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

josiah

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Jan 5, 2007
Messages
151
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Make
toyota
Model
camry
Year
1987
Miles
235,000
Engine
4 cylinder
Recent problems and fixes
1) 2020. Problem: Brake lights ON ALL THE TIME.
Fix: Replaced brake light switch cushion with help from Mobile Dan and others. Brake lights fixed.

2) 2021. Problem: Brake lights NOT coming on.
Fix: Determined to be Light Fail Sensor malfunction with help from Mobile Dan and Nickb and others. Jumped sensor. Brake lights fixed.

Current problem
Battery power is dropping below level to crank engine.

Tests I have done
1) Each time after the battery level has dropped I have used battery charger to return it to full charge.
2) When I reinstall recharged battery in car it has started the car easily.
3) Please note: If I disconnect the negative battery cable for days or weeks the battery does not lose power. And it has consistently started the car easily, obviously after I have reconnect the negative cable.
4) Some days I have left both cables connected and started car at appx 4 hour intervals with no problem.
5) However, one day with battery connected, I tried to see if it would crank after 7+ hours and it did NOT. So around 7 hours or more is he breaking point.
6) I did battery test I found online in which you check the battery voltage (A) before crank (B) during crank and (C) after start. In the test you want to see if there is a significant drop in voltage during crank. My reading were 12.8, 10.5 and 15 respectively. So the battery passed the test.
7) With battery connected I have walked around car, and sat in car, after dark to see or hear if any component could be on and draining the battery. I have found nothing.

My further thoughts
1) I think the battery is fine. It passed the voltage test. And when I disconnect the negative cable it holds it's power. Please let me know if my logic is flawed.
You may wonder why I have not taken battery to local parts store for a free battery test, the reason is lack of confidence. I previously lost a good battery trusting in a store's free test.
2) I don't recall having this problem until after jumping the Light Failed Sensor but it may be just a coincidence. But I do not understand how that could drain the battery.

Any advice would be appreciated.

Thanks Joe.
 

grcauto

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Load test the battery.
 

billr

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What DC amperage ranges do you have on your electrical meter? You need to check what the current drain is when the car is supposed to be inactive. There are many things that still could be "on" that you can't hear or see visually.
 

josiah

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billr, Thanks for the reply. My Sears Craftman digital multi meter lists the following DC range settings->A DC->(2m, 20m, 200m and 10). However (1)when I rotate the selector dial it stops and will not allow me to select in the A DC range (also A AC is also blocked) and (2) the meter lists 10A and MA jacks, but the jacks (or ports) are covered preventing insertion of the the test probes (red and black).
The only ranges I can use appear to be CAP, OHM, V DC, V AC and a sound symbol ( which I think is continuity).

grc, Thanks. Please see my original post above, under "Test I have done", #6. Is that an adequate battery test? If not, then how I do a Load Test?

By the way the battery has been sitting in my garage after I fully recharged it. Based on my previous tests it should start the car easy.

Thanks for your help, Joe
 

grcauto

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That test is not adequate. A load test will usually draw about 250 amps and see if it holds at 10.5 or above.
 

billr

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My understanding is that the battery will hold a charge fine if disconnected from the car and will crank it fine when re-connected. OP, is that correct? If so, the battery is probably fine. The problem is more likely to be a (greater than normal) parasitic drain in the car's electrical system.

Finding such a drain without a clamp-on ammeter can be done, but is quite a bit more tedious. You will need to step up toward the $100 range to get a clamp-on that will give enough resolution in the lower amperage range. You need to be able to see drains in the .1-1ADC range.

A simple load test is to leave the headlamps on for 1/2 hour or so, with engine not running. After that 1/2 hr the battery voltage should not drop from 12.6V to much lower than 12V, and should recover to nearly 12.6V once the lights have been turned off again for another 1/2 hr.
 

grcauto

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The only time these battery tests are accurate is when the test fails.
 

josiah

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billr , we agree; that is what happened in my earlier tests.

billr and grcauto,
However now something NEW is happening->
(1) previously on 6/7 I fully charged battery and left it in my garage. On 6/23 I installed it in car, confident that it would crank and start engine based on my earlier tests, but it DID NOT crank. All I heard was one click of the starter.
(2) So 6/23-6/25 I tried 2 more times. Each time I put battery on charger until I got FULL CHARGE light on charger. Installed battery. But each time got no crank.
(3) Also, when I tried to turn on head/tail lights I got no lights, but instead a buzz sound coming from instrument panel around steering wheel area. But a few seconds later when the buzzing stopped the head/tail lights came on.
(4) Also, when I tried to turn on head/tail lights if I mildly nudged the positive battery connector the buzzing stopped and the head/tail lights came on.
(5) Also, when I got the head/tail lights to come on, then I tried to crank engine, as a result the head/tail lights went out.
(6) Also the battery post and connectors appear to be clean enough; so corrosion should not be a problem.
(7) Also, the battery appx 4+ years old.
(8) Also, when turn ignition key the interior door lights (small red lights near bottom of door on driver and passenger side)dim; when I release key they return to bright.
Please let me know if this sends this discussion in another direction.
Thanks, Joe
 

billr

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Well, yes, now that the symptoms have changed, so should we be testing for a different probable problem. It now sounds like there is a problem with connections to the battery; with a hint that it is the positive cable. However, if this is a top-post battery, then try twisting the posts when cable are off. Those posts should have no looseness in the battery. (Side terminals? I have never seen those come loose, but check anyway!)

You need to keep a voltmeter in the car, handy at all times that something doesn't work right (no crank, no headlamps, clicking, buzzing, etc). Find out just where the system voltage is dropping, while the problem is happening.

For example: No crank? Read voltage from battery negative terminal to engine block. Read voltage from battery positive terminal to engine. Read voltage at battery end of the big positive cable. Do same at end of that cable that connects to the starter. If there is a big power contactor connecting the battery to starter, read at both sides of that contactor. You have to make these readings while trying to crank the engine and it won't
crank.

Note the distinction between a battery terminal (post) and the battery cable end. One of the first things we need to check is simply the cable connections to the battery
 

grcauto

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Either that battery is bad or you need to clean and tighten the cables or both.
 

josiah

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I plan to do tests as soon as l find an assistant and time allows.
Thanks Bills, Grcauto and JackC.
 

josiah

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billr,
Please read my replies below in RED.

Well, yes, now that the symptoms have changed, so should we be testing for a different probable problem. It now sounds like there is a problem with connections to the battery; with a hint that it is the positive cable. However, if this is a top-post battery, then try twisting the posts when cable are off. Those posts should have no looseness in the battery. (Side terminals? I have never seen those come loose, but check anyway!) This is a top posts battery and posts are tight.

You need to keep a voltmeter in the car, handy at all times that something doesn't work right (no crank, no headlamps, clicking, buzzing, etc). Find out just where the system voltage is dropping, while the problem is happening.

For example: No crank? Read voltage from battery negative terminal to engine block. Voltage = 0.Read voltage from battery positive terminal to engine. Before turning key voltage fluctuated around 10.8. After turning key it drops to around 2. Read voltage at battery end of the big positive cable. Not certain that I did this test the way you told me. I went from positive battery connector (or cable) to engine block and got reading of 10.5. Do same at end of that cable that connects to the starter. Not certain I did this as instructed. I connected from starter to battery negative. Before turning key reading around 10.5. After turning key voltage dropped to 2 and lower. If there is a big power contactor connecting the battery to starter, read at both sides of that contactor. Missed this test; I plan to take another look. You have to make these readings while trying to crank the engine and it won't
crank.

6/29 When I did the voltage tests I did the following:
1) I used two 4 foot wire extensions, with small alligator clips on ends, connected to my multi-meter (meter was inside car with me). That is how I was able to make connections under hood, turn ignition key inside car and record voltage readings. But I did have to walk back-and-forth to move clips to contact a different part under the hood.
2) For tests instructing me to contact the engine block. I clamped extensions just below the valve cover. I hope that was adequate.
3) If I skipped a test please let me know. But I think I might have missed one test above->" big power contactor connecting the battery to starter, read at both sides of that contactor". I will try to get to that one ASAP.

grc auto and JackC
Yesterday while shopping I made a preliminary stop at Walmart, but the battery was not in stock. If the problem is indeed the battery I plan to buy a new one at Walmart or used one from local PicknPull.

Any advice, questions or comments please let me know. Thanks Joe
 

billr

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Confirm that you had a load on the battery, were trying to crank the engine, when you read 0V from the battery negative terminal to the engine block.

Why is the battery no-load voltage only 10.8V? Are you not charging it, or is that all it will charge to? If that is the highest it will charge to, then it is surely bad. All the testing I described assumed the battery was fully-charged to 12.6V or more.
 

josiah

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billr, please see replies in red below.

Confirm that you had a load on the battery, were trying to crank the engine, when you read 0V from the battery negative terminal to the engine block.
Reply->As I remember on 6/29. (1) I connected one wire extension to battery negative side, with opposite end to the multi-meter COM port ; (2) used other extension from the multi-meter VOLT port to engine block (below valve cover). Then turned the ignition key. I put no additional load on battery; I thought turning the key in order to crank engine was enough. To put load on battery should I turn on lights, radio....?.

Why is the battery no-load voltage only 10.8V? Are you not charging it, or is that all it will charge to? Reply-> No I did not recharge battery. If that is the highest it will charge to, then it is surely bad. No the battery had previously been recharging to 12 or 13. And the FULL CHARGE charger indicator light had shown. All the testing I described assumed the battery was fully-charged to 12.6V or more. No, I misunderstood, I plan to redo tests but recharge battery first. Plan to do ASAP.

Thanks, Joe.
 
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