Low Alternator Voltage
#1
Low Alternator Voltage
Hi,
not sure if it's related but on a Bugeye MY01 - CEL is on with low alternator voltage code.
Alternator has been replaced - no joy. Battery gives correct readings both on no ignition (approx 13.2v) and on ignition to indicate the battery being charged by alternator.
What could it be?
Now the car refuses to start since it's been frosty and requires a jump if left standing overnight!
Any pointers?
Thanks
Jai
not sure if it's related but on a Bugeye MY01 - CEL is on with low alternator voltage code.
Alternator has been replaced - no joy. Battery gives correct readings both on no ignition (approx 13.2v) and on ignition to indicate the battery being charged by alternator.
What could it be?
Now the car refuses to start since it's been frosty and requires a jump if left standing overnight!
Any pointers?
Thanks
Jai
#2
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Dodgy earth somewhere. Check all the earths, but if your battery is in any way weak, this weather will not help. Even though the bat shows 13.2v, it could still be fcuked when it comes to cold cranking.....
#3
Scooby Regular
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A battery being charged should be 14.2V to 14.6V especially from cold. Do you have this voltage once the car has started?
Could be faulty new Alternator!
There could be a fault on the car which is draining current when not running. You need a amp meter( any decent multimeter has this function) to measure current leakage. There should be only a few milli amps drain.
Could be faulty new Alternator!
There could be a fault on the car which is draining current when not running. You need a amp meter( any decent multimeter has this function) to measure current leakage. There should be only a few milli amps drain.
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#18
Moderator
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0.15amp drain should give about 333 hours of juice from a good fully charged battery, which is about 2 weeks. So the car should easily stand for longer than a week and be able to start. This drain looks typical of a car fitted with an older variety of tracker IMHO, but before I get ahead of myself, there are some issues I need to question with your readings:
So please clarify:
"ignition on=14.4 volts" you mean with the engine running right?
"Ignition off" Confirm everything is off, no key in the ignition, doors closed and left for 30seconds etc. (interior light, and don't foget the little light on the dash that says the door is open, that draws a bit of current too ). If you left the door open or keys in the ignition, do it again and recheck current drain.
Finally 13.3volts with ignition "off" is obviously a incorrect reading. As this indicates there is still surface charge on the battery from earlier running of the engine or charging it within a few hours of testing. To get a "true" open circuit battery voltage you really should leave it for a few hours minimum to allow surface charge to dissipate and settle. Disconnecting the battery overnight and then testing the voltage the next morning is ideal (with it still disconnected).
Also take measurements across alternator positive and engine block with the engine running and with headlamps turned on. and compare to the voltage across the battery terminal; a significant difference between the two readings indicates a wiring issue.
Further more advanced testing would be back probing the ecu earths and supply terminals; as if you are getting a voltage CEL this is where the ECU would take its measurements from. Pin outs and diagrams are in the archive section. But personally BEFORE going that far, I think the CEL cerror ode is a red herring, its probably been logging that code when trying to start the car with a flat battery. So it needs to be cleared and checked to see if it returns and it'll probably be logged again the next time the car refuses to start and need to be jump started...which to me points to a flat/duff battery, results of the battery voltage reading after being disconnected overnight should help confirm this.
So please clarify:
"ignition on=14.4 volts" you mean with the engine running right?
"Ignition off" Confirm everything is off, no key in the ignition, doors closed and left for 30seconds etc. (interior light, and don't foget the little light on the dash that says the door is open, that draws a bit of current too ). If you left the door open or keys in the ignition, do it again and recheck current drain.
Finally 13.3volts with ignition "off" is obviously a incorrect reading. As this indicates there is still surface charge on the battery from earlier running of the engine or charging it within a few hours of testing. To get a "true" open circuit battery voltage you really should leave it for a few hours minimum to allow surface charge to dissipate and settle. Disconnecting the battery overnight and then testing the voltage the next morning is ideal (with it still disconnected).
Also take measurements across alternator positive and engine block with the engine running and with headlamps turned on. and compare to the voltage across the battery terminal; a significant difference between the two readings indicates a wiring issue.
Further more advanced testing would be back probing the ecu earths and supply terminals; as if you are getting a voltage CEL this is where the ECU would take its measurements from. Pin outs and diagrams are in the archive section. But personally BEFORE going that far, I think the CEL cerror ode is a red herring, its probably been logging that code when trying to start the car with a flat battery. So it needs to be cleared and checked to see if it returns and it'll probably be logged again the next time the car refuses to start and need to be jump started...which to me points to a flat/duff battery, results of the battery voltage reading after being disconnected overnight should help confirm this.
Last edited by ALi-B; 22 December 2010 at 12:34 PM.
#19
Hi Ali-B,
thanks for taking the time out to write all that
There have been some weird electrical issues with the alarm in the past with some random wiring etc - now that you mention tracker - maybe this was what it's down to??
14.4v is with ignition on and engine running
Igninition off is with nothing running inside the car - I've left the multimeter stabilise and kept it there for a minute before taking the readings.
I should point out that this is a new battery (from the one when I originally posted above - but still showing the same issues. The original battery decided to give up the ghost when the weather took a nasty turn despite me trying to get the alternator to give it a charge.... it might still work but the battery didn't let the engine turn over. The new one has been ok thus far.
How do I check voltages across alternator block? Just touch the casing and obviously ensure I'm earthed?
I'll have to do the rest on the weekend as I won't have time tomorrow. Will report back
thanks for taking the time out to write all that
There have been some weird electrical issues with the alarm in the past with some random wiring etc - now that you mention tracker - maybe this was what it's down to??
14.4v is with ignition on and engine running
Igninition off is with nothing running inside the car - I've left the multimeter stabilise and kept it there for a minute before taking the readings.
I should point out that this is a new battery (from the one when I originally posted above - but still showing the same issues. The original battery decided to give up the ghost when the weather took a nasty turn despite me trying to get the alternator to give it a charge.... it might still work but the battery didn't let the engine turn over. The new one has been ok thus far.
How do I check voltages across alternator block? Just touch the casing and obviously ensure I'm earthed?
I'll have to do the rest on the weekend as I won't have time tomorrow. Will report back
#20
Scooby Regular
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Ali: your 333 hours is a bit misleading. That would TOTALLY flatten a fully charged 50Ah battery. That's not what we are talking about.
TBH, he wouldn't need to have much charge removed before, IN THIS WEATHER, the battery would have insufficient charge to both spin a stone cold engine AND generate sparks.
TBH, he wouldn't need to have much charge removed before, IN THIS WEATHER, the battery would have insufficient charge to both spin a stone cold engine AND generate sparks.
#21
Moderator
iTrader: (1)
Ali: your 333 hours is a bit misleading. That would TOTALLY flatten a fully charged 50Ah battery. That's not what we are talking about.
TBH, he wouldn't need to have much charge removed before, IN THIS WEATHER, the battery would have insufficient charge to both spin a stone cold engine AND generate sparks.
TBH, he wouldn't need to have much charge removed before, IN THIS WEATHER, the battery would have insufficient charge to both spin a stone cold engine AND generate sparks.
What I'm simply saying is that current draw isn't the sole issue here (unless the car has stood previously and the battery has not been subsequentally fully/properly charged or the car has been used on frequent short journeys).
Last edited by ALi-B; 22 December 2010 at 04:04 PM.
#24
Moderator
iTrader: (1)
Oil shouldn't be an issue here unless its running on two year old sludge from the bottom of a waste oil barrel; We're talking about a lightweight 8.0:1 compression engine here, so it doesn't take much juice to spin over compared to, say, the average normally aspirated engine- despite the cold.
You are right though, the battery maybe discharged and crying out for an overnight charge. People don't realise that the engine will not fully charge a flat battery, unless one goes for a 12 hour drive.
You are right though, the battery maybe discharged and crying out for an overnight charge. People don't realise that the engine will not fully charge a flat battery, unless one goes for a 12 hour drive.
Last edited by ALi-B; 22 December 2010 at 09:08 PM.
#25
Not sure on your car, but some vehicles (my Berlingo van for instance) have a sense wire running from the alternator to the ecu so the ecu can monitor alternator output voltage. If this wire is removed/broken an alternator error is generated even though the alternator is working fine.
If you have one it will be a small wire which may be connected to the alternator in a different location to the heavy gauge battery cable.
If you have one it will be a small wire which may be connected to the alternator in a different location to the heavy gauge battery cable.
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