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

 

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.....

 

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.

 

Batery is brand new so I'll check earths

cheers

 

I'll recheck everything with a multimeter.

How do I measure current drain? Just measuring ampage across battery terminals?

 

Use a multi-meter set to amps, disconnect the -neg lead from the battery, put one probe on the -neg terminal of the battery and the other probe to the -neg lead that went to the battery. You should get a reading of what is being drawn.

 

b13bat - thanks for that. I really should know that after doing elec engineering at college for 2 years

Will check and report back !

Would this drain be causing the CEL?

 

Very doubtful that a couple of watt bulb would cause many problems. See what the drain is, if it is sweet fa then it's probably an earth issue.

 

You cant check earth quality with a multimeter, unless it cost a lot of money.

 

As above, but don't use a multimeter to measure current draw with any large load, like the starter, being used.

 

so what should I use to measure current draw?

thanks

 

clamp on Ammeter is the easiest to spot any big current draws

 

A multi-meter will be fine for checking 'direct' battery drain.

As GC8 says, not for large cranking Amps. But as you are just checking the system for leaks with the engine off and not the cranking Amps you should be fine with a DMM.

 

As above.
Use it to check if there is a current draw with everything apparently switched off.

NOT to check the current draw of the starter!

 

Ok - managed to find a multimeter and the results are as follows:

Ignition off: 13.3v across battery

Ignition on: 14.4v across battery

Ignition off: 0.15A drain after putting meter in series

Any thoughts?

 

Yes: that sort of constant drain will soon lower the available charge in a VERY cold battery. You need to find out what it is and disconnect it if possible.

 

cheers Alcazar - what do you recommend? Disconnecting all fuses and then plugging back in one by one?

Do you think this will also be the cause of the CEL Low alternator circuit voltage issue?

thanks bud

 

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.

 

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

 

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.

 

So one week is 50% which as I said, it should stand for longer than a week and still be able to start. A 50% charged battery in healthy condition will start an engine (as demonstrated in the other alternator thread ), so it not lasting even a single night but with only 0.15amp drain simply doesn't stack up - it should last a lot longer than that even with that drain present - even in this weather.

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).

 

Big fat wire on the alternator with the red cap is positive, negative is anywhere thats shiny metal on the engine itself.

 

Not saying it's JUST the battery, Ali.

What if the OP has thicker oil in? What if the battery isn't in tip-top condition? It IS pretty cold, y'know........

 

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.

 

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.