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Comment by cj | Hacker News Reader

Adding to that, you also can't jump start another Tesla with your Tesla (according to the manual)

Edit: link to jumpstarting in manual: https://www.tesla.com/ownersmanual/model3/en_au/GUID-3567D5F...

Jump start? Pfft. The stupid car, got stuck with AC stuck on full heat, with a blacked out screen. Unresponsive to resets. I couldn't even open the damm frunk to remove the fuses, yeah okay I don't carry a 12v battery around with me to jump the frunk.(how difficult is it to give damm manual overrides for critical stuff) It was a rental so no access to Tesla app. Tesla Customer service refused to help, since it's a rental

Tesla is a smart phone with wheels that can't make calls. It's great while it works but it is as dangerous as it can be once things go wrong. This car must be banned. It scarred me enough to keep me away from other EVs too which put all the controls in a screen. There is no excuse for EVs to have everything electrically controlled.

I agree these situations can be dangerous and frustrating. There is a manual trunk release on the tesla, here's a video https://www.youtube.com/watch?v=b1bJ0F3R0Nc.

I have a rivian and the 12v battery died on it while I had it plugged in charging at home. In the manual I found the emergency trunk release (access from underneath the car), and then there was a manual release for the charging port inside the frunk.

My gas cars have died with some electrical problem before, out in the boonies where there was no one to help. But that was back when all my cars had a key, so I could at least open the door with physical key.

Many EVs still have a physical key to open the car (my EV6 and my wife's ID.4 both do for example)

Well that's great, my Tesla and my rivian do not have physical keys, and I wish they did.

Not the trunk, the frunk. That's where the fuses are located on the Tesla Model Y isn't it? Or were the videos I watched were wrong?

Question out of ignorance: what does it mean to jump start an EV?

I know what it is for an ICE (and I have a jump-starter-battery always in the trunk, with usb ports it doubles as a phone charger if you’re somewhere without power), but for an EV, I’d guess you either have enough battery charge for it to run, or you need to charge, right?

If you need to jump start an EV you need to charge it basically. I cant think of a case where it would be needed with an otherwise filled battery.

I just learned that my ICE vehicle can drain the 12v battery overnight if it fails to turn off the accessories circuit. No lights or infotainment etc. were left on. In my case, it was the switch on the park gear flaked out. I imagine a variety of similar faults could cause the same issue in an EV.

My car (a hybrid) has a long-standing bug in the radio system that can make it "freeze" and stay on forever. Only way out once it's frozen is to pull the right fuse (or wait for it to drain your battery all the way).

Reminds me of renting a zipcar for a few days and parking it in an underground parking lot.

When I went to use the car after a couple days, the battery was drained. This happened on multiple occasions with different vehicles parked in the same garage.

My best guess is Zipcar has cellular comms to phone home, which enter some weird “always trying to connect” state when cut off from cellular signal underground.

Zipcar’s response was to ban me from renting on their platform ever again for too many disabled vehicles.

An EV has two power systems, 12V (typically) for the car accessories, and 120V for the drive motors.

And if the 12V system is down, you can’t drive the car (can’t close the contactor that connects the 120V batteries to the system).

So, in theory, you could jump the 12V system so you can engage the 120V system.

The design that allows 12V to completely discharge while there's charge in high voltage batteries is idiotic. I ran into that in Toyota hybrid. Why there's no manual override that enables charging of 12V battery? It could be under the hood and turn off automatically when the voltage in 12V battery is high enough.

This same problem happens in evs where due to some problem the 12v discharges. When everything is working the 12v is charged up from the main battery bank.

Tesla in the early days sometimes ran down the 12v and it wasn't that uncommon, there were problems with runs of batteries yielding poor ones; I think they had messed up software that wasn't charging the 12v enough, but they made changes to address that long ago. On my second ev, a rivian, I just had to have my 12 battery replaced. They said sometimes the 12v batteries just die on them.

Some Hyundai hybrids and PHEVs have this (I saw it in the original Ioniq). It's a button you press that temporarily charges the 12V battery through the high-voltage system rather than being always enabled, but it seems like a great idea.

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