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Battery or Alternator at fault?
stevebubs - 3/6/06 at 03:07 PM

When the engine is cold, my battery seems to have enough juice to turn the car over and start it without issue.

When hot, it doesn't but jumpstarting from another car works first time so overheated starter (first suspect) not at fault.

When the engine is running, however, I don't seem to ever get more thank 13.7 volts across the terminals. However, my multimeter is a bit flaky in the voltage area.

Q: Which is more likely to be the culprit? Alternator or Battery (Battery has been deep discharged a few times, so could be problematic)??

Stephen


britishtrident - 3/6/06 at 03:14 PM

What ignition system ? it sounds like it gives too much static advanced to me.

13.7 should be more than enough volts.

[Edited on 3/6/06 by britishtrident]


stevec - 3/6/06 at 03:56 PM

13.7 Jolts is perfect.


stevebubs - 3/6/06 at 04:47 PM

quote:
Originally posted by britishtrident
What ignition system ? it sounds like it gives too much static advanced to me.

13.7 should be more than enough volts.

[Edited on 3/6/06 by britishtrident]


Nope - checked all that. Static advance has been played with - was 10 degrees but backed it off to 8. No change. Don't think jumping it would help if it were the advance anyhow.

Looks like a new battery then....

Stephen

[Edited on 3/6/06 by stevebubs]


britishtrident - 3/6/06 at 08:26 PM

Its not the battery to confirm just do a cranking voltage test,


stevebubs - 3/6/06 at 08:31 PM

quote:
Originally posted by britishtrident
Its not the battery to confirm just do a cranking voltage test,


OK....bit more info on what to do and results to expect, please...?

[Edited on 3/6/06 by stevebubs]


britishtrident - 4/6/06 at 10:50 AM

Really just the voltage when cranking the engine but with no spark.

Should be about 10+ volts on a fully charged battery .

A voltage bellow 9 volts especially in a a cold start scenario indicates a dead or gassing cell.
Normally a battery with a dead cell shows about 6 volts under heavy load but may rise to 8 volts after a few seconds.


02GF74 - 6/6/06 at 02:26 PM

quote:
Originally posted by stevebubs
When the engine is cold, my battery seems to have enough juice to turn the car over and start it without issue.

When hot, it doesn't but jumpstarting from another car works first time so overheated starter (first suspect) not at fault.




right, to start an engine it needs to be turned over and a spark supplied at the right moment to ignite the mixture.

you say this happens ok when cold but do not give the same info. when hot. Does the engine turn over when hot? if it does, the battery is fine and you need to investigate the ignition and maybe fuelling - the latter probably is not the problem since the engine starts when more oompf is added.

Bear in mind electrical compenents have different characterisitcis when hot thant when cold - coil could be breaking down, condenser etc: plus an y leads are higher restistance.

Also when hot, metal and other stuff expands and it may be that somethig is no longer making proper contact.

What happens if you start up from cold, stop the engine then try to restart? And repeat, maybe at 2 minute intervals to see when it fails to start.

you checked the ignition fuel side to be ok?

alternator voltage at 13.5 V is fine.