Model 3 12V system

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JWardell

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#21
We've heard first person that the 12v battery is easily accessed. The remaining question is what continuous 12v current the DC-DC converter will support so I know how large of an AC inverter I can add for tailgating, power outage, camping etc.
 
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4701

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#22
Step one is to measure the big + wire. Which looks like is not very thick.
Though 100A is a safe bet. And that should be enough for pretty much everything that doesn't heat water/air.
Why at least 100A? Well, outer fan is 35-50A. HVAC fan is 20A. Coolant pump 5A, cigarette lighter 15A,
Seat heaters 10A each. EAP computer 10-15A. Wiper motor 10A. Rear+mirror defrost 30A.
And some random loads can add 100A more for a moment, power steering, window&seat motors, audio amp, lights etc.
Though it doesn't mean Tesla isn't using smart load limitations (like BMW does), but likely not necessary.
That should be around 3/4 of the whole thing.

I would die to see wiring diagram:rolleyes:
 

KarenRei

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#23
AFAIK he revoked "new platform" to Y. This only means same body production line and major parts. I still think Model Y will have considerably less wiring. It is possible, it just needs brainpower and lots of integrated microcontrollers, communicating on power lines (which is extremely easy, especially on DC).
He nonetheless added that they still plan to remove the 12V in the subsequent conference call to the one where it was announced that the Model Y would be built on the Model 3 architecture.
 

PaulK

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#24
Has anyone seen a photo of the actual M3 12v battery? Make & model.

Mostly, I just want to know if it comes with an AGM battery (which is lightweight and leakproof).

Paul
 

Sandy

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#25
Has anyone seen a photo of the actual M3 12v battery? Make & model.

Mostly, I just want to know if it comes with an AGM battery (which is lightweight and leakproof).

Paul
Guessing here but as it’s not lithium I can’t imagine today it being anything else but an AGM battery.
 
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#26
...The remaining question is what continuous 12v current the DC-DC converter will support so I know how large of an AC inverter I can add for tailgating, power outage, camping etc.
BTW, in the Model 3 Release Event Elon mentioned the big projector was running off a Model S(or X?) battery. It would be a crazy feature to have a 1-3 phase 120/230/240V AC line output directly from the motor invertor. You could run whatever electrical appliance you wish anywhere you can drive. Huge selling point for future utility car. And the added cost is just few cables, connector and some software, since you already have the invertor.
 

Frank99

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#27
The inverter likely isn't capable of generating 120/230/240V. It's output voltage is likely the battery voltage, with lower power levels created by changing the on/off duty cycle.
 

Model34mePlease

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#29
It would be good if there was some standard way, beyond the 12v power outlet, to convert battery DC to, at-least 120V AC. It could be just a standardized power outlet standard, with inverters sold in the after-market.
 

Badback

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#30
The inverter is capable of generating any voltage up to where the peak is equal to the battery voltage. The main issues are that the inverter is designed to operate into the impedance of the motor and the control algorithms expect to see a speed feed back from the motor.

There is much more, but I won't bore you with the details.

A completely separate, purpose designed, inverter operating off of the battery would be a more likely approach but would be quite expensive.
 

Frank99

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#31
Actually, I'd love it if you bored us with the details.

What you're proposing " capable of generating any voltage" is, to the best of my knowledge, a much more complex inverter design than one with a fixed peak voltage (400V) and variable duty cycle/PWM. Unless, of course, we're describing the same thing, with you speaking in terms of "average voltage" and me in terms of "instantaneous voltage". A 500 hp motor won't care about the difference, but a 120V electronic device would.
 

Badback

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#32
Actually, I'd love it if you bored us with the details.

What you're proposing " capable of generating any voltage" is, to the best of my knowledge, a much more complex inverter design than one with a fixed peak voltage (400V) and variable duty cycle/PWM. Unless, of course, we're describing the same thing, with you speaking in terms of "average voltage" and me in terms of "instantaneous voltage". A 500 hp motor won't care about the difference, but a 120V electronic device would.
OK. The switching devices in the inverter have a peak current rating that should not be exceeded. The rate of current rise during each inverter pulse (di/dt) is a function of the motor impedance and any other impedance the inverter may have internally. If you tried to operate the inverter into something with significantly less impedance, you risk damaging the inverter. This is besides the instantaneous current limit circuit in the inverter which may or may not be fast enough to shut down the inverter depending on the load.

There are many more reasons, but my fingers are tired.
 

JWardell

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#33
BTW, in the Model 3 Release Event Elon mentioned the big projector was running off a Model S(or X?) battery. It would be a crazy feature to have a 1-3 phase 120/230/240V AC line output directly from the motor invertor. You could run whatever electrical appliance you wish anywhere you can drive. Huge selling point for future utility car. And the added cost is just few cables, connector and some software, since you already have the invertor.

Tesla can do what they want. They have any access they need and full design details. For all we know the projector was running off the 12v system anyway. If we were given direct access to the battery then we could design a powerful inverter fro 120v AC. This is, afterall, exactly what is in the powerwall systems.
But it is very dangerous to allow access to the 400v and near infinite current of the battery. Several levels of safety are there to prevent it. Any connection becomes a huge issue in a device that has a decent chance of being crushed in an accident.
Of course Tesla can hack their car in any way. The same can not be said for us electrical hackers that like to do creative things with our most expensive gadget.
 

Timotion

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#35
Interesting posts!....It seems that Tesla Model 3 has the main dc-dc converter inside the main battery behind the contactors which was not the case for Model S/X and the vampire load (load when the vehicle is on off-state) is supplied by the main battery..Can someone someone confirm that?
 

PaulK

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#36
Guessing here but as it’s not lithium I can’t imagine today it being anything else but an AGM battery.
Unfortunately it seems confirmed that the 12V battery is a lead acid battery with a vent. Manufactured in Korea. See the images of it in this video:

This video shows how the frunk area is separate from the front motor area.
 

Sandy

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#37
Unfortunately it seems confirmed that the 12V battery is a lead acid battery with a vent. Manufactured in Korea. See the images of it in this video:
What else would be other than lead acid?
 

Frank99

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#38
Lithium ion, specifically lithium iron phosphate, would seem to be a good alternative. Obviously Tesla has good battery engineers, so i assume that lead acid still has better characteristics.
 

PaulK

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#39
What else would be other than lead acid?
Sorry, I meant it seems to be a wet cell vs. lithium battery or at least AGM (which is lighter, has a longer service life and tolerates discharge cycling much better).

EDIT: I've been trying to research what this battery model actually is, and I can't determine for sure that it's not an AGM battery. It looks large for an AGM and has a vent/breather tube. But I've just read elsewhere that some AGM batteries do have breathers. Can anyone determine the chemistry of this battery?

Paul
 
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#40
Sorry, I meant it seems to be a wet cell vs. lithium battery or at least AGM
It does appear to be regular wet cell. Don't know why. Seems weird. Though Model S/X AGM's have a high failure rate anyway.
Maybe they try regular wet cell. At least it appears they have a serviceable version.
Though it's weird they use random battery maker.

LiFePo needs more research. I bet Tesla doesn't want to try new stuff with mass market vehicle.
Whatever they choose, 12V battery should last a decade if used correctly (like with solar installations).
It's all about 12V DC-DC inverter software.