Returned from 2 week vacation to a dead EV

[jceichner]

I assume it's the 12volt battery since I can't open doors or anything. Completely dead. I accessed the trunk and 12v battery using emergency cable and tried 12v reset for 30 minutes. Anything else to try before having it towed?

 

[Rebel]

Battery charger.

 

[OrangeDream39]

What was the state of charge when you left? Seems like kind of a catch 22, leaving it at 80% for long periods isn't recommended, better to park it at 40%, but it'll stop charging the 12V from the high voltage battery if state of charge falls below a certain level. Maybe there's a "sweet spot" like 60%.

 

[jceichner]

What was the state of charge when you left? Seems like kind of a catch 22, leaving it at 80% for long periods isn't recommended, better to park it at 40%, but it'll stop charging the 12V from the high voltage battery if state of charge falls below a certain level. Maybe there's a "sweet spot" like 60%.

Don't remember exactly but it was below 60% for sure. I'm charging the 12V now, so we'll see.

 

[OrangeDream39]

That's kind of one of the advantages of an EV, the trickle charger is built-in, so hope it's not an issue. I remember it was for the Ioniq 5 when it came out though so there might be a battery management system update or something for yours, or maybe you need a new 12V. The Cybertruck doesn't even have one, just high voltage and 48V. They're quickly becoming obsolete.

 

[Hummerev8157368]

I installed a trickle charger in mine just for this very reason

 

[JackBlack]

Don't remember exactly but it was below 60% for sure. I'm charging the 12V now, so we'll see.

Is this in the manual? I haven't heard of this before.

 

[OrangeDream39]

I used to wonder why I would hear the high-voltage contactors clicking (opening/closing) on my EVs in the middle of the night. It was the BMS charging the 12V. Trickle chargers are for gas cars.

 

[Hummerev8157368]

You can absolutely still trickle charge a 12v on an EV. This is the best way to store the EV if you are leaving it for an extended period. You need to make sure you have the right one though. I use the NOCO genius 5. You can set it and forget until you want to use the vehicle again.

 

[OrangeDream39]

I thought about leaving it plugged into level 1 instead of my faster level 2 charger and just scheduling slow charging a few hours every night. That should force the contactors to close and charge the 12V, if they're not closing on their own to maintain the battery like they should, for whatever reason.