c3 power drain

[Mark F.]

I had a bad alternator and I think that was the cause of my battery drain as the battery would go dead overnight. After I changed out the alternator I checked and the system is still drawing .75 amps. The only thing I know that is still running is the clock. Is .75 amps about right for a clock or do I still have another problem to search out. Unfortunately I didn't check the draw before I changed out the alternator.

Thanks

Mark

[Stephen L.]

Re: c3 power drain

I believe your clock is electromechanical, meaning it only draws current intermittently as it rewinds the spring. This cycle happens about every 2 minutes. I would continue the search for the problem.

Try disconnecting the voltage regulator.....

Did you check to see that the glove box light goes off when the door is closed???

Does your car have any aftermarket items that may be connected to continuous power... not controlled by the ignition off/on???

You might try monitoring the current draw as you remove fuses to see when the current draw quits. This will show you which circuit to check further. You'll need a wiring diagram of the car for this.

Good Luck

[Jeff G.]

Re: c3 power drain

I would start pulling fuses one by one to isolate each power group. I was going to say unplug the voltage regulator too but depends on which year you have. 69 has the regulator built into the altenator, and 68 it's separate. Aftermarket radio's commonly make use of a hot wire when ignition is off. Off hand, the other systems I can think of that can be powered when ignition is off are the exterior / interior lighting groups (incl. cigarette lighter), horns / audio alarm.
Jeff

[Jim T.]

Re: c3 power drain

Stephen the lighted middle storage compartment/glove box on my 68 was a problem in being active when the door was closed very early in its life.
It has been disconnected for over 30 years.

[Terry M.]

Re: c3 power drain

0.75 amp = 3/4 of an amp. This sounds high to me. I am more used to chasing these issues on more modern cars, and 3/4 or an amp is a large drain for a modern car -- I would think it is more so for an older one.

Do not assume the new alternator is without a malfunction. As others have said monitor the battery draw and disconnect the alternator (be careful not to short the hot lead to ground).

Remember, if you are trying to pull the fuses you will mort likely have the driver's door open (unless you are a Chinese contortionist). That will turn on the interior lights. Rig something to hold the door open switches closed.

Body shop supply stores (like where you can buy automotive paint, masking paper and tape) sell a clamp to go over the pin switch and hold it closed. Most cars no longer use pin switches in the door jambs -- so this tool, (like so many other useful antique tools) may be hard to find. If the guy behind the counter looks like he wasn't born when your car was new, you might have a challenge explaining to him what it is you want. See if there is an older employee or manager.

Keep us posted on what you find.

[Terry M.]

Re: c3 power drain

Jim,
Warping of the center door, and the subsequent illumination of the glove box light, is why they changed the center compartment from a plastic lid to fiberboard. Of course the constant pressure of the opening springs added to the force and heat causing the warpage.

[Jeff G.]

Re: c3 power drain

Terry,
By the way - 12V x .75A = 9 Watts (P=IxE). Aren't most interior lights around 8 watts? I think you guys are pretty much on target with your analogy...
Jeff

[Mark F.]

Re: c3 power drain

Tonight I'll start pulling the fuses. When I connected the amp meter across the circuit I got a fairly good sized spark and that is what led me to believe that more is going on than just the clock. The car is a 68 and I've changed out the voltage regulator also. The clock is a quartz movement now as the original clock wasn't working (now that's a surprise). When I turned the wiper override knob (on & off) the amp. draw didn't change. I figured that when turned on the override would increase the draw as I know that will run down a battery as well (that has me confused). I've verified that all the dome lights and rear compartment lights were off.

So in conclusion, .75 amps is more than the clock will pull so I've still got issues.

Mark

[Terry M.]

Re: c3 power drain

3/4 of an amp is a lot more than a quartz clock should draw. That kind of clock is not the electromechanical style that Stephen described, it will have a continuous draw; but it should be a lot less than 3/4 of an amp.

Remember there are a lot of items on our cars that are not protected by fuses. The alternator and voltage regulator are among them.

Good luck, and keep us posted.

[Jack H.]

Re: c3 power drain

(1) Rear storage compartment light is OFTEN a source of undetected current drain...

(2) YES! The clock solenoid only fires when the mainspring winds down, so you can expect a 'burst' of power drain every 90 seconds or so.

(3) Removing fuses and re-installing them is a good troubleshooting method, but it's not 'perfect'... Some circuits are un-switched and some are unfused (protected by fuseable links or unprotected altogether depending on model year).

(4) Interior lamps are rated in candlepower (CP) and that rating grasps the output power intensity of the lamp NOT its input power demand. These lamps fall typically in the 1-3 CP range which would put their output power in the .03-.06 Watt range.

The conversion efficiency of an incandescent lamp is pretty poor (electricity consumed vs. light generated). So, assuming something in the 10% range, you still get fractions of a Watt, but it might be close enough to explain the .75 Amp draw...

(5) Back to the clock...the periodic 'burst' power consumption profile applies ONLY if the clock is working properly! If the clock is 'dead', the mainspring's cocking solenoid could have 'welded' points and be drawing constant current depending on the ohmic contact efficiency of the weld. In a few rare cases, failed electro-mechanical clocks have been known to have created electrical fires by overheating their power line in the dash harness!

(6) Also, don't rule out other branch circuits like the cig lighter. It's possible the power lead wire has fallen off and is making spurious contact OR the insulation on the wire is 'skinned' and grounding out.

So, there are a number of tips... But, if you're not a skilled electrical tech, you can probably save time and $$$ by taking the car to a competent auto electric shop. My gut tells me they should be able to trouble shoot the source of the spurious drain in 30-minutes or so. Now, that does NOT comprehend the time and parts needed to actually fix the problem...

[Jeff G.]

Re: c3 power drain

Yes, .75A is likely a problem, I think much more than a clock would use. Please let us know what you discover...

[Mark F.]

Re: c3 power drain

After a process of elimination with the fuses nothing was showing up. For some reason I started playing with the ignition switch.

The problem (which I've had for years) was that I've been turning the key all the way to the left which I now assume is the accessory position. If I just turn it off to the straight up position and pull out the key the power drain stops. The clock is still running but only drawing .01 amps. Not sure what is drawing the amps in the acc. position, but guess that is a story for another day.

I feel like an idiot for not figuring this out over the last 5 years. I've always used a cut off switch on the battery. See what procrastination can do.

Yesterday I had put on an old alternator and it's sounding like the bearings are shot. Guess I better put the new one on. Ones problems never end.

Mark

[Terry M.]

Re: c3 power drain

In the accessory position the radio will play.

You have another issue, although it is not pressing, because the ignition key should not come out of the lock while the lock is in the Accessory position.

I like the low draw of the clock. Thanks for posting the solution.

[Jim T.]

Re: c3 power drain

Mark another known problem with my original owner 68 other than the glove box light is the windshield wiper switch.
If my 68 is not being used and the wiper switch is inadvertently moved from the off position and moved back to the off position the battery will continue to discharge.


To correct my 68's problem, I start my 68 and actually do a complete cycle of the windshield operation to on and then off.

This operation corrects the current drain. Last time this happened was about 25 years ago when I discovered the problem.

Wonder how many other 68 owners would have a current drain if they cycled the windshield wiper switch from off to on and the car was not in use?

[Mark F.]

Re: c3 power drain

I was not aware of the wiper switch but I've always known about the override switch causing problems. I'll watch the wiper activation switch in the future. Thanks for the info.

Mark