Interestingly, this setup actually is quite efficient. You don’t have all the mechanical and thermal losses from alternator-charging, for example. Furthermore, lead-acid batteries have a lot of really desirable properties in an automotive environment. They’re capable of extremely high current delivery, are basically immune to noise and reverse current conditions, never lose capacity, can be revived from stone dead, work great at all temperatures, etc. Basically the opposite of Lithium chemistries, which are unbelievably fragile and finicky about everything. Automotive components are all designed around the properties of lead-acid cells, so if you don’t have such a battery in the loop, you have to create protections for all those conditions with circuitry on the Li-Ion pack. That means a lot of giant diodes, inductors, MOSFETs, etc to compensate for the harsh conditions of a car electrical system. The lead-acid cell acts like a buffer. ICE cars work similarly- the car is running off the battery, which is continually charged by the alternator, because it’s hard to get alternators to make nice power. Lead acid cells are bulletproof and act as a great regulator and buffer.
Wait… what? You sure?
ICE cars need the lead acid battery’s storage capacity and ability to dump huge current in order to turn the starter motor, though. You don’t really need any of those properties to run a bunch of computers and some LED lights, especially since you’re going to need a 12V regulated supply from the li-ion pack either way (lead-acid battery or no).
If not for the starter motor, I don’t think a modern ICE car would really have a need for a 12V battery either - while the engine’s running the alternator should be more than capable of powering the electronics, no?
Within reason, yah. They lose water and need to be topped up as they age, and eventually they do wear out, but it’s effectively forever compared to all other battery types. There’s no memory effects or cycle limits like other chemistries have, and over-discharging isn’t fatal like it is for most other types.
The 12V battery is used in my Fiat 500e to drive the system that controls the high-voltage system. There was a recent recall because the high-voltage batteries would be used to top up the 12V battery, which is fine unless the battery has gone bad. If that’s the case, it would use all of the large batteries trying to charge and would deep discharge them.
My Fiesta’s USB port is useless for anything more than maintaining charge, so I have a high-output dual plug-in for the front lighter port. The only problem is that the car is so random about powering everything down*, and I’m not sure what the adapter draws in standby (other than the LED), so I unplug it when I’m not using it. (I assume that a good buck-convertor would only draw power as needed, but…)
* it has a failure mode where if you open the rear hatch and then close it without extra-locking it with the key, it will keep interior lights on and drain the battery overnight. Fun when camping.
I like the cig lighter because it can drive an inverter with standard 110v sockets, and I can plug pretty much anything–phone or laptop charger, vacuum, the pump for my air mattress, microwave*–into those.
- Ok, probably not a microwave
If you want the fastest charging for Apple devices you need a 110v oem Apple charger. For that reason I recently installed an inverter with Apple wall wart in the dash.
I very much want to disagree with you, but when even my solar powered chicken coop features a USB-A interface…
Yah, the starter is definitely the biggest single current dump. However, the availability of that current has driven the design of all other automotive accessories over the years. Window motors and wiper motors, for example, are hugely powerful, as are headlights (which are mostly still not LED). Run all those at once, along with seat heaters, the 400W subwoofer that was a premium option, and that stuff starts to add up. Devices run on Lithium are extremely optimized to sip power. Nobody has ever bothered to do that in cars, and the current crop of available parts for electric car builders reflects that.
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