# Connect air compressor directly to 12v battery?



## Anthonyb (Dec 31, 2017)

Hi all,

I have an air compressor that connects directly to the 12V battery:

https://www.viaircorp.com/portables/88p

Any idea whether this would be safe to use hooked up to the battery in the (any) Tesla? The instructions say to start the engine prior to using the compressor, but obviously can't do that in the TM3! The amp draw is 20 amps.


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## GDN (Oct 30, 2017)

I just bought a small compressor this past week from Amazon. I really liked the viair products, but skipped them because of the draw and noted they suggest the car should be running. I have no way to control that. I hope it works well for you, I might still upgrade, but for now bought one that says it has 10 to 15 amps. Hope mine will run OK plugged in to the cigarette lighter. 

Also are you aware of what it takes to get to the battery? You have to take the lining out of the frunk don't you? I might be mistaken about that.


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## John (Apr 16, 2016)

I think you'd be MUCH better off getting a little compressor that runs from the cigarette lighter. Those are limited to 15A, and you don't bypass any car systems. I just bought one from Amazon for $37 for my car.

I DON'T KNOW that the car is smart enough to keep you from running down the 12V battery from the cigarette lighter-could be, possibly, maybe-but I DO KNOW that if the 12V battery does run down too far your car is bricked. As in: call a tow truck now.


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## Anthonyb (Dec 31, 2017)

Hmm. Thanks for the feedback - that's the one thing I am worried about (bricking the 12V) especially with the early wear on some of the 12V batteries already. Was kind of hoping that the management system would be good enough to feed current from the high voltage pack to the 12V system but I don't actually know anything about how it works. 

I hadn't thought about the frunk cover removal (I pick up my car today). Probably not a big deal but would be nice to not have to deal with it everytime I needed to add air to the tires (or in an emergency).


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## John (Apr 16, 2016)

Anthonyb said:


> Hmm. Thanks for the feedback - that's the one thing I am worried about (bricking the 12V) especially with the early wear on some of the 12V batteries already. Was kind of hoping that the management system would be good enough to feed current from the high voltage pack to the 12V system but I don't actually know anything about how it works.
> 
> I hadn't thought about the frunk cover removal (I pick up my car today). Probably not a big deal but would be nice to not have to deal with it everytime I needed to add air to the tires (or in an emergency).


Popping the battery cover off is pretty easy, and given that you wouldn't do it that often not a big deal, assuming you didn't break a clip or anything.


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## GDN (Oct 30, 2017)

Anthonyb said:


> Hmm. Thanks for the feedback - that's the one thing I am worried about (bricking the 12V) especially with the early wear on some of the 12V batteries already. Was kind of hoping that the management system would be good enough to feed current from the high voltage pack to the 12V system but I don't actually know anything about how it works.
> 
> I hadn't thought about the frunk cover removal (I pick up my car today). Probably not a big deal but would be nice to not have to deal with it everytime I needed to add air to the tires (or in an emergency).


I can't give you many details, there are a lot of smart people on this forum that can, but the 12 v battery recharges from the high voltage battery as needed. I don't know what happens if you hook directly up to it, the charging system might kick in.


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## JWardell (May 9, 2016)

I've had a few "high draw" air compressors (one from harbor freight, one from amazon) that plug into the lighter socket. The reason they recommend running the engine is because they will draw less current at 16V than at 12V. Without the engine running, I've had them blow the 15A lighter socket fuse in my car. 
At least the model 3 doesn't have fuses and I think supports 20A to the lighter so I think they will be fine. I'll find out soon.


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## Defjukie (Sep 28, 2017)

I wish we still reserved the term "bricked" for when a device was actually irreparably broken.

Having to replace or manually recgarge a 12V battery is certainly inconvenient, yes. But the car is not "bricked".


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## Guest (Jul 22, 2018)

20amps is likely the starting current and draw is up to 10A. It's fine to use for 5 minutes even with vehicle off.
Though it is recommended to "start" the vehicle. In case of Tesla, that means putting vehicle into "Ready" mode.
That enables DC-DC 12V battery "charger" so it will never "run out".


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## PNWmisty (Aug 19, 2017)

GDN said:


> Also are you aware of what it takes to get to the battery? You have to take the lining out of the frunk don't you? I might be mistaken about that.


To get to the 12V battery in the Model 3 takes about 5 seconds, no tools required. Just pull straight up on the dust cover rearward of the frunk tub. It's held on by about 8 large round clips that release when lifted upward.


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