View Full Version : Alternator conversion

05-11-2006, 01:35 PM
I have a alt. conversion kit for my TR4. It puts out about 70-80 amps. Can the wiring take it?

05-11-2006, 03:20 PM
it's not the amps it's the draw.

with everything else being the same as stock then yes. If you splice in a hotplate for the back seat then no.

05-11-2006, 03:56 PM
The battery is the big provider of the system with several times more amperage than a generator or alternator. Jim is correct, the operating accessories and lights will be absolutely fine. Think of the power plant your house is ultimately connected to and your lightbulbs do not blow.
However, if the battery is low it will ask for more from the charging unit and if that unit is upgraded sufficiently it could be asked for more than the charging system wiring can tolerate. Your first clue could be the smell of the insulation on the wiring getting hot.
Hopefully someone has expeirence and can answer your question directly. I do not know the capabilities of the system or generator to compare against the alternator.

05-11-2006, 04:53 PM
There are several things to consider...

1. If you haven't converted to negative ground, you must do so, as the alternator is made to run negative ground.
2. If you have a 30 amp ammeter, you will have to consider what to do with that, as there are times when the charging rate may exceed that. You can eliminate it, put in a higher amp ammeter, or you can shunt it so it will read amperage by approximately half.
3. I would make sure that the main output wire from the alternator going back to the battery is at least 10 gauge. It's usually attached to the post where the fat battery cable attaches to the starter.

If you need any info on shunting the ammeter, it can be found at Advance Auto Wire's website under the instructions for putting in Dan Master's wiring harnesses.

05-11-2006, 05:08 PM
Less is more. The less distance you have to run with a loaded wire, the better off you will be. I never did like idea of running my 66 amp alternator the long route, through the starter solenoid lead. Instead, I chose to run a totally separate 8 gauge wire from the alternator directly to the battery by using an appropriate double positive battery lead. Nice and neat and less wire. Anything that pulls lots of current that is not stock should be run under a totally independant circuit, IMHO. I ran my halogen fogs though a relay using an independant circuit, as well as my electric radiator fan, also relayed and on it's own circuit.
Early on in my LBC adventures, I remember buying a one-size-fits-all fog light setup from a speed shop, wired it up through the stock harness, and fried the whole thing.


05-11-2006, 05:58 PM
Thanks guys for the quick response, All good stuff.
I look forward to our chats.

05-11-2006, 06:15 PM
After checking out a few DC ampacity charts, I have to agree with TR6BILL that 8 gauge wire would be more appropriate. 10 gauge is good for about 50-55 amps and 8 gauge will handle about 70-75 amps. Also, running the wire to the battery directly is a better idea, as it eliminates one more connection and its longer length in the hot area of the starter.

05-11-2006, 10:44 PM
To add to all that good advice;(with a 60amp GM alternator)(the factory Lucas is 45amp)If your battery is dead ALWAYS take the battery out of the car & recharge.Don't try to start the car in gear,& charge the battery by driving it you'll most likely fry EVERYTHING.Halogens using an OEM alternator will overheat the antiquated wiring,especially when alot of amps are shunted through the 3 wire headlight switch,that switch takes a big hit. /ubbthreads/images/graemlins/nonod.gif /ubbthreads/images/graemlins/nonono.gif

05-12-2006, 09:57 AM
Like I said... everything stock and you're OK but I like the idea of uprating the connection to the battery directly. That's a great idea if I ever go the alternator route.

"myspitfire" makes a good point about upgrading anything on the car that increases the draw - If you put in fancy lights or a thumping stereo you don't want to be running it through existing leads and particularly those existing switches. In the Halogen example you'd be very wise to wire the switch itself to a new relay that will handle the load through new heavier wires. The switch then only has to carry the load for the low-amp coil on the relay (which is significantly lower than even stock lights)

05-12-2006, 10:02 AM
Advance Auto Wire's website , do you have the URL,
I tried google and could not find it.....thanks


05-12-2006, 12:06 PM

Yeah, for some strange reason googling Advance Auto Wire does not bring it up. /ubbthreads/images/graemlins/hammer.gif

05-12-2006, 12:27 PM
I'd suggest ditching the amp gauge and installing a volt gauge when you go to an alternator.

05-12-2006, 08:06 PM
I am not sure I understand what is meant by "connection to the battery directly" Can someone tell me more?

Andrew Mace
05-12-2006, 08:20 PM

Yeah, for some strange reason googling Advance Auto Wire does not bring it up. /ubbthreads/images/graemlins/hammer.gif

[/ QUOTE ]But Googling "Advance Auto Wire" (with the quotation marks) does! /ubbthreads/images/graemlins/smile.gif

05-12-2006, 08:34 PM
The big hot wire (red) on the stock harness goes directly from the positive post on the battery to the starter solenoid and has a christmas tree of brown hot wires that feed from the alternator and feed to the harness. For whatever reason, many who convert to higher amp alternators, like the Bosch from the Ford Fiesta or a Delco or Delco-style from a late sixties and up Chevy, will run the big wire from the new alternator to the starter solenoid, mainly because the screw eyelet is already there for the connection. Others have found that it is just as easy and better to shorten this "hot" wire and go directly to the positive on the battery. I went to a local NAPA and bought a double hot wire that had the lead clamp connector made up for the battery positive, the large one (probably 6 gauge) was professionally spliced into the harness (using very heavy copper crimp connectors specific for heavy wire and soldered) and the other tail (8 gauge) went directly to the alternator. Saved about 2 feet of unnecessary wire and didn't put another connection to worry about down on starter where I couldn't check on it.


05-13-2006, 06:40 AM
Thanks, Very good. I will follow your advice.