a voltmeter. In addition to being original (on my cars), it tells you things a voltmeter won't, like are the headlights on and do the brake lights work. It tells you what the charging system is doing right now, as opposed to what has happened in the past. Just one example, if your voltmeter reads 13 volts, you don't know if the battery is actively being charged, or the voltage regulator is getting flaky.

They also tend to be less accurate, just because they sample the voltage after it has gone through the ignition switch and so on. I put a lot of work into calibrating the voltmeter on Stag #1, only to find that it still read 1/2 volt or so below actual battery voltage. And the difference wasn't even constant, it read lower when the heater blower was on.

Ammeters can be inaccurate too, of course, but really all you care about is "Is it dis/charging a little, a lot, or not at all". It doesn't really matter if it's 20 amps or 30 amps.

IMO, YMMV, etc.



Randall
56 TR3 TS13571L Once and future daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild



Edited 1 time(s). Last edit at 2019-02-13 02:34 AM by TR3driver.

bikeboy Avatar
bikeboy Silver Member Ian Fox
Lara, Victoria, Australia   AUS
In reply to # 1596269 by TR3driver If you want the ammeter to work, your second wire needs to follow the original charging circuit through the ammeter.

Yeah, that's what I thought Randall. Too clumsy with thick wire, heavy-duty connectors, and lack of wiggle-room around the meter. I'm really torn :-( I prefer an ammeter and the 60amp unit seems to be coping well, and note your positive experience. I'll get around to tossing a coin one day I reckon ;-)

cheers guys

LFMTR4 Avatar
LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
For most the real draw comes after a dead battery. After jumping or pushing off the car, the alternator will try to put out as much as it can for an extended period as it replenishes the battery. That's when things will get hot. The other situation I have run into is in rain at night if you get caught in it with the defrost, lights and wipers going, its a bit of high load. As long as you are mindful of that...

Me, I prefer not to take the chance so I ran the wire and fitted a Smiths voltmeter. I have a lot of time and $$ in the car and it will pass along to my son one day and I don't want him having to deal with that. But hey, your car, your choice just don't tell your insurance company.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions




Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster