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Apple MacBook Pro: DC Power Input for Efficient Battery or Car Operation? (bypass DC-AC-DC waste)

Apple MacBook Pro computers now have USB-C, which has DC power input up to 100 watts.

It is inefficient to plug a DC-to-AC power inverter like the Wagan EL2601 Elite 400W Pro Pure Sine Inverter into a car cigarette lighter (maximum of 90% efficiency), then plug an Apple wall wart MNF82LL into the inverter (efficiency unspecified) so it can then convert that AC power back into DC for the MacBook Pro! One need only touch the inverter (high quality one for me) and feel how hot it gets, ditto for the wall wart—that heat is wasted power.

12V DC => 120V AC => ?V DC for charging the computer

I would guess that efficiency is at best 80% (meaning a 20% power loss), thus pulling more amperage than needed, which my SUV does not like for more than 10 minutes with a low laptop battery that causes the Apple wall wart to pull full power, probably something around 8 or 9 amps at 12 volts from the car battery.

A DC-DC converter could presumably run with about half the power waste.

So what I am wondering is whether there are any quality converters out there that plug into the cigarette lighter socket in a vehicle and supply ample USB-C charging power, thus bypassing the need for both a power inverter and the Apple wall wart. Such a 12V socket is found on every car, on jump starters, solar generators, the 434 Wh Anker PowerHouse 2, crowd-sourced NYA projects, etc. Particularly for solar generators (batteries charged by solar), the wasted power of a DC-AC-DC foobar loop is a BFD.

Of course what I want as perhaps even more is direct modest-cost USB-C charger battery support for at least 40 watts in a compact portable form factor. There are (claimed and I’m skeptical) solutions as of mid 2017 (Hyperjuice and MAXOAK), but not elegant ones, and I want them to be capable of solar charging like the Anker battery/solar panel combo.

Solutions

There are a bunch of USB-C car chargers on Amazon, but most are phone and iPad oriented (low power output). I’m dubious that any of them can supply 90 watts or even 30 watts charging power to a MacBook Pro (or whether they work at all), and one should be very careful with a cut-rate products—the amperage required is a serious draw.

BatPower CPD 110W PD USB-C Car Charger
for MacBook Pro

The BatPower CPD 110W PD USB-C Car Charger for MacBook Pro works well so far in testing and is nicely built and packaged with required cables. The BatPower ProE 36000mAh EX9 Portable External Battery Charger Power Bank looks interesting in that it seems to be able to power a MacBook Pro via USB-C, but it does require AC power to recharge the battery.

Anker makes some good stuff and there is the Anker Quick Charge 3.0 & USB Type-C 54W 4-Port USB Car Charger, but it claims 54 watts max and I wonder how it holds up to that kind of steady draw. And it might not even work at all since its power rating is under-spec'd and there is a charging protocol involved and the MacBook Pro might refuse to talk to it.

Reader Matt L points out the MCT USB-C Adapter Charger for Car & External Batteries, which is rated at 60W + 13W power output. I’ve asked for a review unit and will report on it if I receive one but I will say this: many a product that plugs into the cig lighter socket has connectivity problems—I don’ trust anything until it actually works (and doesn’t overheat). The blurrry camera-phone product shot on a dirty desk does not inspire confidence (I cleaned it up as best I could), but it is a small company apparently and perhaps they are electromagnetically talented.

MCT USB-C Adapter Charger for Car & External Batteries

You can charge your new Macbook Pro 15" from your Car at FULL Speed! Not to be mistaken for other lower powered USB-C Car chargers. This will charge your Macbook Pro without draining your internal batteries while you work on intensive applications!
Includes Standard USB port so you can charge both your Retina Macbook Pro 15" and iPad at the same time!

  • World’s First True High Powered Car and External Battery USB-C & USB-A QC3.0 charger adapter.
  • Connects to most high powered external battery banks.
  • Charges USB-C devices like Macbook, Macbook Pro, HP, Dell faster then anything on the market.
  • QC3.0 USB-A to fast charge your other devices at same time.
  • Wide input power range: 12-24vdc.
  • Includes cigarette cable and external battery cable connector.
  • Built in Safely and overload protection.
  • Compatible with all USB-C devices like Macbook 12”, Macbook Pro 13”, Macbook Pro 15”, HP, Dell, Google, and also smaller devices like USB-C cell phones.
  • USB-C cable not included.

Specs: 60w+18w (Total 78w)

  • Input: 12-24v, max 10A
  • Output:
  • 60w USB-C: PD 5v3a, 12v3a, 15v2.4a, 20v3a.
  • 18w USB-A: 3.6-5.5v,3a, 6.5-9v/2a, & 9-12v/1.5a.
  • Cigarette cable for car.
  • 5.5x2.5 to 5.5x2.5mm cable for external batteries.
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