C5 2.7hdi charging issue

[Kenmac15]

Evening all
Last week I had the Battery charge or electrical supply faulty warning, after 2 mins went off & all was OK until Thursday as it came back up again but didn't go off & battery went flat so needed recovering home.
Charged the battery over night & it fired up but was only showing an output of 11.6v so cleaned the positive pin under the bonnet, checked the condition of the connections on the battery in the boot & all in really good order.

So today changed the alternator, & 13.8 to 14.1 output left car running for 40 minutes & still showing 13.8v happy day's........ so went on a 10 mile drive 10 minutes in warning came on again so limped it home & only 11.6v going to the battery, exactly the same before.
So any more ideas as to what else it could be before I take a hammer to it

[Jay-Bruce]

Not going to go into baby steps lest I patronise you, as you pretty evidently know your way around a car, and if you've changed the alternator, you're obviously handy enough with a set of spanners. But if the new alternator isn't playing ball, I'd be inclined to look at the exciter wire, which is an ignition live, you could have an intermittent ign-live to the exciter terminal that is leaving the alternator effectively idling rather than charging. Maybe try reterminating the excitor wire with a new crimp terminal and or running a new ign live to the alternator?

[Jay-Bruce]

@givemeabreak - can we get a wiring diagram for the charging system?

[GiveMeABreak]

X7 2.7 Starting Circuit



1020: Alternator
Wires
1087: Alternator excitation command
104: Alternator charge info

010: Starter
100: Solenoid Control

1031: Battery Charge Status Unit

[xantia_v6]

You will note that the alternator is controlled by the engine ECU, so you may need to have the fault codes read to see what is going on.

[Jay-Bruce]

Marc, thanks for the diagram, as always very helpful.

A simple test would be to check for voltage on that line with the engine running, one probe of the meter into the exciter terminal, and t'other on the -ve jump starting terminal in the engine bay. Also worth visually checking the condition of that terminal while you're at it. Given it's ECU controlled, we'd need to establish what voltage we should expect to see on wire 1087, is it 12v as per car electrics, or 5v as per typical electronics?

[Kenmac15]

Update

So my C5 2.7 intermittently had the common Battery charge warning pop up until it finally died 2 weeks ago. So spent day's checking fuseboxes, earth straps & battery to no avail. Took the alternator off & it was in a sad state with oil & dirt, took the voltage regulator off & the bushes were gone, Yes found the problem happy day's.
Fitted a new alternator & felt really good but that was short lived as still had the same warning . So took it off & exchanged it for another one just incase it was a lemon & fitted it today & I still have the same warning. I'm at the point where I'm either going to beat the ever living daylight out of it with a sledgehammer or break it for spares

[GiveMeABreak]

There's one possibility - the Battery Charge Status Control Unit (BCSCU). As you've been having issues until you realised it was the alternator, the BCSCU may still be registering a discharged state of the main battery. It can take a while to settle (up to 4 hours). The status of the module can be read in the in the test parameters section of Diagbox.

Advice is to Charge the battery and clear the fault codes. Then allow the unit to calibrate itself with the new parameters after the battery has been charged.

[Kenmac15]

Update........
Finally sorted the problem & it was the alternators from ECP. So after the 2nd alternator didn't work I found out that the voltage from the regulator was really low, ordered a regulator from ebay & fitted it yesterday & 13.8v immediately.
So the moral of the story is don't assume that brand new parts are OK especially if you've tried 2 of them.
Thanks for all the help

[Hell Razor5543]

Ah. ECP. That was your problem right from the start. ECP have earned the (deserved) nickname of "Euro Crap Parts".

[GiveMeABreak]

Hi Ken, thanks for the update.

Actually, if you had mentioned ECP to start off with, you probably would of had a dozen of us telling you that that would likely of been an issue. Loads of members have had parts form these people that are faulty, dead on arrival or just don't work, including myself on 3 separate occasions.

The only things I would order from them are non-electronic items, like branded discs or pads, but nothing with wires or sensors!

[Paul-R]

Actually, if you had mentioned ECP to start off with, you probably would of had a dozen of us telling you that that would likely of been an issue

LOL! I was in ECP yesterday to buy a tin of Inject Crack and while I was there a chap came in with a a couple of timing belts. I heard him say that they had now supplied two wrong timing belts and this was the original which they had to match. He had lost a day's work because of this.

[GiveMeABreak]

I really don't know how they are still in business. The staff at my nearest branch have faces like smacked a**es , no doubt as a result of constant customer complaints.

[Kenmac15]

Yep absolutely useless which is a shame because when I first started using them 20+ year's ago they were fantastic, also GSF aren't much better now either