Clio automatic, red light.

Most modern car manuals advise against jump starting with booster cables, due to the possibility of blowing sophisticated electronic circuits. (Meaning overly complicated). Never heard of a problem yet, maybe you're the first. DaveK.

Sounds like 1 of the 3 phases is still working , so when you ask it do much work there is a net loss rather than a charge. The altenator should give out about 60 amps on full load. steve the grease

So how do they suggest you do it? All the ones I've seen suggest jump starting. It's more likely you've blown 1 or 2 of the diodes in the alternator & the noise has confused the auto controller.

Probably, I looked at the current waveform going into the battery with a scopemeter & current probe. There was probably more ripple than I was expecting, but I have never looked before.

Just to clarify, when I used my Astra to jump start, I did not have the engine on, or the ignition active. I simply connect my battery across the Clio's, although it was still wired to the Astra.

Many years ago I would have had the Astra on tick over, but now I think it's more likely to overload the Astra's alternator, when the Clio starts cranking. I always advise not to jump start someone's car, with your engine running.

I think we'll invest in a recon alternator, the warning lamp is another problem.

Cheers.

Colin.

I had a look at the current waveform, there was some ripple. Maybe a lost diode or two, as Duncan Wood suggested.

Cheers.

Colin.

With your amperage and voltage readings it sounds to me as if acouple of the diodes have blown in the alternator which is showing up under load with the regulator unable to get more juice out of the alternator. The auto box lamp being lit may be caused by this, and / or the voltage spike when using the jump cables, or its suffered a fault from the jump start, or the part A/C waveform its seeing on its power lines is upsetting it.

Try fully charging the battery with it disconnected from the car, then temporarily whipping off the alternator drive belt and seeing if the auto box MIL lamp is still lit when running the engine. If so, extract any fault codes from it and go from there.

Tim..

It's almost impossible to overload your alternator (it's one of those american ideas that they blow up when you recharge a flat battery with them) the regulator & design inherently current limits.

BMW give instructions on how to do it in theirs - and even provide a special terminal for the purpose on the engine - the battery's in the boot.

It could be indicating low volts - many of these electronic autos are quite voltage sensitive.

It is possible to replace the diode pack which is the likely suspect.

Although if you don't already own a big soldering iron the £35 my local alternator shop charges to strip & rebuild them's pretty economic