Anyone else see EV manufacturers replacing 12V/low voltage lead acid batteries with lithium ones?

Discussion
41

@kwame
Yep, some EVs can charge the 12V from the main battery, but others can’t. If the 12V battery is dead, a booster just powers up the electronics long enough to activate the main battery’s contactors.

42

@Amelia
Seems like an override button for the contactors would be handy in case of a dead 12V. It’d be a bit inconvenient, but you could at least get the car going again.

43

kwame said:
@Amelia
Seems like an override button for the contactors would be handy in case of a dead 12V. It’d be a bit inconvenient, but you could at least get the car going again.

A lot of cars have the contactors inside the high-voltage battery compartment for safety, so they’re not easily accessible for an override.

44

kwame said:
@Amelia
Seems like an override button for the contactors would be handy in case of a dead 12V. It’d be a bit inconvenient, but you could at least get the car going again.

The Kia Niro PHEV has a manual button for that and a lithium-ion 12V battery.

45

kwame said:
@Amelia
Seems like an override button for the contactors would be handy in case of a dead 12V. It’d be a bit inconvenient, but you could at least get the car going again.

You’d also need a way to pre-charge the contactors. Just an override isn’t enough.

46

@kwame
The traction battery is disconnected when the car’s off, except when it’s charging the 12V. If that fails, the 12V goes flat and the car can’t connect to the main battery. The booster just gives it enough juice to wake up and start charging again.

47

unknown said:
@kwame
I thought that as soon as you turn the car on, the main battery starts charging the 12V, just like an alternator does for an ICE car.

That’s true, unless the 12V is in such bad shape that it can’t power the system to wake up the main battery.

48

@kwame
My Bolt and my wife’s Hyundai Ioniq 5 both came with lead-acid batteries. The Ioniq 5’s battery died after just 16 months, so I swapped it for an AGM.

49

@unknown
True, but lithium doesn’t need to be as big as lead-acid. It’s frustrating that the sizes haven’t changed.

50

@unknown
Couldn’t Tesla do the same by selling parts directly to customers?