Strange noises on the right from the engine room-complete breakdown of the power supply DURING the trip.

Hello, with my 2.7/2000/SG occurred yesterday while driving a medium catastrophe - driving / drove currently with voltmeter, therefore accurate documentation

The voltage dropped successively from 13,5/14,0V to 6,4V while driving and the car finally stopped at the end- Light (Litronic) already reduced to "Funzelniveau", dto. the rest of the supply.

Lights in the dashboard on, esp. battery incl. ABS, TC, airbag, spoiler and roof....

It smelled in the back RIGHT (at the air outlet)- there it was an hour later still increased warm / hot - and in the interior slightly after caked rubber.

Everything is dead as a doornail!

Engine ran until standstill inconspicuously, (engine) temperature dto...

Battery in the mid-range bull hot (3J old Bosch S10, just charged and in itself fit, without findings to date)... cooled also not really. Battery in the consequence for safety reasons completely disconnected and towed at night VORSICHTIGST over secondary route...

I suspect the already once replaced LiMa or regulator of the same (to KOKELN started?) and ggfls. more... Yesterday on today I had still reloaded, outward journey was completely problem-free inconspicuous and without special incidents.... Home trip irres spectacle, which one would not like to experience again....

Can anyone help?

Also had the feeling that the tinsel began to glow when fan originally switched on and this, or the area made something strange undefinable noises, which one could also perceive inside quieter but not exactly allocate / locate...

Suspect a cable also in addition or contact bridge/ extraneous current or the like through? Overvoltage? no fuse flown...

THX...

Quote from wayne

Voltage measured with engine running?

Should be between 13.4 - 14.5V.

It is best to switch on a consumer...

yup- was initially at the start of the journey in the range- THEN SUCCESSIVE down to 6.4V.... (reverse and OFF)

Quote from boborola

Quote from Panaökologisch

yup- was initially in the range at start of drive- THEN SUCCEEDED down to 6.4V.... (reverse and OFF)

What would certainly be interesting- why did you have the voltmeter on while driving?

It's rather unusual - was there any "initial suspicion" of anything here that you wanted to analyze?

I do from time to time when he is not driven so insanely much wg. driving park competition ... and he does not have something like that in the board ex factory...

Quote from Aquarius

If the voltage dropped sharply, not only did something smell in the engine compartment, but also the battery became "hot as a brick" (it wasn't Banner, but Bosch...), this means that the battery and components in the engine compartment were electrically overloaded.

If a fan is mechanically (partially) blocked and draws too much current, the fuse will blow before anything bad happens.

Possibility 1: First, there has been a cell short in the battery. Not uncommon with old batteries.

When a cell shorts, the KLemmen voltage of the battery goes down to about 10 V - 12.0 V. Then, in order to keep the voltage at 13.6 - 14.5 V, the generator will push in proper current. Then the generator will also have a problem.

Possibility 2: The generator has primarily a problem (regulator, diodes) and does not deliver what it should (current, ripple). But this does not explain why the battery has become hot (only in the partial range !).

If diode(s) are defective, the battery can discharge via the generator winding, with high currents. This would explain why the battery did not cool down (at first, eventually).

Since it was driven until everything broke down (6.4 V is at most 1.2 V per battery cell ), both the alternator (at least regulator with diodes) should be due, as well as the battery.

Also possible: corroded/damaged cable connections, ground connections. The starter motor is also connected to the B+ cable to the alternator.

Then what the voltmeter reads, or what the alternator regulator regulates, may not be what is authoritative.

This is an extensive work program for the electrician.

Measure through alternator, especially diodes, connect battery, measure current, voltage drops on cables.

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Thanks a lot- got a new Lima and V-ribbed belt... then possibly the battery- is the fan on the right or its control / power supply otherwise conspicuous?

Battery is actually not old: Bosch s5 010 v. 4/19- with Lima 150A so far from 2015.

thx

So- it is done:

new Lima (incl. Regulator) from 987/997 with 150 A instead of 120 A from the factory (I've done 7J already once so ...) wg. large sound system ... from Jehnert: Soundboards & 2 Way 986 with lots of Stromzieher (Radio Becker Traffic Pro HIGHspeed BE7820 (pull with pleasure!), BT/FSE unit behind it, 500 W Helix AMP (already once at Audio Fischer overhauled & repaired) plus 300W Eton AMP f. rear) and known problem of the anyway chronic undersupply with power ex factory in the 986/996:

https://www.ebay.de/itm/203036…3D%7Ctkp%3ABk9SR-C5-efdYA

By the way, can be purchased cheaper on their HP directly.... No swap... Bosch was too expensive for me at 600-720.-, especially since that is ultimately also only more Chinese scrap... as I had to find out at the IAA...

The one before was obviously not good enough... no idea anymore where I got it from...

Belt to be on the safe side after 7J renewed again (15.- Conti)- but would def. NOT have been necessary...

Bosch S5 has survived the madness, 1x 10A fuse of a power amplifier Eton 300W (small rear) had to be replaced as well... was flown...

Quiescent current 0.006 Ah...

Yesterday 50KM test drive- again everything topp- was the LIMA or its regulator...

What I had forgotten: Ground connections (especially battery / body) / cables, etc. were all i.O..... this problem I had already times with the Cayenne 955...

Thanks to the community...