F451

Hey guys,

My '85 auto is showing the symptoms of a dead battery. Go to start it, it turns over a bit, if it does not start right away, the battery appears to drain, as the motor turns over slower and slower with each attempt to start, until I get the classic "click, click, click" from the starter, and no more turning over.

I've checked the batt fluid level - its fine. I've charged up the battery a number of times, and then it will turn over, and sometimes starts. Other times, it will slowly die as described above.

I checked the cable connections at the battery and they are fine. I cleaned the battery ground strap connection to the body, there was a bit of corrosion, but nothing substantial. I took sandpaper and steel wool to both the cable end and the mount area and got them spotless, and reconnected the ground cable. No change in symptoms.

I next took some readings with my multimeter to check voltage in a few spots, and this has me a bit stumped.

FYI: I set the multimeter to the DC volts section, on the "20" position. Not sure if this is the correct setting for measuring voltage on the car, so please chime in if this is not correct. And I connected the red wire to the DC volts input, and black wire to the common input on the MM.

Readings:

No start condition:
At Battery posts, car off, key in off position, not cranking: 13.8
At jumper post in hood, car off. key in off position, ground to cross brace bolt: 13.6

Car Running after jump:
At battery posts, at normal steady idle: 15.5
At battery posts, at steady 3k rpm: 15.9

At jumper post in hood, ground to cross brace bolt, at normal, steady idle: 16.15
At jumper post in hood, ground to cross brace bolt, at steady 3k rpm: 16.18

Q: Are these readings while the car is running correct? They seem high to me from what I have read during my searches.

Q: Would it be beneficial to take a reading at the starter as it seems my battery readings are within the correct range?

Q: Do these symptoms and readings point to a failing starter?

I'm considering buying a new ground strap and battery just for the hell of it, but the readings do not look like it is either to me.

Any tips on further diagnostics would be appreciated.

Thanks guys!

Ed

F451

Humm, just occured to me that I have not taken any readings from anywhere when the car is cranking over, or is attempting to turn over.

Would that be beneficial, and where would be a good place to take those readings?

Thanks.

mark kibort

sounds like you need a new meter. voltage should never be over 13.8v when running, and normal voltage for just the battery is 12.5 to 12.7 fully charged after sitting for a while
good idea to see what the voltage drop is when you start.

F451

Yes, I was wondering about that. Either I am not using it correctly, or its defective. I'll have to see if my neighbor has one and compare the two.

And I also think I'll have the battery load tested. That should tell me the condition of it right there. That way I can either rule it out, or if its bad, replace it and see what happens then.

Thanks.

Mrmerlin

check for a current drain it might be coming from the alternator, usually if the chage voltage is over 14.7 or so it indivcates a problem inside the alternator or regulator it could be a diode as well, If the alt is causing the slow drain your best option is to replace it then do a voltage drain test

Alan

For the primary question you are asking checking the voltage while cranking would be beneficial - however you readings are not consistent... so you may need a new DMM (or a new battery in the one you have...?)

However also understand that the voltage regulation will not work very well on a car with a badly functioning battery.

You almost certainly need to get the battery replaced - have it load tested at a store first. The starter is almost certainly not the problem.

Don't mess with it any more just take the battery in to be tested.

Then redo your tests with your new battery (prob!) and see what you get with your (possible replaced or improved) meter...

Alan

Charley B

Replace Battery.

jon928se

You are using your meter correctly. Your meter is telling lies. Buy or Borrow another meter and recheck the voltages.

Battery should read around 12.5 to 12.7 V when fully charged, and measured say 1 hour after charging has stopped. (It may read higher right after charging.)

Then recheck the running voltages. should be no more than about 14.1V.

Also clean the positive connection to the starter, the bundle of positive connections behind the jump start post and clean or replace the engine to body ground strap - above the Motor mount on the drivers side (Starboard or right looking forwards) . The voltage differences (if your meter can be trusted at all) between charging volts at the battery and charging volts at the jump start post look a bit high.

heinrich

Ed try the one from the S4. That will answer all your questions I think for the car's alternator to be bad that would be highly unlikely given that the car is practically brand new in every way. Possible but .... and if I can assist, please let me know. Too much cranking likethat will foul the plugs big time.

F451

Great, thanks for all the great tips guys.

H, I had meant to put the S4 batt in the '85, but just did not get around to it. If the car starts up normally with the S4 batt, and runs normally, then for sure its the batt.

A simple check that I should have done in the first place!

And I need to check those grounds anyway, been meaning to do that on both cars, so will do that as well.

Thanks again guys!

ps: I'm off on a family vacation for a week, so will report back after we get back and I get a chance to throw the S4 batt in there.

F451

Put the S4 batt in the '85, it started right up, running fine. As a matter of fact, it fired up much quicker then it ever has. Fired up fine after repeated attempts.

Took the '85 batt and got it load tested, sure enough, its croaked.

Left the S4 batt in the '85, put the new on in the S4 (my daily driver).

Problem solved!

Thanks for all the help guys!

Ed

Charley B

See post seven. Guess how I knew. :>(

dr bob

One of the minor duties during the annual battery and electrical maintenence ritual (see Wally's great instruction on this...) is testing the fluid in the battery. The testers are cheap, less than $10 for a super-whamadyne calibrated device from NAPA, to a $1 floating colored ***** model from Wal-Mart. The specific gravity of the fluid indicates how well the battery is taking a charge, and how much unreacted acid is available to generate those cranking amps. (VERY simplified description...) You can see when the battery is getting tired, and replace it befoe it strands you. Some folks like to really stretch their luck by running a battery until it just won't start the car any more. I conside rthe direct cost of being stranded, plus all the collateral damage that happens when the alternator has to work extra-hard trying to maintain charge levels in a battery that's already in it's final death throws. The voltage spikes and high numbers observed are known to cause death in LH brains, for instance. IMHO, replacing the battery at the early sign indicated by the fluid tester is the easiest and most convenient way to keep the car available. It's also the cheapest.

F451

Great tips, thanks Bob.

And yes Charley, you were right: replace battery.

Alan

So Ed - did you ever figure out if your multimeter was still lying to you?

It could also be in its battery death-throws and you may need a new one (battery for it OR even a new DMM).

Its always good to know its working before you may need it for real again...

Its never fun having to debug the debug tools when you really just need them to work!

Alan