996.2 Electrical Question :

So awhile back (nearly two years!!), I came home from a weekend away and discovered that my 911 battery had leaked all the way down the driveway... Seems that possibly something was drawing down the battery while the battery tender was trying to keep it charged and basically cooked the battery - the battery case exploded, hence the river of nice clean concrete on the driveway... cleaned it all out, hosed down the car, lots of baking soda, etc. Not too much residual damage that I can find anyway... Anyway, life got in the way so just now starting to try to get the car back on the road... Trouble shooting question: There's currently no battery in the car : Would you expect to have a full short from the positive battery terminal to ground when you turn the ignition key to the on or start position? There's nothing showing on the meter with the key off. I'm planning to replace the battery over the weekend and go from there...

There is never a case when a good car would show zero ohms from the battery positive cable without the battery. My guess is your alternator is toast and the diodes / regulator are shorted to ground. That would also explain why your last battery blows up. It was being asked to supply infinite current to a short. Do not install a battery until you figure this out.

@yelcab I started out thinking along those lines but when I pulled the alternator and disconnected both the hot and the control wires from it, I was still reading a dead short from the hot lead back towards the front of the car. I pulled the power distributor from under the dash and disconnected the battery hot - same thing, still a short towards the fuse panel. The fuses are intact, nothing melted or discolored. I pulled each of the wires on the power distributor separately to test to ground and it was the center F4 red/wht wire that goes to the ignition switch that had the short. I then realized that I'd left the key in the car (apparently in the on position) and once I removed the key, the short went away. Put everything back together and when I turn the key, it's a complete short to ground measured from the hot point beside the power steering reservoir. Alternator and all wiring back in original configuration. Not sure how best to test next steps... I'm using a Fluke multi meter using the ohms/beeper to trouble shoot...

Electrical engineer here. When you pulled the hot wire off the alternator, you still had a direct connection from the starter to the hot/jump point beside the power steering reservoir. If you are really getting 0 ohms on the meter (make sure meter is on the lowest Ohm setting. Don't use the beeper) then the starter solenoid/starter is the problem.

Yep, don't use the diode test, it will beep up to something like 15 ohms or so. You have to read the meter.

Third time: don't use the beeper....

So, the summary is.. Key off, resistance from battery + cable to ground is infinite. Ken on, resistance from battery + cable to ground is zero. Is that it?

<<<50+ years being a Tech...not an Engineer per se but know a thing or two and smarter than the average Bear... I think that what you are seeing is not a "short' but rather a "consumer" ... The 996 even with everything turned off and key out will have "consumers" such as radio , window motors, seat motors, engine controls, sun roof motors, the list goes on , they all have "memory" in ROM , RAM , DRAM ,KAP ,with capacitors that need charged up... When you first connect a battery ( or meter) with all the consumers with dead/uncharged capacitors the current will be as high as 5 amps ...5 amps equals 2.4 Ohm in a 12v system...Note : this is not a "SHORT" this is just the "consumers " charging up .. After the capacitors are charged up and the system goes to sleep the "consumers" will still pull about 30 milliamps ...30 milliamps on a 12v system is 400 OHMS... I think you are using the wrong procedure here ..and it has you thinking down the wrong rabbit hole.. Just hook up a battery and place an amp meter in series to see the amperage... It may spike to 5 amps sharply at first connection but come down to about 1 amp the eventually down to 30 ma ...If you are really concerned there is a short then just place a 20amp fuse temporarily in the circuit with the Amp Meter for added protection... PS;;FWIW I like Fluke Meters as they are top of the line, but what I don';t like is 90% of them are auto-ranging.....While this is great for the Pro that using them daily , it is a big problem for a Novice Troubleshooter that only uses them every 6 months.....Like if you are expecting to 20-30m Ohms.. and the meter shows you 20-30k Ohms at quick look you might think the reading was OK..where as if you had selected the m range you would get an "off scale" reading....With Novice-troubleshooters you will do much better with Manual Range Selection Meters.. Anyway all modern cars act like they have shorts in them when it is just Electronic Power Consumers.....Truth is they never really "turn off " !!!

A functioning battery tender is designed to maintain an optimum voltage not to boil the water out of the stored battery. Op hasn�t said what tender he�s using. but Im guessing the charger is over sized or faulty.

Yes, that's it.

I removed the wires at the hot/jump point; still ha da dead short towards the front of the car...

Understood on all the sleeping 'consumers" but the car hasn't had a battery in it in over two years, I doubt very much there's any residual left in anything...

It's the original Porsche battery tender... Haven't plugged it in to anything since but I'll get around to testing it here in the next few days hopefully...

Batteries usually Explode due to internal cell shorting....each cell has 2.1v and there are 6 making a total of 12.6v ,, when a cell is shorted the battery becomes a 10.5v Battery and any 12v charger will over-charge the other 5 cells and cause gassing ....This gassing is explosive and all it needs is a spark, then BOOM......

@colmfmurphy well did you find a "Short" or was it just the normal load from all the "memory" on the 996 Electrical system??