Random loss of all electrical power
#16
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There aren't any - in any case with those its a one way trip...
Bill from what you describe its isolated to the battery itself (internal issue) or more likely (since I assume you jiggled the cables but didn't really jiggle or remove the battery itself) the positive supply to the ~Starter.
Have you tried a new/alternate battery - I'd swap one in first - easy to test.
It clearly isn't an alternator issue - since you say it stays running well once running and so the wiring from the Alternator to the Jump Post and Jump Post to CE sounds fine. So most likely remaining is the Battery to Starter cable. It could also be the cable from the Starter to Alternator/Jump post.
You can try to test for voltage as Jim notes - do this with ignition on - but this does require the car cooperates and fails while you are ready to test...
You could also strip back the sheathing from the ends (start battery end on Bat/Starter cable) and see if its heavily corroded (my guess is right there if you get this far).. If its not these then you can use HD heat shrink tube to repair the ends.
Alan
Bill from what you describe its isolated to the battery itself (internal issue) or more likely (since I assume you jiggled the cables but didn't really jiggle or remove the battery itself) the positive supply to the ~Starter.
Have you tried a new/alternate battery - I'd swap one in first - easy to test.
It clearly isn't an alternator issue - since you say it stays running well once running and so the wiring from the Alternator to the Jump Post and Jump Post to CE sounds fine. So most likely remaining is the Battery to Starter cable. It could also be the cable from the Starter to Alternator/Jump post.
You can try to test for voltage as Jim notes - do this with ignition on - but this does require the car cooperates and fails while you are ready to test...
You could also strip back the sheathing from the ends (start battery end on Bat/Starter cable) and see if its heavily corroded (my guess is right there if you get this far).. If its not these then you can use HD heat shrink tube to repair the ends.
Alan
Last edited by Alan; 01-02-2013 at 12:42 PM.
#17
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Lots of times people wiggle, jiggle,pry, pull off or pound on battery terminals and end up damaging the post internal connections. The fact that the battery has been touched several times increases the possibility..
#19
Bill, do you know how old the ignition switch is?
#20
Just repeating what has already been written: test with voltmeter progressively if the car has obligingly failed at your convenience (between battery posts, positive battery post and ground, far end of positive cable and ground, etc.) until you find the open circuit, or if the problem does not cooperate, replace the battery to see if problem does not return in the future.
FWIW, the battery in my boat caused a fairly similar problem: all seemed well and everything worked as it was supposed to (fans, lights, other low power items) until the starter was engaged and then all power disappeared; fiddling with the battery cables brought power back until the starter was engaged again, which immediately caused the battery voltage to drop to zero. A kick to the battery brought voltage to normal as did turning it on its side or upside down (it was a gel cell, not a flooded battery). Many repetitions produced the same result each time. OTOH, this battery never again was able to start the motor, unlike the problem you describe.
Good luck.
Bob
FWIW, the battery in my boat caused a fairly similar problem: all seemed well and everything worked as it was supposed to (fans, lights, other low power items) until the starter was engaged and then all power disappeared; fiddling with the battery cables brought power back until the starter was engaged again, which immediately caused the battery voltage to drop to zero. A kick to the battery brought voltage to normal as did turning it on its side or upside down (it was a gel cell, not a flooded battery). Many repetitions produced the same result each time. OTOH, this battery never again was able to start the motor, unlike the problem you describe.
Good luck.
Bob
#21
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I had a battery act up with internal shorting in another car a while back. I'd do the voltmeter test at the terminals and work forward while it's acting up, or just replace the battery with a known good one for a while.......
#22
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Lots of talk about internal battery shorts - thats not really very likely here.
An internal battery plate short will rapidly cause that cell to discharge - possibly overheating and damaging (even exploding) the battery. Its not usually recoverable, battery becomes pretty useless (voltage drop, usually also accompanied by higher internal resistance due to secondary effects).
A battery open circuit is more plausible here especially related to terminal physical damage. In this case messing with the terminal itself, or battery movement or heat or current loading can all cause changes in the behaviour. Heat being the most likely explanation of purely temporal changes.
e.g. let it sit and it fixes itself...
Alan
An internal battery plate short will rapidly cause that cell to discharge - possibly overheating and damaging (even exploding) the battery. Its not usually recoverable, battery becomes pretty useless (voltage drop, usually also accompanied by higher internal resistance due to secondary effects).
A battery open circuit is more plausible here especially related to terminal physical damage. In this case messing with the terminal itself, or battery movement or heat or current loading can all cause changes in the behaviour. Heat being the most likely explanation of purely temporal changes.
e.g. let it sit and it fixes itself...
Alan
Last edited by Alan; 01-02-2013 at 08:42 PM.
#23
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The battery is getting a lot of press. So far, the battery looks good to me. When the electrical system was dead, I still measured ~12.7V across the posts, even when seeing only 2-4V at the jump post. And then there is the report by the owner of no response at all to a jump with an external battery.
Having dealt with broken posts before, I've tried to wiggle the posts and have seen no change in battery voltage and there is no movement in the posts. AFAIK, they haven't been pounded on. I could not reproduce the problem by manipulating the battery posts.
Doesn't the lack of response to a jump at the jump post implicate the engine harness? It's a little confusing to me. I gather from the wiring diagram that the battery positive cable goes to the starter, then via the engine harness to the alternator and the jump post. If the battery ground is good, for the battery not to provide any power, I would think the section of cable from the battery to the starter would be implicated. For the jump post to not start the car, I would suspect the engine harness. I have to double check that the owner actually tried to jump at the jump post rather than at the battery itself or is there a cause that would account for both failures?
If just the battery is bad, I would still expect a jump with an external battery to do something.
Having dealt with broken posts before, I've tried to wiggle the posts and have seen no change in battery voltage and there is no movement in the posts. AFAIK, they haven't been pounded on. I could not reproduce the problem by manipulating the battery posts.
Doesn't the lack of response to a jump at the jump post implicate the engine harness? It's a little confusing to me. I gather from the wiring diagram that the battery positive cable goes to the starter, then via the engine harness to the alternator and the jump post. If the battery ground is good, for the battery not to provide any power, I would think the section of cable from the battery to the starter would be implicated. For the jump post to not start the car, I would suspect the engine harness. I have to double check that the owner actually tried to jump at the jump post rather than at the battery itself or is there a cause that would account for both failures?
If just the battery is bad, I would still expect a jump with an external battery to do something.
#24
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The chassis to engine block ground is not a culprit - could be for other issues like no starter action - but not for total loss of CE power.
Alan
#25
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As recall the wire to the jump post is not really a heavy enough gauge to flow enough power to start a 928 with no battery.....it is not battery cable. Jumping there is to assist in starting a car with a low battery.
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Alan
#27
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If it runs reliably once started, then you know that all of the wiring from CE panel to jump-post to alternator, to starter, to battery terminal (where the EZK and LH get their separate power) is all good. The alternator is supplying the voltage and it is being properly distributed everywhere.
After replacing that wire it spun over so fast i thought valves were bent.
#28
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... If it runs reliably once started, then you know that all of the wiring from CE panel to jump-post to alternator, to starter, to battery terminal (where the EZK and LH get their separate power) is all good. The alternator is supplying the voltage and it is being properly distributed everywhere.
Now if the battery goes out of the alternator circuit its quite likely that the voltage regulation will be very poor - voltage stabilization, level and ripple noise will all get worse. You may get more radio interference/noise, higher/erratic readings on the voltage guage... any of this ring any bells after running for a while...?
Alan
#29
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Not quite true... Assuming the battery is good the ECU's will be getting power anyway from the battery (while discharging) so it means nothing about the continued goodness of the battery to starter to alternator segments - only that the alternator to CE is good.
Now if the battery goes out of the alternator circuit its quite likely that the voltage regulation will be very poor - voltage stabilization, level and ripple noise will all get worse. You may get more radio interference/noise, higher/erratic readings on the voltage guage... any of this ring any bells after running for a while...?
Alan
Now if the battery goes out of the alternator circuit its quite likely that the voltage regulation will be very poor - voltage stabilization, level and ripple noise will all get worse. You may get more radio interference/noise, higher/erratic readings on the voltage guage... any of this ring any bells after running for a while...?
Alan
Bill did report a higher voltage at the console voltmeter at one point so that fits.