Power draw with heater on. Volts or Amps? (long) - Team Camaro Tech
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post #1 of 7 (permalink) Old Jan 30th, 07, 08:34 AM Thread Starter
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Jeff
 
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Power draw with heater on. Volts or Amps? (long)

I have a '69 Camaro coupe with a Vintage Air AC and heat kit on it. I have several questions about what I have and what I can do to fix some things I am seeing. I searched through the board and on MAD's website. My current alternator appears to be an over the counter unit with the power wire and 2-prong plug connector on top. Is this a 3-wire or 1-wire unit? I think it is 3 since a total of 3 wires are going to it.

These are the following things I am seeing

With the car idling out of gear I get 14.5v on my little gauge. If I press the brake pedal and the brake lights come on it goes to 13v. If I use my turn signals with the brakes on the gauge goes from 13v to 9v as the turn signals blink. If I have nothing on and turn on the head lights my gen. light starts to glow softly. As I press the brakes, use turn signals, etc it gets brighter as more things need power. Finally if I turn on my heater just by itself with nothing else but the engine running it pulls down to 12v, if I turn my head lights on it sits a 9v. From what I have read this all makes sense but I would not think all of these items would pull so much power. To top it off, if I am at highway speed I may get .5v more and thats it with the heater going.

I know I need to setup my headlights to a relay setup which I plan on doing soon. My main question is do I need an alternator that puts out more amps? I see 80, 100, 110, 120, and 140 amp alternators. I am not running any type of big stereo system or electric fans. The majority of my cars wiring appears to be original but in good shape and not cut up. I know that too many amps can burn up a wiring harness and I do not want that. Any info will be greatly appreciated. I can also provide pictures if needed.

Jeff
Current Vehicles: 1969 Camaro Z28 Clone

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post #2 of 7 (permalink) Old Jan 30th, 07, 11:05 AM
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Re: Power draw with heater on. Volts or Amps? (long)

Do this, check the connection between the battery negative terminal and the body of the car. On my 77 Nova this connection was poor and sometimes the blower motor was spinning fast, other times slow, sometimes the headlights were bright/sometimes dim.

Also too this little gauge you are using. Where is it getting power from and ground ?.

Jim

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post #3 of 7 (permalink) Old Jan 30th, 07, 12:40 PM Thread Starter
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Re: Power draw with heater on. Volts or Amps? (long)

The gauge is getting power from the fuse box, it is grounded to the dash chassis. The battery cables are fairly new but I will double check the negative connection and ground connection.

Jeff
Current Vehicles: 1969 Camaro Z28 Clone

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post #4 of 7 (permalink) Old Jan 30th, 07, 08:38 PM
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Re: Power draw with heater on. Volts or Amps? (long)

You definitely want to check ALL your electrical connections for main power. Remember, the "car's power" is the little leads coming off the battery cables, the big ones are just for the starter.

From how it's acting tho, I'd guess that your alterator has a bad diode. This will cause "reduced" output. It will charge, but not keep up with the load.

Verify that you have the right alternator (it is a 3 wire BTW, but there are 2 types) The original alternators were "external regulator" types. There will be a square black regulator mounted on the drivers side of the rad support. The connector bringing the 2 lil wires into the alternator will look like this: ||

Newer cars used an "internal regulator alternator" and these were often swapped into our old cars. There are certain wiring mondifications that have to be done for it to work right. The connector would look like this: - -

If you have the newer alternator, there are some things we should check to make sure the conversion was done properly.

If you have the original type, I'd suggest you get a new one at an auto parts store. Get the 61 amp, which was standard on cars with air conditioning, not the 37 amp standard alternator. You can always return it if it doesn't fix the problem.

Unfortunately, alternators with bad diodes almost always test good because they do still work.





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post #5 of 7 (permalink) Old Jan 31st, 07, 03:05 PM
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Re: Power draw with heater on. Volts or Amps? (long)

My vote is for a bad ground or bad power connection. Turn signals and brake lights shouldn't draw enough current to bring your battery voltage down that far.

Get a volt ohm meter and measure the voltage between the negative battery post and the dash ground. Then twiddle the lights as you were doing and see what the meter reads. The reading should be less than 0.10 volts I'd say.

You can do the same test by measuring the voltage between the positive post and the fuse block. Again, the voltage should be less than 0.10 volts (estimated).

If you see more than a few 10ths of a volt drop in either case, you've got a bad connection somewhere in the system. You can start moving your meter probes around in the circuit until you isolate the part where the voltage is dropping. Eventually that will pin-point the bad connection.

You may find it useful to extend your meter leads. I have a long piece of wire for that purpose. I've also been known to use an extension cord to extend the meter leads.

Dave
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post #6 of 7 (permalink) Old Jan 31st, 07, 09:08 PM Thread Starter
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Re: Power draw with heater on. Volts or Amps? (long)

I had class tonight but I did take a few mins to look under the hood and this is what I found. I have a later style alternator, the one with the - - plug on top. I did not see a black regulator on the drivers side of the rad. support, just the relay for the horns. I am guessing it is possible the wiring has not been done properly for the later style alternator.
You are right Dnult, I also need to go through the car, connection by conntection and see where my power is drain is coming from. Jim, if you can give me some things to look for as far as wiring goes or just send me a link to somewhere I would greatly appreciate it.

Jeff
Current Vehicles: 1969 Camaro Z28 Clone

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post #7 of 7 (permalink) Old Feb 1st, 07, 07:05 AM
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Re: Power draw with heater on. Volts or Amps? (long)

Jeff, there is excellent pics and info. in the sticky link at the top of this Elec. forum. Basics of Elec. check it out

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