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Discussion Starter #1 (Edited)
Hi,

I have just had the battery charge fault message come up on my 307 2.0 hdi 110.

When using PP2000 before i was getting 14.4v but now am just getting 11.6v or thereabouts with the engine running as the battery is getting a little flat.
Have checked all the connections on the altenator,battery and the main engine and body earths and all seem ok.
Auxiliary belt all seems ok and tensioned.
Havnt yet removed the fusebox and checked underneath for any dampness but from looking at it in situ it looks bone dry from what i can see.

When i checked for voltage at the altenator the thick wire had 11.6v (battery voltage at it) but when i checked the small exciter wire or whatever it is called i am only getting appx 4v ???

According to the wiring diagrams i have this wire comes from a 2 wire plug on the BM34 fusebox and again i have only 4v at this connection.
From there it appears to goto to the BSI but i havnt had time tonight to go tracing it any further

Is this correct?? I have until now always thought an altenator needed 12v or so on this wire for it to start charging or is the 4v reading correct.

Was thinking about connecting a 12v feed to the small wire (with the wire from the car going to the fusebox disconnected) to see if it starts charging but didnt want to try it without some conformation that it should be 12v and not 4v first incase i damage anything further.

One other thing i have been noticing recently when disconnecting or reconnecting the battery there seems to be a fair spark when i take the lead off,(more than what i would have thought normal) but never got round to checking the actual ampage being drawn.
Could this have been maybe a faulty altenator discharging the battery and now its finally given up the ghost??

Still dont understand the 4v reading though.

Regards Terry
 

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The small wire is the excitation for the rotor. It is not necessarily 12V, and you may damage the alternator if you apply that. It is a varying voltage, controlled by the voltage regulator function in the BSI, to maintain the alternator output volts at the design figure (usually about 14.3V), so it's value will depend on the state of the battery and the car's electrical load.

As your alternator is giving low output volts, the problem may be in the BSI, but it could be the alternator brushes, which connect the excitation to the rotor. Or a bad earth.

I would have the alternator checked by an auto electrician.
 

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Discussion Starter #3 (Edited)
Thanks for replying.

Yeh i was concerned applying 12v to the exciter might damage something so will give that one a miss.
I have had the battery on and off a lot recently whilst doing other work to car using the battery removal procedure but will maybe try another BSI reboot just incase something went wrong when i was doing it.

Pretty sure the earths are ok,
I have a spare alternator from an old 307sw hdi 90 which looks the same i guess i will have the knuckle scraping job of changing it tomorrow night and see what happens if rebooting the BSI doesnt work.

Will post results when i get it done

forgot to say when i check the BSI using PP2000 it says no faults found

Terry
 

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Try 12 volts into the exciter circuit on the alternator with the wire disconnected as it does indeed want 12 volts if its a single wire exciter and your alternator may well be fine if after feeding it 12 volts it starts charging then your wiring is suspect somewhere.
if it still does not charge the alternator is faulty
 

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Discussion Starter #6
Just a quick update on my progress or maybe lack of it.

Didnt have time tonight to change the alternator so had a go at checking things again.
Have noticed that where i was getting 4v on the exciter wire whilst it was plugged into the alternator when i unplug it and check at the end of the plug i am getting 12v or thereabouts ie battery voltage but as soon as i plug it back into the alternator and test at the back of the plug its back to appx 4v???

Then decided to try reliables advice and cut the exciter wire and connected a wire from it directly to the battery,started the car up and hey presto im getting over 14v according to PP2000 although i noticed instead of the steady 14.4v i was getting before this problem started when i have the exciter connected from the battery PP2000 shows the voltage wandering between 14.3 to 15.1 and when i turn on the headlights you can clearly see them going brighter and dimmer with the voltage varying.

Is this maybe the regulator being faulty in the alternator,possibly maybe an internal short circuit and when its connected to the wiring in the car if it is regulated by the BSI as ianML suggested maybe the BSI is reducing the voltage to 4v to compensate for the short circuit.

Or possibly the internal short is causing the 12v supply to the exciter to drop to 4v but to me surely something would get hot if that was the case but none of the wires seem to heat up.

Another thing i noticed was in my first post i mentioned when i connected the battery there seemed to be an unusually large spark when connecting the leads even with ignition and everything switched off (at least to me anyway)
but if i unplug the exciter wire,ignition and everything off the spark is very much reduced,which confuses me a bit as with the ignition off the exciter wire isnt powered up but definately reduces the spark when connecting the battery.

Another thing i have noticed is when i charge the battery ,connect it up and start the car according to planet the battery voltage is 12.6v but after only about 5mins or so running its dropping rapidly and the lowest i seen it goto was 9.3v by which time all the ECUs were throwing the dash warning lights on like a christmas tree.
Is this a faulty battery or just the alternator draining it??

Sorry for long post just a bit baffled by all this,my guess now is maybe try a known good battery although the battery on the car is only about 6months old according to the previous owner and see if that drops in voltage so much or try changing the alternator for the spare one i have of my old hdi90..

Any advice gratefully received.

Regards Terry
 

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Maybe the BSI controlling the excitation is not correct. I got that recently from someone else on this board, but if the alternator has a separate regulator mounted on it (which does seem to be the case) it may be wrong. Two regulators in series sounds like a recipe for chaos. It's hard to find reliable information on the topic.

On the other hand, with 12V directly from the battery allowing the alternator to get back up to the right level, it does suggest a fault in the BSI or associated wiring. A high resistance defect could account for the excitation volts dropping to 4V when excitation current is being drawn.

The fluctuation is odd. I'm tempted to suggest two faults - the second in the alternator's voltage regulator.

My guess about the variation in spark size is that it is caused by capacitance inrush current - the charge warning lamp seems to be driven by an emitter-follower circuit in the BSI, but I have no detail on the surrounding components. Although the power to the exciter circuit is controlled by the ignition switch, there seems still to be components in that area in-circuit with the ignition off.
 

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Your alternator output should be stable after energising it so i recon your alternator is faulty but you might have another problem.

Big spark when connecting is common some do it some dont its never worried me but it could be a bad diode in the alternator drawing power although i would not expect a good charge then.

Think your going to have to change the alternator :(
 

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Discussion Starter #9
Hi guys,

Woke up this morning and read ianMLs post about the BSI excitation not being correct and couldnt help but think the worst,

Any way came home from work and got stuck into changing the alternator,wasnt that bad a job,really not as tight for space as i thought anyway.

got the new alternator on and before fitting the belt i checked the exciter wire whilst it was connected up to the alternator and where i was getting 4v last night with the new one fitted i was now getting 12.2v with the ignition on :thumb: :D

Then fitted the belt back on and everything working just as it should 14.5-14.6 volt on tickover with no load and dropping to about 14.3 with headlights,heater blower,rear demister on,and nice and steady too no flickering like last night ..:D

Well delighted,,i guess the old alternator must have a short circuit inside it,will need to get it checked out.

Anyway many thanks for your replys and help ianML and reliable406 always nice to get a second or third opinion when things dont make sense to you.

Cheers Terry
 

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So glad I found this post. "Battery supply fault" has been doing my head in. Alternator voltage 13.7 is not great. Exciter wire 8.7 volts. I'm off to insist factory alternator (less than a year old) is replaced under warranty.
I find Peugeot dealers in Australia have no idea.Thanks.
 
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