Author Topic: 1980 TA electrical current draw  (Read 859 times)

5th T/A

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1980 TA electrical current draw
« on: May 07, 2021, 10:26:40 AM »
This may not be useful, but I thought I would post it anyway.
While upgrading the engine on my 1980 TA, I replaced the alternator. Initially I had planned to use the factory GM 15SI that came with the car. Unfortunately the stock alternator brackets on most Pontiac engines have the smaller bolt spacing used on 10SI and 12SI alternators. Complicating things a little I added an EFI system increasing the cars current draw. After reading Tony Candela's book " EFI Conversions" I decided something more powerful than a 10SI or 12SI alternator was needed. My research found most alternators are rated at cruising RPM, not at idle. So a 70 amp rated alternator may only provide 35 amps at idle.

This is the current draw of various devices in amps.

Courtesy lights         2.0
Parking and dash lamps   6.3
Headlights Low         14.8
Headlights Hi         16.8
Brake lights         7.7
Horn            9.2
Trunk light         .9
Rear window defroster      14.8
ECU and electric fuel pump   16.0

AC/Heat blower
Low            5.8
Med         8.7
Hi            12.5
MAX            17.1



This is a possible scenario sitting at a stop light on a cold night.

Headlamps         14.8
Brake Lights         7.7
Defroster blower max      17.1
Rear defroster         14.8
ECU             16.0

Total amps   70.4

1980 T/A with a Pontiac 461

Gone but not forgotten;
1973 T/A 455
1975 T/A 400
1978 T/A W72
1982 T/A cross fire injected

Two wheel toys;
2014 Harley Ultra Classic Limited
2013 Honda CB1100
2010 Yamaha Vmax
1982 Yamaha Seca 750

aussieta

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Re: 1980 TA electrical current draw
« Reply #1 on: May 07, 2021, 05:39:36 PM »
i fitted a mechman alternator, has twin rectifier plates
https://www.mechman.com/alternators/aftermarket-bracket-applications/170-amp-racing-alternator-for-1963-1985-gm-black/
with efi, thermo fans, big stereo, ac, etc, etc, voltage never drops below 14.3 at idle
1978 Y84 W72 WS6
A Camaro looks like it could kick your ass.
A Trans Am looks like it's coming over to do it

5th T/A

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Re: 1980 TA electrical current draw
« Reply #2 on: May 08, 2021, 08:47:24 AM »
Aussieta,

Other than the color I think that is the same alternator I used. Currently it’s more than enough for me. I wanted some reserve should I need to go with electric fans.
1980 T/A with a Pontiac 461

Gone but not forgotten;
1973 T/A 455
1975 T/A 400
1978 T/A W72
1982 T/A cross fire injected

Two wheel toys;
2014 Harley Ultra Classic Limited
2013 Honda CB1100
2010 Yamaha Vmax
1982 Yamaha Seca 750

Re: 1980 TA electrical current draw
« Reply #2 on: May 08, 2021, 08:47:24 AM »
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