Can you charge a dead 12v using "cigarette lighter" port

[garrity]

A friends Model 3's 12v gave out on him at work with no warning. Had to get his wife to pickup a new battery and drive 40 miles to get it to him.

Would a portable battery charger plugged into the Model 3's cigarette lighter port solve the problem of driving home without a new battery?

Alternatively, would just having someone with jumper cables and an Ice vehicle be enough to get the frunk open (via tow hook port) and Model 3 12v battery charged up enough to get home?

Also, what is the best way to check the 12v's condition? Can you use a multimeter?

I'm only a few months behind my friend in ownership

thanks

https://www.walmart.com/ip/Portable...MIqOzCw-ST7AIVGR6tBh131g3tEAQYDSABEgLyR_D_BwE

 

[Lloyd]

Only if you lighter port has been wired to be active (hot) all the time. There is a thread describing how to do it with a jumper.

 

[Gasaraki]

Pop tow hook circle, pull out wires, plug in 9V battery, frunk pops open. Jump start battery normally like an ICE car. Profit.

 

[lUtriaNt]

yes you can use a meter to test it.

use the tow hook method to unlock the front trunk.

invest in a portable jump box.

install a battery module on the battery so you know its state of play at a moments notice.
Low cost way to monitor your 12V Battery

invest in a lithium battery like ohmmu.

 

[Sophias_dad]

If you have a jump pack you don't need the 9V to open the frunk, just use the jump pack.

If you have the jump pack, open the frunk and just connect direct to the 12V battery. Once the car is woken up, I believe I read that the HV battery will be supplying the 12V source anyway(until it gets parked).

 

[user212_nr]

A friends Model 3's 12v gave out on him at work with no warning. Had to get his wife to pickup a new battery and drive 40 miles to get it to him.

Model 3 12v battery does not need to be charged in the normal operating conditions. Tesla does all the charging and monitoring, and will warn you if the battery is failing.

The problem should be solved by the new battery, and I think your friend made a mistake by contacting his wife rather than Tesla roadside assistance and using Tesla's service center to provide the new battery. Why involve his wife in such a journey when Tesla was ready to pay, and besides that they can look over the car for issues.

I'm only a few months behind my friend in ownership

In case its not clear, don't worry about it. Its just a defect covered by warranty. You have a warning in the car unless its a sudden failure, Roadside Service, and Warranty Service. No action needed on your part.