I’m sorry if I missed this somewhere, but if the 12V is dead, how are you opening the frunk?
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I’m sorry if I missed this somewhere, but if the 12V is dead, how are you opening the frunk?
9V battery you buy from a gas station - one of the last ways EV owner might want to visit a gas station
You want to open the frunk with external power source because 12V battery is dead. Just opening the frunk doesn't fix the problem.
And the problem is: you can't drive the car.
Gotcha. Yeah, that was my point of finding a convenient tiny battery solely to pop the hood. I didn’t mean to imply a 9V would jumpstart the entire vehicle.
The idea was to then have jumper cables or a portable 12V battery with enough power in the frunk.
RayK
Active Member
Wonder if something like this would fit in the frunk?
https://www.amazon.com/ACOPOWER-Foldable-Portable-Monocrystalline-Controller/dp/B01M8LCDN2
Of course it would require a nice sunny day.
https://www.amazon.com/ACOPOWER-Foldable-Portable-Monocrystalline-Controller/dp/B01M8LCDN2
Of course it would require a nice sunny day.
Does anyone know exactly how much is required to get the system started and close the HV connector? I have a portable jumpstart battery that's about the size of an iPhone and thinner than the widest edge of a 9V battery. It has an 8000mAh/29.6Wh capacity with 200A starting current and 300A peak. Do we have any idea if this could get a Model 3 (or even S/X) started?
K-MTG
Sunshade Captain of TMC
I was under the impression that you could only open the frunk from the access port connector (like you did) when the 12 volt battery is dead. That's what I remember Tesla saying; that the frunk could not be opened by a thief attaching an external battery to the access port connector when the car's battery is operational. However you were able to use a 9 volt battery to open the frunk with an operational 12 volt battery, meaning Tesla is wrong. Is this a bug that will be corrected in a future firmware update?
Additional findings:
6.6V is not enough to open the frunk. However, 9.7V from 3 CR2325s in series is enough. Of course, the caveat being "Is this actually powering the latch or just triggering a 9V relay?"
6.6V is not enough to open the frunk. However, 9.7V from 3 CR2325s in series is enough. Of course, the caveat being "Is this actually powering the latch or just triggering a 9V relay?"
I have already provided this information directly to Tesla, so they can either correct the manual or the functionality.
RayK
Active Member
Sounds like you are commanding a MOSFET to switch voltage to the frunk latch.
edit: A 9V battery probably can't supply more than a few 10s of mA.
edit2: Hmm... on second thought... I recently had an adjustable hospital bed that was normally run with AC power. It had a 9V battery that was used as a backup in case the power went out. It was supposed to be good enough (with a fresh battery) to operate the bed through a couple of up-down cycles. Maybe put an ammeter on the 9V battery when opening the frunk to see how much current is drawn?
edit: A 9V battery probably can't supply more than a few 10s of mA.
edit2: Hmm... on second thought... I recently had an adjustable hospital bed that was normally run with AC power. It had a 9V battery that was used as a backup in case the power went out. It was supposed to be good enough (with a fresh battery) to operate the bed through a couple of up-down cycles. Maybe put an ammeter on the 9V battery when opening the frunk to see how much current is drawn?
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Yeah, I have a Smart Lock that physically powers the door latch to open and close dozens of times over months on a handful of AA batteries. I dunno. Why would it run through a MOSFET if the sole point is opening when the main 12V is dead?
Ulmo
Active Member
What about a higher quality replacement battery spec'd for the Model 3/X/S that is something like a safer gel pack or something such? Of course, you'd have to put it into long term mode and somehow secure it to the frunk in such a way that it doesn't cause injury in a crash.
Ulmo
Active Member
Again, take those hall clamps and just measure
There is definitely a diode so current doesn't energize the whole module responsible for the latch.*
Latch mechanism should have a tiny brushless DC motor with huge plastic reduction gear.
It draws little power, but it will spike when motor hits the end.
*What we actually had to have is a transistor, that doesn't allow actuation when voltage on the main side is high.
Again, take those hall clamps and just measure
There is definitely a diode so current doesn't energize the whole module responsible for the latch.*
Latch mechanism should have a tiny brushless DC motor with huge plastic reduction gear.
It draws little power, but it will spike when motor hits the end.
*What we actually had to have is a transistor, that doesn't allow actuation when voltage on the main side is high.
Hah. I’ll get around to clamping the neutral. I’m already spending way too much time on this damn 12V.
stopcrazypp
Well-Known Member
Presuming the 9V still works with 12V battery disconnected, this is great news. The 9V is easy to carry around or hide somewhere accessible from the outside of the car.
The other question is if it works with even smaller batteries like the 12V A23 (these are the ones in key fobs and garage remotes):
Duracell A21/A23 Alkaline Battery (12V, 2 Pack) MN21B2PK B&H
insaneoctane
Well-Known Member
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