Did I pick up 5hp (alternator drag?)

[cudabob496]

Okay, I have the alternator output going to the 12V starter relay post, and the rest of the electrical needs coming off the relay post. When cruising down the road, the autometer ammeter that is supplied by the alternator reads about 8 amps continuous, which is what my car is consuming in order to work. If I click on a turn signal, it jumps up and down by 2 amps, if I click on the headlights, it jumps to about 18 amps continuous. If I turn on my electric fan, if jumps up by about 10 amps. I'm probably gonna replace the 30 amp fuse in the wire from the alternator with a 40 amp fuse. Its nice to be able to monitor the electric load while driving. Thanks for the help everyone! What mod/project next? Ideas are welcome!

[Justins72]

Man Im still confused  , anyone have a picture or diagram on how this is suppose to be hooked up

[cudabob496]

Justin, tell me what you want to do first.

[Justins72]

the whole thing haha. is it just adding a bigger wire from the alternator to the starter relay? or is there more to it.

[cudabob496]

That's the main part of it. By adding a 14 guage wire (with an inline fuse of at least 30 amps) from your alternator to your starter relay 12V post, you bypass the firewall bulkhead connector, and therefore make your electrical system more reliable.  Do that first, and see how she runs. Keep the existing wire from your alternator output in place, as it will still power some circuits in your dash/ignition.

[Katfish]

Cudabob,

I'm going to add relays to other circuits.  Any way you could list the different current draws of the circuits,
now that you have that accurate set-up?

Lights, running lights, turn signals, brake lights, blower motor, horn, etc.

I know you did a couple, I'd like to find out all the draws so I get the most bang for my buck.

[cudabob496]

No blower motor. Brake lights were between 1 and 2 amps, turn signals 2 to 3 amps each. I'll do horn and lights next time I'm out, and let you know. Keep in mind this is a 35 year old electrical system that's seen better days.

[Katfish]

Thanks, mine is old as well, so it's a good comparison for me.

Appreciate the help!

[cudabob496]

Well, I took the beast out today. Headlights drew about 10 amps. Horn about 2 amps, and running lights about 2 amps.  My electric fan draws about 10 amps, but has a 20 amp initial surge. Maybe partly because the blades are windmilling backwards before I initially start it. What's the benefit of relays over just inline fuses?

[Got JOB]

Relays carry the amperage from the source to the device. The switch becomes the trigger that activates the relay and the device. If your fans are not on a relay then the total amperage goes thru your switch. With relays mounted close to the device the current path is shorter also. I would still use an inline fuse for the device.

[cudabob496]

That makes sense, but is it a problem for the current to go through the switch, if the switch is rated for the current?

[Katfish]

Standard auto relays are rated up to 40A,  here's a good deal that I used, they include the wiring harness.

http://cgi.ebay.com/5-PACK-12V-DC-30A-40A-Bosch-Style-Relay-Socket-SPDT_W0QQitemZ190127731384QQihZ009QQcategoryZ50552QQcmdZViewItem

The problem with our old cars is resistance increases with age, corrosion at all the interconnects.  As little as 1ohm on a circuit that draws 5A will drop the voltage 5V.  The relays only draw 0.15A.