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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 us

by fipar 3y ago

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?

deleted 3y ago
[deleted]
giancarlostoro 3y ago
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.
- raisedbyninjas 3y ago
  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.
  - zerocrates 3y ago
    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).
  - cj 3y ago
    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.
falcolas 3y ago
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.
- scotty79 3y ago
  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.
  - rnk 3y ago
    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.
  - sgerenser 3y ago
    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.

by fipar 3y ago

deleted 3y ago

[deleted]

giancarlostoro 3y ago

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.

raisedbyninjas 3y ago
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.
- zerocrates 3y ago
  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).
- cj 3y ago
  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.

falcolas 3y ago

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.

scotty79 3y ago
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.
- rnk 3y ago
  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.
- sgerenser 3y ago
  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.