charging issues (WAS something's always "ON"!)

[maytag]

Hey!
I replaced the battery this evening, after having had to push-start the car a couple times this week. The battery was of unknown origin or vintage, so at first sign of suspicion, out it went.

But while I was hooking-up the new one, I got a small spark as I was placing the neg cable on the battery (pos was already attached).
SOMETHING is drawing amps, even when no key in and no accessories on, that I can find.

I'd love some ideas from y'all on how to trace this power-draw?

anyone?

[jimincalif]

Clock?

[jfrawley]

Newer type radio with a constant electrical feed to keep the memory and clock alive?

[lanciahf]

Touch the relays and see if any are hot. I had a Lancia once that the PO wired the radiator fan wrong and there was a constant draw.

Ralph

[majicwrench]

You will ALWAYS get a tiny spark, something about the diodes in the alternator, and that is NORMAL. And yes, clocks, and modern radios draw a very, very tiny amount, that will not cause problems. Now if the battery goes dead when it sits overnight, you have a problem that needs to be addressed. Need an amp meter to properly check draw.
Keith

[maytag]

You will ALWAYS get a tiny spark, something about the diodes in the alternator, and that is NORMAL. And yes, clocks, and modern radios draw a very, very tiny amount, that will not cause problems. Now if the battery goes dead when it sits overnight, you have a problem that needs to be addressed. Need an amp meter to properly check draw.
Keith

Well, the battery I just replaced WAS losing its charge overnight. But as I say, it was old, and a real unknown for me. I should probably KNOW how to use an AMP Meter, but I don't. Looks like I'll probably learn.

[majicwrench]

You can get a one ohm resistor from Radio Shack and use that for a make-shift way to check amp draw. I'll try to jog the old gray matter and remember how. I THINK you wire the resistor tween the battery post and cable, then check the voltage drop across the resister. If the post side of resistor has 12.5 volts, and the cable side has 12.3 volts, methinks you have a .2 amp draw. Ohms law. Jeesh it's been a long time, is this right??
Another way to do it, take a 194 bulb, and wire it between the battery post and cable. If it comes on you have a draw. A 194 bulb draws about .12 amp, which is enough to draw a battery down overnight, esp an old battery. Now start unpluggin fuses etc till light goes out. In my shop, one of the more common items is people wiring in their radios. The radio LED should be off when the key is off, not showing time!

Normanl parasitic draw on most older cars is about .02 amps. On modern cars with computer everything, you might see .04. Many modern vehicles put their systems to "sleep" after a certain time, and will drop below that.

You CANNOT use a voltmeter to check amperage draw, putting a voltmeter tween the post and the cable will always show voltage.

[maytag]

Rather than start a new topic, I just renamed this one, since it is so closely related so as to be the same processes for me..... and I really appreciate the help and ideas / thinking-through that y'all have provided.

So I spent a short amount of time on the car over the weekend, between fixing the A/C on my wife's car and then helping my soon-to-be-son-in-law work on his motorcycle....

In other threads I've chimed-in indicating that the charge light is on. I assumed I'd be buying an alternator. BUT: I got out the voltmeter saturday. Here's what I've got:

12.4v at the battery when not running.
12.1v at the battery when running (it's a brand-new OPTIMA battery, which always serves to confuse ANY electrical issue, as they mask a LOT of problems with how good that battery is)
BUT:
I've got 14.8v at the alternator when running. (Measured from the post on the back of the alt to ground)

SO: somewhere between the alt and the battery I've got a problem. I don't have a wiring diagram (I loaned-out my book and it hasn't come back yet), can somebody tell me what's between them? IS this a voltage-regulator issue? Where does the dash-light get its signal? I assume the alternator feeds through the regulator before charging the battery?

And what are the 4 wires connected to the back of the post on the alternator? and then there are two others with plug-in connectors; What are they?

thanks for all your help!

[jimincalif]

Strange. If the car starts you got good battery connections and good ground connections. On my car there is a wire from the positive post on the alternator to the starter motor. I'd check this out. Charge from the alternator flows thru this wire to the terminal on the starter which is connected via the large cable to the battery.

[maytag]

Strange. If the car starts you got good battery connections and good ground connections. On my car there is a wire from the positive post on the alternator to the starter motor. I'd check this out. Charge from the alternator flows thru this wire to the terminal on the starter which is connected via the large cable to the battery.

HMM.
I'll check this out.
Anyone know where the red-warning light is getting juiced from?

[majicwrench]

That big positive wire at back of alternator ( with 14.8 volts) can be run directlty to the battery +. As has been said, methinks it runs to the starter battery cable post originally. Problem is right there somewhere, nothing fancy tween that wire and the battery.

[ROOK1]

http://www.fiatspider.com/f08/viewtopic ... a&start=15

Page 2 just below my post may help you. My be a little different between years but cant be too much different.

[baltobernie]

Even inexpensive Volt Ohm Meters can measure current up to 200 mA (0.2 A), and no old car should be drawing more than that with the key Off. Select Amps on the scale, and attach the meter between the positive battery terminal and the positive battery cable.

What is the status of the charge light? Does it glow brightly with the key On and the engine Off? Is if Off (completely dark, not illuminated at all) with the engine running anything above idle and no accessories running?

To measure alternator output and voltage regulator accurately, there must be a load placed on the system. 12.1 volts at the battery with the engine running doesn't tell the full story. With the engine running at 1500 RPM, what is the reading? With the engine running at 1500 RPM and the headlights and heater fan On, what is the reading?

[maytag]

thanks Bernie.
The indicator light glows brightly ALL THE TIME, no matter the load or RPM.

And while I agree with you that measuring voltage at the batt doesn't tell the full story, what it DOES tell me is that the 14+ volts that I'm getting (at idle) at the alternator is NOT making it to the battery. If the alternator is making 14 volts, (at ANY rpm) but the battery isnt getting it, then I see a problem.

Or is there something I'm missing there? Granted, the ignition will take 'some', but i shouldn't see a voltage drop like that between the alt and the battery. should I?

[majicwrench]

No, you should not see a volt drop like that at all. YOu have a very basic issue tween the alt and the battery.