Battery power (voltage) level drops below level to crank engine

[josiah]

billr, grcauto, jackc, mobile Dan

Brief summary to date
1) posts 1 Thru 7->original problem. Battery voltage drops below level to crank engine. Here is how it happened. I would start with a fully charged battery, install in car, crank and start . Wait appx 3 hours, try again, I still got crank and start. However, wait around 8 hours or more, try again, but now no crank.
Now, if I disconnected the negative battery cable while car was not in use, all I had to do was reconnect cable, crank and start. It didn’t matter if it was days or weeks later.

2) posts 8 thru 21->problem change. Installed fully charged battery, and to my surprise got no crank. Recharged battery but still no crank.

3) posts 22 thru 30-> I tried my battery charger start engine function. Still no crank. But now a new problem, there is no voltage coming from the battery. No interior or exterior lights.

wednesday 7/27
1) the positive cable has a box with MAIN 40A/ALT 80A/ AM2 30A. Are these fuse links? The reason I asks is because my manual mentioned fuses and links.
2) I removed the 40A and 30A. Did continuity tests, and they passed. The 80A was tight so I did not test it.
3) battery voltage=14.95. Last charged 7/6 or three weeks ago. It has been in box in garage mostly.
4) i cleaned battery posts (terminals) and positive cable connector(for third time). installed battery. all lights now work. ENGINE CRANKED and STARTED. and it started quickly, I bearly heard the starter

yes the good news is it cranked and started.
but the bad news is I don’t know what prevented it from cranking in the first place.

Your advice is appreciated.

thanks, joe

 

[billr]

When you checked the fuses and re-connected the battery things got moved; maybe just slightly, but still moved. A poor connection, likely in that main cable, got disturbed and "healed". It could stay OK now for years, or could go open-circuit the next time you jostle the car.

When you have a hard failure, the no-crank or no-lights, you have to start probing with the voltmeter right then to narrow down where the problem may be. Don't wiggle or disconnect anything until you are done tracking with the voltmeter.

 

[billr]

I just browsed through the thread again. As I understand it, when you had a "no lights" situation you found 12V (or better) at the battery positive terminal, but only 4-5V down where that main cable connect to the starter. That pretty much proves there is a problem with the cable, either wire or crimped-on terminals, or a problem with how well the cable terminals are attached to the battery/starter. Was there ever any corrosion at that battery terminal? Acid can wick down into the cable strands and eat them away, but the damage not be visible under the cable insulation jacket.

 

[josiah]

Billr question (above)->......corrosion at the battery terminal?
my reply=>there was moderate corrosion; not significant. Based on my limited experience.
i plan to do more voltage testing, including re-doing the voltage test at starter nut and positive terminal. i will try not to bother any wiring.

thanks, joe

 

[billr]

Does it crank OK now? If so, there is no point to testing voltages. The problem is gone for now, you have to wait until it pops-up again to use the meter.

If there was ever any corrosion at the battery terminals, there is a chance acid wicked into the cable and damaged it. You have a new battery now, correct? So we can probably ignore the chance of a battery terminal loose in the battery.

This sounds so much like a bad cable, I suggest removing the cables for thorough inspection.; usually those big cables are not too hard to remove. With a cable out in bright light. flex it in various places and pull on it applying tension. You are looking for any signs of "softness" or sharp bending. as well as any bumps in the insulation indicating corrosion underneath. Especially pay attention to the ends of cables that connect to the battery.

 

[josiah]

Billr,
8/3/22
1)today checked battery voltage=14+(note: negative battery cable left disconnected since 7/27).
2) turned on head and tail lights
3) redid tests With lights ON.
Battery negative to ground=0 or .o2
battery negative to positive cable=14+
battery negative to starter nut=14+
4) NOW THE moment of truth. turned the key and engine DID NOT CRANK.
As before got a click on the first try, but on the next tries nothing.
funny but the previous time I tried to start it on 7/27 , it started immediately. And I did not disturb the wiring during my testing.
5) noticed later NO LIGHTS (head or tail )in addition to no crank.
6) I have not bought a new battery. Same battery.
7) removing the battery cables sounds like a very difficult job. Are there some tests I can do to confirm that the problem is in the cables?
thanks, joe

 

[grcauto]

You battery is over 14 volts and it's not hooked up or engine running?
Is your meter OK? Don't you find it strange that your 12 volt battery has more than 14 volts?

 

[josiah]

billr, grcauto, jackC,

grcauto, yes, with the car inactive, I am getting a battery voltage reading of over 14.
The multi-tester has a warning light indicating when the tester's battery is getting low, and that light has been ON. ASAP i can change the tester battery to see if that makes a difference. I think it's worth a try.
Also, recently I have used the tester to test small household batteries and it measured voltage reasonably well.
Also, I noticed it's ALL OR NOTHING, what i mean is it cranks and starts "strong", or it doesn't crank at all.

Thanks, Joe

 

[josiah]

billr, grcauto, jackC,

grc, I installed a new battery in my multi-tester. Once again tested my car battery voltage and got a reading of 12.24, instead of 14+.
Out of curiosity I put the old battery back into the tester and again i got readings of 14 thru 15+ volts.
I didn't know that a low battery in a tester could cause false readings, especially high false readings.
Thanks for catching that grc!!!

billr, grcauto, jackC, If there are any tests that I need to redo, or any additional tests, please let me know.



Thanks, Joe

 

[billr]

That 14V is a bit unusual, but not impossible. In fact, 13.6V is pretty common for a battery that has been freshly charged, before any load has been applied. Just a bit of load/discharge brings the charge right back to the theoretical 12.6V. Note that 12.6V is "nominal" at a specific temperature; not an absolute value for all (lead-acid) battery conditions.

Testing at the big nut on the starter usually doesn't tell anything about that big cable, which I suspect is the problem. You need to test for voltage at the starter at three places, but while trying to crank the engine and with "no crank" results. Check voltage at the big cable nut, and then at the other big nut that holds the very short cable/strap that goes into the starter motor, and then at the small wire connected to the starter solenoid. All three of those should be 11V, or better, while trying to crank.

 

[josiah]

Billr,
thanks for additional tests.
All three tests done (1) with battery fully charged to 12.51 volts, I have a Haynes repair manual which said that battery should be fully charged before doing tests (2) while trying to crank engine (3) with black test probe connected to battery negative side (4) used extensions connected to my multi-tester.
voltage results:
1. Big cable nut. Here I am confused because I see only two nuts. One on the starter solenoid; and the other near the positive battery terminal. The nut by battery reading=12.36.
2. nut which holds strap between starter motor and starter solenoid=.01 thru .03. This nut did have rust which I tried to file some of it off.
3. small wire connector located on side of starter solenoid. I pulled the connector out and inserted part of a paper clip inside and took reading=11.66.
please let me know if any readings are questionable; I will gladly re-do.

thanks, joe

 

[billr]

That big nut on the strap should have the same voltage as the other big nut (12.36V) when trying to crank. The solenoid is bad, the main contacts are not "making". The 11.66V on the small wire indicates the solenoid is getting powered on properly, and you hear one big "click" when the key is turned to crank, correct?

 

[josiah]

billr,
1) please see your instructions in reply #40 above, where you instructed me to test at the BIG CABLE NUT. On the positive battery side I tested at the nut which connects the positive cable to the positive battery clamp. Question, did I test at the correct nut?
2) usually the first time you turn the ignition key there is a noticeable click. And tries after that you get nothing.
3) now the STRAP NUT (between the starter motor and solenoid) does have rust on it. Could the rust cause a almost zero voltage reading?

Please let me know if there are any additional tests?

Odd but the previous repair I did, with the help of Batauto, was the brake lights were not working. To fix it I jumped the Light Failed Sensor as instructed and lights now work. I assume it is just a coincidence that the current electrical related problem would occur?

Also, the last times it did crank, which has been quite a while ago, it would crank and start so fast it scared me!!!!

Thanks, Joe

 

[billr]

billr,
1) please see your instructions in reply #40 above, where you instructed me to test at the BIG CABLE NUT. On the positive battery side I tested at the nut which connects the positive cable to the positive battery clamp. Question, did I test at the correct nut? The big nut on the cable should have battery voltage (approx. 12V) at all times. The other big nut, holding the strap, should have virtually the same voltage when trying to crank. Inside the solenoid is a hefty switch that connects those to nuts together when trying to crank and the solenoid is energized.
2) usually the first time you turn the ignition key there is a noticeable click. And tries after that you get nothing. That sounds odd. The solenoid should "click" every time you turn the key to energize it, trying to crank.
3) now the STRAP NUT (between the starter motor and solenoid) does have rust on it. Could the rust cause a almost zero voltage reading? Rust on the nut usually doesn't matter. How about the stud the nut is on, isn't that copper? When making readings at either nut, try to stab the meter probe into the end of the stud

Please let me know if there are any additional tests? My understanding is that when trying to crank you have 12V at the big cable, 12V on the small wire, and 0V at the strap. That pretty much proves the solenoid is not operating correctly. The only thing further to check make sure you are getting good contact at the strap; that the 0V is a true reading. All these readings should be relative to ground.

Odd but the previous repair I did, with the help of Batauto, was the brake lights were not working. To fix it I jumped the Light Failed Sensor. I assume it is just a coincidence that the current electrical related problem would happen? Right now, I would say coincidence...

Thanks, Joe