Dead Battery Follow-up

OK, I took my meter and here is what I have. With the car running and at about 3,000 RPM I am getting a reading of 13.56 volts across the battery. No power stuff on. At idle it is 12.15 Volts. No power stuff on. When I turn the car off and have everything off and key out of the ignition I disconnected the red lead and checked for amps in series of course. When the leads are connected the amps jump up to about .55Amp and there is some clicking going on under the dash, it sounds like, and then a moment later the amps drop to .1 Amp so something must be resetting and then the amps drop. I think that equates to 550ma and 100ma. I think. So, there it is. I didn't do the fuse thing since there are relays in there and I have no way to know if one is sticking and what it goes to and all that. Dealer stuff I think. Anything here look suspicious?

Bugsy

Reply to
Sluggo
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seems the voltage at idle is low, so battery is discharging when driving around in traffic. also voltage at 3k rpm sounds low, If you have another car or friends, check voltages under the same condition. Try measuring same voltage with lights on. You might have a bad alternater. There might be more info on the web.

Reply to
jjjsan

This is Turtle.

First the car idling normally and you can't get but 12.15 volts across the battery. Well flate out your not charging the battery at idle speed. Bad Alternator !

Secondly Running the engine at 3K RPM's and puts out 13.56 volts. You are charging the battery enough if you run the auto at that speed all the time to keep the battery up. Now when you start just getting 12.15 volts across the battery at a igle your dischanging the battery or just running off the battery and no help from the charging system at all. Bad Alternator !

Thirdly. The amperage draw on the system when the car is off and key is off. the auto theif system and other protection device are running all the time and needs power too. Now the .55 amps is pretty high for that system. The electric system does need power to run the computor to keep up with problem and recording the date and time of the problem. There is things that are still running when you cut the key off. Bad Alternator !

To test the system to see if it is the alternator or the battery which is bad. Here is how.

Take a volt meter on D.C. voltage and read across battery with the key off and door shut. You should get 12 to 12.6 volts. [ If you have 12 volts -- you have a week battery but still working. ] [ 12.6 volt or so --- a very hot battery. ] Anything 11.99 volts or less you have a bad battery.

Then take the volt meter and read across the battery while it is running or idling normally with most of the air and lights cut off. You should be getting

13.00 to 14.5 volts or 1 to 1.5 volts above the voltage reading you got from it while everything was cut off and just reading across the battery atleast or the least you can see and be good. Now most of the time you will see 14 volts or so at anything out of a good alternator and battery.

If you need to discuss it e-mail me and talk about it.

TURTLE

Reply to
TURTLE

charging appears insufficient. drain of 0.1 is far too high.. A good battery will have 12.7 volts available (charged and left to stand for a day or three) check and charge battery, refit and check how much current is being drawn with the alternator disconnected, should be a max of about 0.03, reconnect alternator and check again, should be max of 0.03 the high initial draw when you connect the battery is common to most modern cars. if you are not getting over 13 volts at idle (with a good, charged battery) then there is an alternator fault. ls400 alternator faults are common, particularly if you have had a leaking power steering pump.

mrcheerful

Reply to
mrcheerful

The drain of 0.1 A (100 mA) when shut down is way to high. This will be enough to flatten a healthy battery in 3 or 4 weeks.

You need to try and track down what's drawing the current - as I said originally, silly things like trunk lights, glove box lights are a common source of this problem. Otherwise, it gets more expensive - could be faulty alarm, radio etc. taking too much current.

Reply to
Bob Huntley

I am certainly no expert in this area, but as mentioned in another post, the receiver associated with the auto entry systems on these cars seem to take quite a toll on the battery. I switch it off whenever the car is going to sit a week or more. I have not experienced anything like the problems described, but I do know that I have had to replace the battery more often in this car, than other cars I have owned.

Reply to
Jerohm

That's about a full volt low. Should be around 14.2 to 14.4 at fast idle with nothing turned on.

Again, about a volt low. I would expect around 13.2 to 13.6 at idle with no load.

Your math is correct. Still a 100 ma static drain (to me) seems way high, like a glove box light or similar staying on. Nothing in the vehicle's electronics should have a 100 ma continuous drain. Remember with the hood open you have an engine compartment courtesy lamp. I assume you're disconnecting this when taking your measurements.

Alternator output (based on your meter) is out of spec. Static/standby current drain is (also IMO) about 10X higher than it should be... again per your meter.

At high idle with everything on (A/C blower motor, headlamps, glove box open, 4-way flashers on, all doors open, trunk open, stereo blaring, and someone sitting in the car operating the moon roof and power window buttons & door locks, seat motors, etc. you should still see a battery voltage of at least 12.0 to 12.6. This "full load" test may actually tell you more than the other tests you've done. In addition to alternator problems, I'd start looking for poor or loose connections in the charging circuit, between alternator and battery.

Reply to
New Owner

How do u switch off the auto entry system then? Cheers.

Reply to
Mad Fan

This is Turtle.

You know you hit that one right on the head about the power steering pump putting fluid on the alternator. I had a hose leaking and it killed my alternator with the fluid being put on it. It was not bad at all but just a little little bit did it. Them Alternator don't like to be spraied with earl.

TURTLE

Reply to
TURTLE

I thought I'd layout the procedure to check your battery and charging system. First, the battery has to be fully charged. Then take a voltage reading, which should be about 12.5 volts. Next start the engine and the voltage reading should go to 14.5 or so. This tells you the alternator is putting out. The last question is whether it is putting out sufficiently. So, turn on the headlights and see if the voltage stays about 14.5. If so, the charging circuit is OK.

Next you need to verify whether there is drain back from the battery when the engine is off. To do this, disconnect one of the battery terminals and place an ammeter in series with the battery terminal and the removed cable. There may be an initial surge of current, but should quickly stabilize to less than 50 milliamps. Make sure you close the car door and have all lights off. On some cars this reading can be as high as 80 milliamps, but any higher than this will cause a dead battery after a few days. If higher you need to remove fuses one at a time or check for leakback through the alternator. Sometimes something as simple as a trunk light switch can cause the problem.

Lastly, you need to check the battery to see if it can hold a charge and whether it can provide enough power to start the engine. To do this, again, the battery must be fully charged. Take a voltage reading (should be about

12.5). Disable the engine so it will not start. This is best done by removing the fuse for the fuel pump. Crank the engine for 5 seconds (use a watch). Wait 15 seconds and do again. Repeat this several times. You should be able to do this 10 or more times before the battery goes dead. If it fails sooner, the battery is defective (assuming you don't have excessive current draw problem with your starter).

Lastly again starting with a fully charged battery, disconnect either battery terminal. Take a voltage reading. Wait 12 hours and read again. Repeat this for two days. The voltage should no drop more than.1 volt. Reconnect the battery and crank the engine. If it cranks, battery is OK.

John Ackerman snipped-for-privacy@charter.net

Reply to
Ackerman

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