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Triumph TR6 - how much amperage is enugh?

I started the quest to replace the alternator with a bosch unit, found one but havnt heard from the on line source if the order is confirmed. In the meantime, i read up on my ACR18 and it puts out 45 amps. Is 45 enough if i am running the electric rad fan (10 amps draw) stereo and driving lamps? The bosch ups to 55 amps and kicks in at lower rpm.

Whats the opinion out there..keep after the bosch or is 45 enough?

thanks

bob
Bob Craske

Bob,

The original alternator was rated to 28A. and I replace it with an AC-delco 35A. and later a 55 A. one. As TR6 does not have many accessories a 45A. is more than adequate, my two cents advice.

Cheers,

JGC
J. G. Catford

That depends on your cars own set up and acc's.
dk
DON KELLY

Don

I have added driving lamps (antique LUCAS) on a seperate relay and a stereo that pulls max 4 x 50 w, nominal would be 4 x 20. Other then that, pretty stock.

I am looking to add the electronic fan which will draw 10 amp maximum and that would be the final (dare I say it?) electrical load added.

tx

bob

Bob Craske

Bob,

You do not drive with fog lights on all the time and a TR6 is on the lean side for electrical needs. I drove a Volvo 242GT equipped with A/C, Fogs, rear window heater and électrical windows, for many years, with that 45A. alternator without any problem. This is more than adequate for a TR6.

Cheers,

JGC
J. G. Catford

Thanks JGC
Bob Craske

I agree with JGC that the 45 is adequate for the 6. The most notible response from people who have upgraded is the surprise they get when they come to a stop and the lights on the dash and headlights do not dim. The change is up to you.
dk
DON KELLY

Bob. While you are in the electrical mood and boosting the amperage output, don't forget to put in heavier gauge wiring to get this new found power to the battery. That in itself will likely keep the lights a little brighter and reduce the risk of burning up some wiring.

SID
Sid Turner

Sid,

Good point. I have replaced some battery cables on newer cars with much higher gauge cables to resolve starting problems.

Manufactureers use light gauge cables to keep cost and weight down, but it can restrict the current flow to the starter and other sparky bits.

Len
Leonard G Middleton

Moving from 45 to 55 I didnt think it was too much of a load issue, in the Gurus book (Dan Masters) he states that unless you add LARGE loads, stock wiring shouldnt present a problem since the main advantage of the higher output is the ability to provide a higher charge rate at low rpm/idle.

Still, Sid and Len have a point...which wire is the one to replace, the heavy gauge BROWN is quite the gauge already...is that the one to increase?

bob
Bob Craske

According to my "Book of knowledge" or my paper version of the CD that is going around, Dan Masters indicates in his GM Alternator Conversion article to "for 74-76: Remove the large Brown wire from the alternator to the connector on the main battery lead (cut the ends off or insulate and tie back) and run a new wire (8 Ga wire) from the alternator to the starter solenoid which also has the main lead from the battery. Support the new wire along the existing wiring harness with the liberal use of cable ties."

"To add large loads, connect them, properly fused of course, directly to the battery. The voltmeter will continue to work as before."

This all makes good sense to me, but I don't have easy access to be able to check it out, but I'm sure Dan has done this very successfully and that it's "tried, tested and true".

SID
Sid Turner

AWG gauge - Diameter Inches - Maximum amps for chassis wiring (single Wire, not Bundle)- Maximum amps for power transmission

0 0.3249 245 150
1 0.2893 211 119
2 0.2576 181 94
3 0.2294 158 75
4 0.2043 135 60
5 0.1819 118 47
6 0.162 101 37
7 0.1443 89 30
8 0.1285 73 24
9 0.1144 64 19
10 0.1019 55 15
11 0.0907 47 12
12 0.0808 41 9.3
13 0.072 35 7.4
14 0.0641 32 5.9
15 0.0571 28 4.7
16 0.0508 22 3.7
17 0.0453 19 2.9
18 0.0403 16 2.3

I have captured this table for those out there interested in knowing the capacity of their wires

thanks

bob
Bob Craske

Bob,

Thanks for some very useful information.

In addressing condcutors size there are two issues: heat capacity; and voltage drop.

As the rating indicates a difference in rating between free air (unbundled) and with other conductors, your table addresses the heating aspect. Do not want those wires to get too hot, melt the insulation and let out all that "genuine Lucas smoke". Hard to find NOS sources for gneuine Lucas smoke!

The table does not address the voltage drop issue. For example, if you decided to transfer some weight to the back of the car by moving the battery to the trunk / boot, you would not use the same guage size as the original installation. Otherwise the voltage drop might make the starter operation marginal.

Just another consideration if you are drawing significant current.

Regards,

Len
Leonard G Middleton

well, i may as well replace the feed to leverage the 55 amps...according to the guru (DM) i will cut the large gauge brown from the harness and run a larger gauge to the starter solenoid...can someone confirm that i am reading his instructions correctly?..

If so, since i dont want to cut the harness to shreds, i will just run a new wire on its own to the solenoid..i was looking for the best route and it appears that along the cross frame brace and along the passenger side of the engine bay is the best path?

thanks

bob (electrical plebe)
Bob Craske

This thread was discussed between 19/12/2005 and 22/12/2005

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