Mysterious Power Drain

My battery has been draining to nothing in a matter of hours ever since I changed alternators and voltage regulators. The mysterious part about it is I tested the car for shorts by placing a test light between the disconnected negative battery terminal and a ground on the body and found no shorts. The car really has no electrical accessories and nothing is being left on, yet the battery is still dead a few hours after it is parked. The only thing that has changed is the alternator, alternator harness, and voltage regulator. Everything was hooked up according to the wiring diagrams and it charges at a steady 14V when running. Anybody have any ideas what is going on? I'm starting to think this car is posessed. Thanks.

 

A test light hooked up like that dont tell you anything. Test lights work on voltage, not current. Put an amp meter in series with the positive or negitive cable and battery post. Then start disconnecting things untill the reading stops.

 

pull the bulb out of the dome light, see if that helps

 

I know this is probably the first thing you looked at, but did you check the battery?? My car has a slow drain (takes a coupla weeks to die) so I just disconnect the negative cable. Good Luck!!! Preston

 

In order for you to use a test light to detect a battery drain, the light must be connected in series with the battery. Simply placing the test light between the cable and a ground will not work as you have effectively removed the battery from the circuit.

Disconnect the negative battery cable and connect the test light to the cable and the probe to the terminal of the battery. If the battery is charged (voltage present) and there is current flow present (your drain) the bulb will illuminate.

Also keep in mind that the drain may be fixed temporarily when you disconnect the battery due to resetting the faulty component. In this case prior to disconnecting the battery you can connect the test light to the cable then place the probe on the battery terminal then lift the terminal from the battery up the shaft of the test light probe. Placing a little electrical tape on the shaft of the probe will make this easier. Another set of hands help to.

Good Luck!

 

send the regulator back. get a new one. maybe the cut-out relay in it is bad.

 

I'm with scott..I had the same prob and went through 3 voltage regulators before I got a good one. Aftermarket regulators are crap. It could also be the batteries inability to hold a charge, typically the sides of the battery will appear slightly swollen if this is the case.Without something to detect current (ammeter or amprobe) it could be difficult to pinpoint. Good Luck!!

 

The proper way to test for voltage draws is to check it with an ammeter (clamp style) and start pulling fuses. The ammeter will indicate which circuit is drawing. The Mav should be easy to find this kinda problem. Now some of these newer cars I deal with that have 3 fuse boxes and what seems like circuits within circuits well lets just say I do this Amps is the flow like water which is what you will be looking for. Forgot to add things not on a fused circuit you will need to disable to test(ie remove ground or power source) Good Luck

 

I have to reverse my statement above. Putting a test light in series between either cable and the matching battery post, will will cause the test light to light if current is flowing due to a known or unknown source. But, you are also putting the test light in series with the problem that is draining your battery. Since current is the same through any load in a series circuit, if your battery drainning problem is drawing more current then the light is designed to use, you will blow the bulb. Test lights probably draw less than a few milliamps.

 

Yeah, I connected the test light in series with the battery. In other words I removed the negative battery terminal from the battery and connected one end of the test light to it. I connected the other end to the negative post on the battery. The light didn't light up, which tells me there is no short to ground, thus no current drain from that. I suppose you could either do that or connect the other end to the engine or body directly and it would do the same thing as the battery is grounded to the engine block in my car. I also connected the light across the battery after the test and it lit up, so the bulb wasn't blown.

I'm leaning towards the theory about the voltage regulator draining my battery. But there are a couple other options too. My ignition switch has been acting a little weird lately and a couple hot wires coming through the firewall have been going on and off at random times lately (one of them happens to be the hot wire running to me ignition box which is why it wasn't working!!). I'm not quite sure how that would drain my battery, maybe the switch is still alowing current to flow to all the accessories even when the key is off.

Another possibility is that I could have possibly fried the battery and it just won't hold much of a charge, as the system was charging at 14V, which seems a little high but I would think it would still be ok. I jumped the car last night and drove it around for about 20 mins and parked it. I came back about half an hour later and the battery was stone dead, that kind of makes me think the battery is toast, but that's a little weird since it was fine before I changed alternators and voltage regulators.

 

I think a new battery might solve the problem. (But then again, thinking gets me into a lot of trouble) At least at the parts house, they can test the battery and see if it will even hold a charge. Just a thought, and again, Good Luck!! Preston

 

Charge the battery overnight and take it to the parts store and have it tested. Places like Autozone and Part America will test them for free. While your at it pull the regulator and have them test it also.

 

REPLACE THE BATTERY! Cold weather does weird things to them. Your alternator sounds like it's charging alright, but your battery will not accept the charge.

 

I am with 1badmav on this one. That is the best way to troubleshoot electrical problems. That is where I start.
Dan

 

if it drains in a few hours then charge it up and let it sit for a few hours (unhooked) and see if it drains...if not it is not the batt...frank... good luck