electrical vehicles often have two battery systems - a 12v, 24 or 48v battery for the accessory systems like your windshield wipers and radio, ECU, door locks, windows etc - and the high voltage power system that runs the motors.
why not run it all on the high voltage system? tbh, I think we’ll get there eventually, but atm it’s easier to isolate them from each other so you never get 400v going to the driver window or other accessories. For the last 100ish years all these systems - motors for windows, wipers, seat adjustment etc all ran on 12v. Auto manufacturers redesigning everything from the power perspective didn’t make a lot of sense when it’s all available off the shelf if you can feed it 12v. And considering the vagaries of charging the high voltage systems, having a separate 12v means even if the fancy shit goes tits up, you should still be able to unlock the door or turn on the hazard lights.
IIRC Hyundai even has a crossover circuit that you can engage to allow you to jump the low voltage system off the high voltage pack, but I have no firsthand experience with this.
I’ve jumped a Tesla (Model S I think) a few times. It’s actually pretty easy. Just pop the grill off with a credit card and there’s jump points there. Once I jumped it, the main charging system would be available for use. Plugging in the main charger then keeps the 12v battery charged and you’re good to drive again. This I believe is a well engineered system and Tesla made it easily accessible.
The dumb part is that until you do that, there’s no way to access the vehicle. No backup key. So if the car dies completely, there’s no way to access the cabin, trunk, or hood.
Yeah, my Leaf has a battery, and if the leads get corroded I can’t start nor charge my battery. It sounds weird, but afiak most electric cars are setup this way.
Yes! EVs still have a smaller ordinary car battery in them. It charges from the main battery in the same way in a ICE car it will charge from the alternator. If the main battery is dead, or just for some reason not charging the small battery, it can effectively act exactly as if an ICE car has a dead battery.
Fun fact, you can also use that fact to use existing car battery to mains power gadgets in the case of a home power outage without the more complex dedicated reverse-charging that only some cars (and chargers) support, but without running an ICE in/outside your house for hours.
Really? Setting up a pure sine wave inverter 48VDC to 115VAC/60Hz (or 220VAC/50Hz) is all one would need to do to supply single-phase mains to a home via EV? I guess it could depend a lot on the rated current capacity of the circuitry between the EV’s Li-Ion main bank and the 48VDC secondary battery.
1kW ain’t too bad for a short emergency. I was bummed when I found out the Greenworks 80V inverter maxed out at only 300W, since I had a nice collection of 80V yard equipment batteries.
Yeuuup.
Gotta be able to turn the car ‘off’, and if the car is off (disconnected contact loop to engage the big battery) it cant receive the signal to turn on. (Connect the contactor to engage big battery)
So something has to always be on.
Which makes the big ‘fuel’ battery into a fancy alternator to keep the 12v/48v stuff on and running lol.
If you disconnect the tiny (in comparison) 48v battery from the main battery it wont charge and the car dies even if the big battery is fully charged.
Long story short, teslas fail to modern car problems but with the added bonus of failing to other dumb tesla-specific problems.
Seeing a heavy duty diesel tow truck haul a cybertruck is about as on-the-nose as you can get for the reason it sucks.
Lol when I get out of my car I park in the garage and plug it in. It stays plugged in till I need to drive again. No charging schedules since they shut down the 3G networks because reasons
The battery that does the driving is completely different from the battery that does the rest of the stuff in the car. So whilst it sounds funny, it’s actually correct.
This is not a unique Tesla thing BTW, I think all electric cars work like that. The battery that does the driving has very different requirements, so keeping them separated is the best solution.
What is pretty shit from Tesla is the regular battery dying all the time. That’s a pretty unique Tesla issue.
The original telsa roadster used the main battery for everything, but it was proven a bad idea because any faults in the battery would leave the car completely dead with no lights or anything. Having a second reliable battery is simply good saftey redundancy.
I’m sorry. They tried to jump start their battery powered vehicle?
electrical vehicles often have two battery systems - a 12v, 24 or 48v battery for the accessory systems like your windshield wipers and radio, ECU, door locks, windows etc - and the high voltage power system that runs the motors.
why not run it all on the high voltage system? tbh, I think we’ll get there eventually, but atm it’s easier to isolate them from each other so you never get 400v going to the driver window or other accessories. For the last 100ish years all these systems - motors for windows, wipers, seat adjustment etc all ran on 12v. Auto manufacturers redesigning everything from the power perspective didn’t make a lot of sense when it’s all available off the shelf if you can feed it 12v. And considering the vagaries of charging the high voltage systems, having a separate 12v means even if the fancy shit goes tits up, you should still be able to unlock the door or turn on the hazard lights.
IIRC Hyundai even has a crossover circuit that you can engage to allow you to jump the low voltage system off the high voltage pack, but I have no firsthand experience with this.
I’ve jumped a Tesla (Model S I think) a few times. It’s actually pretty easy. Just pop the grill off with a credit card and there’s jump points there. Once I jumped it, the main charging system would be available for use. Plugging in the main charger then keeps the 12v battery charged and you’re good to drive again. This I believe is a well engineered system and Tesla made it easily accessible.
The dumb part is that until you do that, there’s no way to access the vehicle. No backup key. So if the car dies completely, there’s no way to access the cabin, trunk, or hood.
Yeah, my Leaf has a battery, and if the leads get corroded I can’t start nor charge my battery. It sounds weird, but afiak most electric cars are setup this way.
Yes! EVs still have a smaller ordinary car battery in them. It charges from the main battery in the same way in a ICE car it will charge from the alternator. If the main battery is dead, or just for some reason not charging the small battery, it can effectively act exactly as if an ICE car has a dead battery.
Fun fact, you can also use that fact to use existing car battery to mains power gadgets in the case of a home power outage without the more complex dedicated reverse-charging that only some cars (and chargers) support, but without running an ICE in/outside your house for hours.
Really? Setting up a pure sine wave inverter 48VDC to 115VAC/60Hz (or 220VAC/50Hz) is all one would need to do to supply single-phase mains to a home via EV? I guess it could depend a lot on the rated current capacity of the circuitry between the EV’s Li-Ion main bank and the 48VDC secondary battery.
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As an example, https://arstechnica.com/gadgets/2025/03/old-bolt-new-tricks-making-an-ev-into-a-backup-power-station-with-an-inverter/
12vdc for a Chevy bolt, with the caveat that it maxes at 1500w so only use a 1000w inverter.
It’s not a great way to do it, but it does work.
1kW ain’t too bad for a short emergency. I was bummed when I found out the Greenworks 80V inverter maxed out at only 300W, since I had a nice collection of 80V yard equipment batteries.
That blows, they’ve got 500w inverters for the 24v & 40v batteries, but only 300w for the 80v
Well, when you know you’re sitting on ~60kw of battery, it’s a bummer. The reverse feed system some cars have is promising though.
Yeuuup. Gotta be able to turn the car ‘off’, and if the car is off (disconnected contact loop to engage the big battery) it cant receive the signal to turn on. (Connect the contactor to engage big battery)
So something has to always be on.
Which makes the big ‘fuel’ battery into a fancy alternator to keep the 12v/48v stuff on and running lol.
If you disconnect the tiny (in comparison) 48v battery from the main battery it wont charge and the car dies even if the big battery is fully charged.
Long story short, teslas fail to modern car problems but with the added bonus of failing to other dumb tesla-specific problems.
Seeing a heavy duty diesel tow truck haul a cybertruck is about as on-the-nose as you can get for the reason it sucks.
Same thing happens with the Nissan Leaf, it has a 12v battery and it needs to be in good shape to start the car.
Frustratingly my phev ford did the same thing when I left it parked for a week, even with the evse attached
Yeah it’s weird that they didn’t include something to also charge the 12v while the car is connected
whaaat? why, was it set up on a charging schedule or something?
Lol when I get out of my car I park in the garage and plug it in. It stays plugged in till I need to drive again. No charging schedules since they shut down the 3G networks because reasons
The battery that does the driving is completely different from the battery that does the rest of the stuff in the car. So whilst it sounds funny, it’s actually correct.
This is not a unique Tesla thing BTW, I think all electric cars work like that. The battery that does the driving has very different requirements, so keeping them separated is the best solution.
What is pretty shit from Tesla is the regular battery dying all the time. That’s a pretty unique Tesla issue.
The original telsa roadster used the main battery for everything, but it was proven a bad idea because any faults in the battery would leave the car completely dead with no lights or anything. Having a second reliable battery is simply good saftey redundancy.