Hi v1rok

While it is Normal for the Charging indicator needle to go down, as the Voltage in the Battery Builds up, it certainly isn't Normal for the Voltage in

the Battery to go down.

So it looks to me that you may have blown a diode in the Alternator, which could seem to indicate that the Battery isn't Charging but instead is running down.

Which is why the 'Lightning Bolt' is staying on.

But lets wait for a Second Opinion from someone with more knowledge of Auto Electrics.

 

Well bloody done.

The voltage will drop when "juice" is being consumed.

The battery mishap would have fried the alternator in less than a heartbeat, so whatever was happening, is now dead and done. The alternator has a direct battery feed, no matter where the ignition key is.

See ya in Vegas later this year.

 

Let me interpret what you'd just said. The reason the voltage was dropping when the car was idling is that whatever electrical current the car needed was being taken from the battery now, instead of the alternator. Did I get it right?

Nothing was really on during all 15min while I idled the car. Except for the radio clock and the light in the boot. I guess both of these don't require a lot of juice to operate, that's why voltage was dropping slowly. Makes sense.

But if I need to drive with lights on (at night) then it will likely drain the battery very quickly...

 

OK,

Alternator diodes are fickle on a good day, and if Lucas labels are anywhere nearby, even more so.

With the engine idling the alternator would possibly not be charging at all. The Lucas, and some Bosch units require at least 1500 engine RPM to "excite" the charging system, then they will maintain a charge of sorts at idle.

A simple "blip" of the throttle is usually enough to get them excited, and when an Alternator "excites" you can definately hear it, like a distant whine.

With the engine at idle you have the following drawing power:

Fuel pump = 6amps.
ECU = about 4 ish amps.
Ignition system = about 6amps
Radio = 2 amps maybe
Clock = 0.5amps
Boot lamps = 2amps.
Interior fan/s on low, = about 5amps.

And so it keeps growing. Kind od scary aint it.

The mishap with the battery cables would have spiked that alternator, no matter what was happening prior to that. They simply are 100% polarity sensitive, and 100% unforgiving.

If it were mine, I would remove that alternator, take it to a reputable Auto Electrician, and have him test in on his bench machine, that is the always the first thing in my book when messing with charging hiccups.

Then those stupid earth straps around the LH engine mount need sorting.

 

Thanks, Grant. Alternator was next on my list anyway. Will start a new thread on it and will document progress with pictures