Here’s How To Jump Start Another Car With Your Tesla Model 3
Sure, an electric car can assist a dead ICE car.
One of the Tesla Model 3 owners posted an interesting video using the car’s 12-volt battery to jump-start an internal-combustion engine car that had a dead battery.
The video shows the connection and the mission was successful… and here’s something that appeared in comments. Should you jump start the ICE with your BEV (Model 3 in this particular case)?
From the hardcore EV perspective… if the ICE is dead, do not resurrect it. Ok, just joking.
From a technical perspective, jump-starting an ICE car could be harmful to the EV – especially in the winter when there is a need for high amps for cranking. That puts stress on the 12 V battery in the EV (which is a smaller problem) and the DC/DC converter (which is a bigger problem). According to the comments, Tesla’s DC/DC is ready for 200 A, but surges could cause failure at some point and that comes at a cost.
The other issue could be confusion of the software that monitors the 12 V battery.
It’s an important topic because many EV owners will from time to time see ICE with a discharged 12 V battery. There is a safe way to charge the 12 V battery using the Model 3, but of course it’s not quick.
“It says if you must jumpstart with a Tesla you should let the Tesla charge the opposite car and disconnect before attempting to start. Thanks again!”
Let us know what the best practice should be and maybe there should be some training material released for us all to examine and understand.
Here is the discussion:
sss: You’re essentially starting your ICE from a motorcycle battery. You really don’t have access to the juice in the main battery. There’s only a DC-DC converter that keeps the 12V battery charged; it cannot supply cranking current. By jump starting, you are putting the DC-DC converter in jeopardy and also the 12V battery. Also, this will really confuse the software that monitors the 12V pack and could result in a fault. This has happened to other people trying to power their dashcams directly from the 12V battery.
Andrew Reinsma: I understand what your saying but it is still a regular full size 12V car battery with sufficient cranking AMPs to start an ICE. If you check the owners manual under what to do when your 12V dies in a Tesla you’re actually supposed to jumpstart it exactly how I did but in the other direction. It then states once the computer starts up you are to disconnect the external 12V source and put the car all back together. This is letting us know that the cars 12V inverter will charge the battery back up to full. If the car can handle charging a 20AMPh battery all the way back up from cold dead then the stress on an ICE jumpstart should be negligible.
sss: Andrew Reinsma the stress isn’t negligible, contact the service team and they will tell you that you aren’t supposed to jumpstart an ICE car with this battery. The battery is actually a very large point of failure on the car. Also if u really need to do this you would probably be safer disconnecting the battery from the model 3 The procedure to boost the 12v on a dead model 3 Is safe because the purpose is to get the main pack contractors to close and start charging the 12v pack. This is different than pulling current from the pack and the dc dc inverter trying to account for that spike.Andrew Reinsma: sss I did a bunch of reading in on the topic since you commented and you are right. It’s not recommend to jumpstart but the cranking AMPs of the battery is 45 and the cars DC inverter is safe up to 200 AMPs. If I would have done this in the winter I could have hurt my Tesla. Thanks for your input. It says if you must jumpstart with a Tesla you should let the Tesla chrage the opposite car and disconnect before attempting to start. Thanks again!