C4 Draining Battery

[84Stock]

I know you guys have seen this before but I can't find any recent posts. My '84 C4 is draining the battery big time while in use. New battery, alternator SEEMS ok (13-14v in use), but darn if it won't crank (<11v) after running, normally after several stops. Could be the old hot solenoid or starter, but it is not a slow crank like Chevy's I've had before, it is a clickey or dead no-go on the start attempt.

I've heard to put on an ampmeter (where does one get one of these outside of a weld shop) and pull fuses to look for load drain. I have not yet done a top-to-bottom review of the battery cable connections but I'm wondering if there are weak points I should look at first....Any Ideas?

A bit frustrated thinking about fusable links etc....

 

[BigRed]

Well it seems I would dig into the battery. Pull the neg lead off and bridge a test light between the pole and the cable. If it lights up major you've got a drain. (you can test the light by opening the door). Even better use a mutimeter to determine exact voltage, If that checks out your starter is prbly pulling WAY to many amps and simply overloading the system. In which case replace/rebuild the starter. Next up is heat! If the starter is getting SO hot that everything expands to the point of drawing 4 times as many amps your pbly going to have to get a heat shield going. (keep im mind when doing the draw test with the light/meter there will be a SMALL drain from your clocks and memory settings)

Pretty much all you have to know. Its VERY common on Ford 460's especially in motorhome (to much underhood heat).

 

[dburgjohn]

Old trick

One of the ways we used to check for key-off drains is to unhook the neg. cable and put a meter (or light) across it and the battery. Set it where you can see it and pull fuses one by one. When the meter drops (light changes) that circuit is pulling. This does not find the exact fault, but it keeps you from looking at the wrong wires.

Also don't forget that Autozone and others will test batteries and alternators for free.

 

[Ken Anderson]

Most likely it is the speaker relay or the I/C.

 

[WhalePirot]

Back up some and get simple

You might have a bad, new battery, but more likely poor (corroded) or missing leads, positive and/or negative. Despite all cables seemingly fine, some new, a $5 grounding strap, from frame to starter has cured my warm start sluggishness. You old cables may be internally corroded and unable to deliver full power (and ground).

Your after-start charging voltage should show about 14.3v, then drop to the 13s. Nominal battery voltage is 2.2x6=13.2. Higher indicates charging; lower discharging (my digital dash disagrees with my DVOM by a volt).

Headlight 'color' can be used to check current draw while starting. They certainly should not extinguish; only dim some (not Chinese food), unless the starter is drawing excessive current. Be real careful and know what you're doing if using the battery disconnect amperage check.

I am very wary of the 'expertise' at ANY chain supply place, but especially the battery sellers at Sears! A decent auto electric shop has the proper gear and could well save you money on unneeded replacement parts.

I'd certianly ensure the start circuitry and components are fine before complicating the process with pulled fuses. You did not mention a sitting/draining problem, but a warm/hot start issue.

 

[geekinavette]

I agree with everything WhalePirot said. Don't believe what the "chain" stores tell you about your batt/alternator. They do not place appropriate loads on the components to test them properly, at least last time I checked they didn't.

Your symptoms sound like a failing starter solenoid. Do the headlight test that WhalePirot mentioned, that'll tell whether its a low battery or failing starter solenoid.

Bill

 

[84Stock]

Update following testing

Wow. You guys know your stuff. Here's what I know now:

Bridging the Neg. terminal on the battery to the disconnected neg wire with my voltmeter showed 12v. A hefty bulb (tailight variety) in the bridge would not light unless I opened the door, and extingish when the timed circuit would comlpete. When I hooked up a tiny bulb in the circuit (trailer side lght variety) it would stay lit dim all the time.

Pulled all fuses one at a time to see if the little light or voltmeter it would go out and it did not. Leads me to believe the drain is directly wired outside the fusebox? I'm thinking security system, alternator or starter? Any other ideas before I go unplugging things at random?

Thanks again for your wisdom.

GFD

 

[geekinavette]

If you want to measure the current draw with the "small" light bulb then do this:

With the bulb in place, measure the voltage across the bulb itself and write it down. Then, remove the bulb and measure the resistance (ohms) of the bulb itself. Take the voltage you measured across the bulb and divide it by the resistance of the bulb, and that will give you the current flowing through the bulb.

If I remember correctly something like 0.01 Amps, or 10mA (milli-Amps) is considered normal.

 

[WhalePirot]

Methinks the GEEK is on the right track, with the solenoid issue. Always, though, finishing the testing before buying any parts.

 

[geekinavette]

Well I had that exact same problem with my car a while back. When it was hot hit the key and nothing but a very depressing "click". Replaced starter all was well.

I agree though, do the "headlight test". Its quick and easy and will tell you alot.

Bill

 

[84Stock]

Status: Drawing 1/2 amp (key off) as measured by 12v trailer light test lamp (ohms law method) between the neg. battery terminal and the neg. wire when disconnected. Pulling fuses with the lamp in place: no fuse dimmed or shut off the lamp. The new battery is fine. Alternator charging volts in range (14-13v). The lights-on starting test showed what I would call routine dimming (dim sum) while starting both cold and and at operating temperatures, many tries. Runs fine, but the 1/2 amp drain with key-off is scarey. Any ideas?

 

[geekinavette]

Did you give it time for the interior lights to turn off?

 

[never2nd]

Just an idea. I had an alternator in the car (86) that had a bad diode and allowed current to flow from the battery when the car was off. New alternator solved the problem. There is an article somewhere in one of these forums about the problem. Sorry I don't recall where.

 

[JonM]

Go out when its dark...see if you can see any light coming from the center glove box...my mercury switch was bad on my 84 and kept that light on.