Charging your Tesla is a top priority. You can’t get into your car if your 12V battery is completely flat. If your High Voltage is flat, you can’t go anywhere. The question is can you jump-start it to get moving? I’m a mechanic and will show you when and how to jump your car.
Tesla can be jumped if the 12V battery is flat. The High Voltage battery can’t be charged using jump cables.
In this article, we’ll look at when you can use jumper cables and the different types of batteries in your Tesla.
Using Jumper Cables on Your Tesla
Every Tesla has two batteries, a 12V, and a High Voltage battery. The 12V battery controls your car’s auxiliary areas: locking, unlocking, lights, windows, and the touch screen. So although it’s not running the car, you could be in quite a pickle without its power.
The High Voltage, on the other hand, allows the car to move and drive, but they are very different systems, and if your high voltage is flat, no amount of jumping will get you driving again.
Jumping Your 12V Battery
There are a couple of reasons why you might find you have a flat 12V battery which will require a jump charge
- You’ve left lights or media on with no power running
- 12V is at the end of its life
- Haven’t used your Tesla in a while
Any of the above will leave you with a flat battery and some puzzling.
Locating Your 12V Battery
Unless you are very much into cars and how things work, you probably are not 100% sure where your 12V lives. Don’t worry; most people don’t. Your 12V battery lives in the trunk area, but with no power, how do we open the frunk to jump the battery?
Tesla thinks of everything.
Depending which Model you own will determine how to open the frunk latch. In recent years Tesla has placed access leads in the tow circle at the front of the vehicle.
To release the frunk latch, follow these steps:
- Locate a power supply, i.e., a booster pack
- Release the tow cover by gently pressing on the top left of the circle
- Two wires should be visible: One Black and One Red (Either can be attached to the tow circle)
- Gently pull the cover and two wires toward you
- Connect Red to Red and Black to Black on your booster pack
- Turn on the booster
- The latch should immediately release
Now that the frunk is open, you can continue to locate your 12V.
On older Models, the latch releases are behind-the-wheel arches. You must gently pull the covers away to locate the pull cords.
At the top of the frunk is a dust cover. Remove this by pulling upwards. Small clips are holding it in place. Under this, there is a smaller cover; you must also remove this. You should now be able to see your 12V.
Like before, join your Booster pack, Red to Red and Black to Black.
If you have an S, you must pull the connector housing to the left and remove the cover from the red jump post before connecting the Red to Red and then Black to any metal component on your car.
Begin the charge.
This can take up to 10-15 minutes, depending on how flat your 12V is.
You should now be able to start your car.
If it doesn’t start up, give it another 10 minutes. It might need more time if you haven’t used your Tesla in a while.
If it doesn’t look like it wants to start, then, unfortunately, your 12V may be at the end of its life, and you will have to purchase a replacement.
Remove the Jumper cables in the reverse order.
It’s important to note that you shouldn’t jump your Tesla from another Tesla or EV. You can do irreparable damage to the computers. If at all possible, use a Booster pack and not an ICE vehicle.
Charging Your High Voltage Battery
There are only three ways to charge your high-voltage battery.
- Level 1 charger
- Level 2 charger
None of these involve jumper cables. In reality, there is no way to connect jumper cables to the High Voltage battery, and no attempt should be made to try.
You most certainly will destroy your High Voltage and could cause serious injury to anyone involved.
Model S and X 12V Battery
In late 2021 Tesla launched their new 12V battery for the Model S, and the Model X. Instead of the traditional acid-filled old battery, the S and X now have Lithium Ion batteries.
Although still listed as a 12V, they are, in fact, more like 16V.
Tesla had some issues with their original 12V (which is still installed in the Model 3 and Model Y). They just weren’t going the distance. A traditional 12V should last about 3-4 years, but some of the S and X batteries were failing much sooner.
This was not a good look for Tesla, as, after all, they are a battery manufacturer, and so they decided to replace the 12V with the new Li-Ion.
The new version is incredibly light, at only 1.8kg, compared to the acid battery at 18kg. It also has a much higher capacity which, in theory, should mean that you never have to jump it. It also behaves much better in extreme climates, from -10C to +45C.
The Li-Ion draws energy from the high-voltage battery. If, for any reason, it does go flat – you’ve been away for an extended period, or you haven’t charged the high voltage in a while- there is still the ability to jump the new battery.
We access it similarly and attach the jumper cable to the red by removing a cap on the jump post. The black cable is then clipped to any metal point in the trunk. And the booster pack is switched on as normal.
Other posts you might find useful:
Here are a few common questions folks ask about Teslas:
I’ve written a ton on common Tesla issues, which hopefully you won’t ever experience, but if you do, we have you covered with these posts:
- Is it better to charge a Tesla slowly?
- Tesla won’t charge in the cold
- Why is my Tesla charging slowly?
Check out the Tesla charging page for common Tesla charging problems.
Check out the Tesla troubleshooting page for problem Teslas.
Check out the Tesla category page for a list of popular Tesla posts.
If you are curious about other EV models, check out the EV FAQ category.
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