What exactly do you do when you start an EV? – Jalopnik

You may or may not know that an electric car, in addition to its massive battery pack, has a smaller 12V system to power the auxiliary equipment. Just like what you’ll find in an internal combustion vehicle, the 12V is there to power your EV’s lights, alarm, door locks, and advanced computer brain. The 12V also steps in to prevent voltage fluctuations and protect the electrical systems when the main battery starts to act strangely. It is even responsible for disconnecting the high-voltage system during a crash.

Understand that while it is entirely possible to replace the 12V battery in an EV, you cannot do so against the main battery (and you should never attempt to do so). Either way, the process of jump starting is very similar to what you’ve practiced in the past – at least for the vast majority of electric vehicles. But just to be sure, double check the owner’s manual, just in case. If you’re confused or haven’t started a car before, you can quickly and easily remember the process by using an old saying: “Red from dead to red to good, and black from good to under the hood.”

Before you hit the ground running, though, there are a few EV-specific things to keep in mind. Do not use another EV to jump over the dead as the 12V battery is not designed to support another jump start. Second, disconnect your EV from the charger before switching to 12V. And of course, don’t mix up the colors of the jumper cables; the internet already has a huge library of the calamities that can occur if you do that.

From there, start the donor car (the one with the good battery) and let it run. Once the donor car has been running for a while, get in the EV and try to start it. If the EV does not start immediately, press the power button a few times and leave the EV on for at least 20 minutes. When you’re done, disconnect everything in reverse order, starting with the ground.

Interestingly, the 12V in an electric car is of a ‘deep-cycle’ variety, so it’s not always a one-to-one copy of the battery in your regular car or truck. Unlike internal combustion vehicles, electric cars do not have an alternator; they use trickle charging (via a DC-to-DC converter) to keep the 12V topped up. When you plug in your EV, the computers also use some of the available power to charge the 12V battery.