Not Happy

legion · 04-17-2008, 10:23 AM

Two years ago I redid the electrical system.

I had the alternator rebuilt, I replaced the main ground, I traced several voltage leaks (bad window regulator, a short in a light housing).

Yesterday I went out to start the car (I last drove it on Monday).

Nothing.

Grrr.....

hpservertech · 04-17-2008, 10:25 AM

Could of left a light on. It happens. jump it or charge the battery and see if it starts then.

legion · 04-17-2008, 11:27 AM

I'll check, but I don't think so.

Tishabet · 04-17-2008, 11:31 AM

Sometimes the cooling fan switch (located on your radiator) will fail and leave the fans on... had this happen to my car.

djnolan · djnolan's Garage

here is a sure way to find the problem assuming it is not intermittent.
Disconnect positive battery cable and separate all of the leads. Use an ohm meter on each lead to ground. any lead with a resistance under 2000 ohms indicates a short. if that is the case start popping fuses and the fuse that causes the resistance to change to a high value is the culprit. as an example a stuck relay will read 5 ohms. the clock reads 2k ohms. [numbers are all from memory] once culprit is identified check relays, switches, wiring, etc for problem.

legion · 04-17-2008, 06:59 PM

Yeah, I'm going to start that on Saturday.

I've been through it before.

I don't like it.

legion · 04-19-2008, 04:52 PM

Well, I put it on the charger for a few days.

Battery is reading 12.5 volts.

Density of battery water is good.

Car is drawing 10.4 milliamps at rest.

I did leave the AC switch on, but that shouldn't do anything.

zedsn · 04-19-2008, 06:26 PM

You may have a stuck relay or circut drawing current. You may have to pull each fuse and or relay one at a time to find the culprit. I have a drain on my 83 944 and it was easiest after I narrowed it down to put a disconnect switch near my ignition switch that would turn off and on the circut with the flick of the switch. I have heard that the alarms are a problem drawing current when they malfuntion and I believe Clarks garage can assist you more in that direction.

djnolan · djnolan's Garage

I think you are OK and do not have a serious drain at present. You would be drawing 0.5 Amps or greater if you had a stuck relay. However you could still have an intermittent problem, or a bad cell in the battery if it is draining down. did you load test the battery? autozone or someone will load test for free.

hpservertech · 04-20-2008, 09:23 AM

Remember to keep things simple. Sometimes it is just as simple as the battery being bad, they do go bad.

944 Ecology · 04-20-2008, 09:36 AM

10 milliamps is normal...

If it won't hold a charge, it's probably your battery. Try another.

SolReaver · 04-20-2008, 12:58 PM

hey Legion, check the Hlight motor by simply unplugging it and checking for a drain. I had a maddening drain that turned out to be from the hlight motor, or relay, or whatever it was..

That's all the advice I can give you. good luck chasing that gremilin.

legion · 04-20-2008, 05:08 PM

I let it sit overnight. The battery is reading 11.83 volts, still drawing an even 10 milliamps. The density of the water in the cells is still good.

I did leave on the AC switch and I was listening to the stereo (which I never do) when it drained.

hpservertech · 04-20-2008, 05:20 PM

The ac switch wont do anything.

Take the battery and have it load tested.

legion · 04-21-2008, 08:20 PM

Battery was reading 11.37 volts at the battery with multimeter.

When I turned the key to accessory, the volt gauge on the dash pegged at the bottom and the red light came on. It would not crank.

I took the battery to the auto parts store to have it load tested. After an hour of testing, the battery passed. When I got it home, it read 12.54 volts (not hooked up to the car).

I noticed most of the cells were low. I filled them with distilled water. I replaced the battery. I started the car successfully.

I put the battery back on the tender.

I am at a loss for what is going on.

djnolan · djnolan's Garage

first off the battery must be fully charged before it can be load tested properly. i assume it was charged if you have a tender or battery charger. adding the water should have helped as well. if all is ok with the battery, it could be bad connections somewhere in the electrical system. the voltage dropping severely under load is either a bad battery or a bad connection.

legion · 04-23-2008, 06:16 PM

Well, I took it for an hour drive today--both country roads and stop-and-go. I stopped at the store, bought some stuff, and left. I let the car sit for an hour while washing it and it started right up again.

I think the problem was the low water in the batteries.

I've noticed that my car wants a minimum of 12 volts to start. (This was true with the last battery that I got rid of two years ago.)

marky522 · 04-23-2008, 06:27 PM

With car batteries 12.45V is DEAD!!! 12.6 is fully charged.

Mark

legion · 04-25-2008, 06:19 PM

Well, it's continuing to work fine. I think the problem was the low water in the cells.

djnolan · djnolan's Garage

Hi,

I picked up an 87S on craigs list and wouldn't you know it, there seems to be a short runnin down battery! Using the aforementioned Ohm meter method, I separated all of the positive leads and one of the double red wire leads was reading 20 ohms. Popped relays and fuses until the culprit fuse turned out to be the radio amplifier.

With that fuse removed it is still reading a little high across the main positive cable around 60 Ohms. According to Ohms law I=V/R, that is a current draw of around 200 milliamps.

Question, what is off of the main positive batt lead that could be drawing this much current? I checked my 85.5 N/A and it reads 300 Ohms, so there is definately a difference with 80 ohms on the S. Is comething wrong or is the 944S have a different electrical system?

Any advice would be appreciated.