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12V battery is exposed to anybody that wants access?

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T

Thud

Member
Jun 25, 2014
349
203
Atlanta
#1
After watching this video:

Tesla Model S Deliver and Complete Walk Around and Drive Part 32 of Many! Nosecone Removal - YouTube


.....it does concern me a slight bit that anybody can just pop the nosecone off (with their fingers or a credit card) and then disconnect the 12V battery with a wrench. Once disconnected there goes any remote monitoring of the car, and disabling any alarm system that might be installed. Somebody could just tow it away.

In any other car, you need to break into the car first and then pop the hood or trunk.

Am I missing something? Is there a mechanism that prevents the nosecone from popping off unless the frunk is opened?


EDIT - I know what I'm missing.... you probably can't get to the actual battery from there (my S85 isn't here yet). So disconnecting the nosecone battery post won't do anything, although somebody could short out the battery if they wanted. Where is the battery physically located?
 
Last edited:
#2
Thud said:
After watching this video:

Tesla Model S Deliver and Complete Walk Around and Drive Part 32 of Many! Nosecone Removal - YouTube


.....it does concern me a slight bit that anybody can just pop the nosecone off (with their fingers or a credit card) and then disconnect the 12V battery with a wrench. Once disconnected there goes any remote monitoring of the car, and disabling any alarm system that might be installed. Somebody could just tow it away.

In any other car, you need to break into the car first and then pop the hood or trunk.

Am I missing something? Is there a mechanism that prevents the nosecone from popping off unless the frunk is opened?


EDIT - I know what I'm missing.... you probably can't get to the actual battery from there (my S85 isn't here yet). So disconnecting the nosecone battery post won't do anything, although somebody could short out the battery if they wanted. Where is the battery physically located?
Click to expand...

Correct, you just get access to the 12V power, but not the actual battery. Shorting it won't do anything other than blow the 50A fuse that powers those posts. The car will keep functioning normally. Worst thing someone could do is try to use your car as a 12V power source. Given that the fuse is 50A, at 12V that's 600 Watts of power which means they'd be able to drain about 2 rated miles per hour, so it's not even a threat of someone being able to drain down your car to zero using those posts.
 
#3
As Pgiralt notes, the 12v battery can't be shorted from the post under the nose cone. It's protected by a very inaccessible 50 amp fuse (I know because I blew that fuse:).

The battery is very inaccessible -- under the passenger side top frunk liner and the piece under it. For someone who doesn't know the car well it's unlikely they'd find it -- no obvious cues. Plus the high voltage connection is there as well. So someone trying to attack the 12v could electrocute himself. Ironic justice there.
 
#5
Thud said:
After watching this video:

Tesla Model S Deliver and Complete Walk Around and Drive Part 32 of Many! Nosecone Removal - YouTube


.....it does concern me a slight bit that anybody can just pop the nosecone off (with their fingers or a credit card) and then disconnect the 12V battery with a wrench. Once disconnected there goes any remote monitoring of the car, and disabling any alarm system that might be installed. Somebody could just tow it away.

In any other car, you need to break into the car first and then pop the hood or trunk.

Am I missing something? Is there a mechanism that prevents the nosecone from popping off unless the frunk is opened?


EDIT - I know what I'm missing.... you probably can't get to the actual battery from there (my S85 isn't here yet). So disconnecting the nosecone battery post won't do anything, although somebody could short out the battery if they wanted. Where is the battery physically located?
Click to expand...

The 12v terminals are fused on a 50 Amp fuse. Even if you short them, you just blow that fuse, car will not be harmed.
 
#6
I think this is a good point to bring up.
Curious wonder if someone say discharged a few KV at high current threw the terminals i.e. the fuse likely will not have time to react before the systems behind it see the HV. Would it affect key subsystems? Security? Drive systems? etc..
 
#7
If the battery did begin to discharge, the HV battery contactor would engage, power the DC-DC, and recharge the battery. I think the DC-DC can supply about 1.5kW, so you would have to draw more than this to discharge the 12V system, which would blow the fuse. It would take you many many hours before the main HV battery was discharged.
If you discharged HV either it will be caught by various transils across the vehicle or it would probably destroy most of the car's electronics, including things like the BMS, which is custom to the pack. So great, you can steal the car, but you can't open the doors, drive it, charge it, or use it.
 
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#8
tom66 said:
... If you discharged HV either it will be caught by various transils across the vehicle...
Click to expand...
Well transils and other HV suppression devices on a PCB can only handle so much before they fail.

tom66 said:
... it would probably destroy most of the car's electronics, including things like the BMS, which is custom to the pack. So great, you can steal the car, but you can't open the doors, drive it, charge it, or use it.
Click to expand...
I don't think chop shops would care.

I would have preferred a reduced the attack surface of the car and have them put the 12v terminal where it's not easily gotten too. Granted it might have involved something silly like manual combination lock.
 
#10
spaceballs said:
Well transils and other HV suppression devices on a PCB can only handle so much before they fail.
Click to expand...

Yes, and since the environment is considerably less harsh than an ordinary vehicle, which can regularly experience harsh load transients (75V positive and up to 30V negative, plus up to 28V continuously for 15 minutes "double-battery jump start") they will be lesser rated.

spaceballs said:
I don't think chop shops would care.

I would have preferred a reduced the attack surface of the car and have them put the 12v terminal where it's not easily gotten too. Granted it might have involved something silly like manual combination lock.
Click to expand...

Depends on what parts they need. Almost every part in these modern vehicles including the Tesla are electronically connected. I mean, you could of course use tyres, chassis parts, etc. You'd need to flat-bed or tow it, which would be difficult with the parking brake locked. But all of the driveline components, and the parts particularly unique to Tesla vehicles, would be destroyed. I've never heard of this type of attack. It would require substantial energy at a high voltage. Perhaps a several kV large capacitor; awkward and very dangerous to carry about.
 
#13
artsci said:
If a chop shop steals the car forget it. There's no stopping those SOBs. The only hope is that they'd electrocute themselves messing with the high voltage side.
Click to expand...

Unfortunately, very difficult. The HV system is not engaged when the car is off. All high voltage cabling uses very visible orange wiring. Disconnecting the 12V battery disconnects HV entirely, containing it within the battery.

ecarfan said:
While I'm sure that someone, somewhere, has tried to steal a Model S, I am doubtful they would succeed and/or have much usable to sell if they managed to make off with it.

I think Model S thefts are probably rare, but I have no data to support that content in.
Click to expand...

This is what happened to the last stolen Model S.
http://kep.cdn.index.hu/1/0/641/6413/64134/6413482_0eef5751295148cd11bdbf09c38d8fe7_wm.jpg
 
#15
tom66 said:
.... It would require substantial energy at a high voltage. Perhaps a several kV large capacitor; awkward and very dangerous to carry about.
Click to expand...
Amazon.com: Philips HeartStart Home Defibrillator (AED): Health Personal Care

- - - Updated - - -

ElSupreme said:
It would be so much easier to let the air out of the tires (or slash them) to disable the vehicle.
...
Click to expand...
What if they wanted to do the most damage to the vehicle, compare 4 tires vs. a bunch of electronics in the car.
For example I find this sad http://www.teslamotorsclub.com/showthread.php/35077-Vandalism
 
#16
spaceballs said:
Amazon.com: Philips HeartStart Home Defibrillator (AED): Health Personal Care
Click to expand...

Extremely difficult to get that to discharge across a non-human target. It requires a heartbeat to be present (you do not use a defibrillator on a stopped heart.)
Energy discharged on the order of a few hundred Joules, sufficient to cause mild damage to non-protected electronics, but could be absorbed by a transil device without failure in most instances.

If you really want to cause damage:
Smash a headlamp or tail-light on any car. Apply your HV there. If it is a modern car, there's a direct path to a body control module or canbus interface. That could be a lot more damaging, as those interfaces are rarely protected.
 
#17
tom66 said:
Extremely difficult to get that to discharge across a non-human target....
Click to expand...
I was noting it's smallness.. I have a few HV caps that fit in a large suitcase, and can do soda can crushing if I wanted too. But you get the idea.

tom66 said:
If you really want to cause damage:
Smash a headlamp or tail-light on any car. Apply your HV there. If it is a modern car, there's a direct path to a body control module or canbus interface. That could be a lot more damaging, as those interfaces are rarely protected.
Click to expand...

Yep but breaking headlamp/tail-light might look more suspicious than just taking off the front cover to connect up to the 12v battery inlet.
 
#18
pgiralt said:
Correct, you just get access to the 12V power, but not the actual battery. Shorting it won't do anything other than blow the 50A fuse that powers those posts. The car will keep functioning normally. Worst thing someone could do is try to use your car as a 12V power source. Given that the fuse is 50A, at 12V that's 600 Watts of power which means they'd be able to drain about 2 rated miles per hour, so it's not even a threat of someone being able to drain down your car to zero using those posts.
Click to expand...

The HV pack has to be "on" in order to recharge the 12V. So they could drain the 12V down to zero, which would immobilize the car until it was boosted.

As others have said, that is the hard way to immobilize a car.
 
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