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Up in the Mountains in a Canyon, What to do for Power for a Laptop?

Yeti Goal Zero 400 Battery Pack and Charger
(recharges with AC, car charger or solar panel)

UPDATE JULY 2016: the Goal Zero / Yeti products look perfect for field needs. See Powering and Recharging Cameras and Laptops and Electronics in the Outdoors.


The smoky conditions were discouraging for photography (and cycling e.g., lungs), and led me to find a table and chair in a remote not-yet-trashed cabin to make use of my time in order to prepare Canon 5DS R vs Canon 5D S: Moiré and Aperture and Canon 5DS R: Noise Under Real-World Conditions in the Field. No problem in general, but it took 4-5 hours to prepare both pieces (evaluate carefully, write it up, etc, not so easy on a MacBook Pro vs home setup).

But what about when the MacBook Pro Retina has enough juice for about 3 hours of real-world usage (about 1/3 of the Apple battery life claims)? Walk a short distance back to the SUV, plug the Apple MagSafe brick into the 12VDC to 120AC power inverter, try to work in hot sunlit car with glare on the screen, idle the engine so that the SUV won’t get irritable about a constant power drain from a 85W Apple AC power brick plugged into a 12V DC to AC power inverter. Lotsa power sucked when battery is down to ~5% for a good while, low efficiency charging.

Which got me to thinking... the Sanho HyperJuice 1.5 External Battery with Magic Box Kit (222Wh, Silver) looks slick for just such a scenario. But I don’t have one and B&H won’t ship it apparently. [Amazon apparently will ship the Sanho Hyperjuice @AMAZON]. I’m wondering about it or some alternative out there. I’ve asked the manufacturer to send me one for review, but I don’t know how they’ll respond.

Apple has a MagSafe patent, but does not see fit to provide any 12V DC charging option for it. One can web search for MagSafe and see various products that skirt the edges of legality*. One source tells me that even modifying the MagSafe charger may be of dubious legality (I’m no legal expert, so I cannot say). The Sanho unit is of that genre; you modify the MagSafe power brick. If Apple would offer a solution to charging a laptop in a car... well patents are a Good Thing but can also ensure no solutions to real challenges, e.g., can be anti-customer.

Maybe USB-C will make all this charging nonsense vaporize (not sure).

* The end user customer has the right to modify the cable/charger, the issue is a another party actively enabling the conversion, which is risky under patent law in US. Sanho’s business is batteries, and they’re apparently willing to take the risk, but don’t look for their products in the Apple Store; Apple has many levers short of suing. What’s puzzling is that Apple has not pressured B&H to drop the Sanho product entirely, since B&H is an authorized Apple dealer, quite a lever indeed.

Sanho HyperJuice 1.5 External Battery with Magic Box Kit (222Wh, Silver)

Reader comments

Reader comments follow, in rough order received so as to not repeat/redo my comments.

Paul W writes:

I use several different strobe setups for photography---among them the Paul C. Buff Einstein strobes. Paul C. Buff has several options for portable power, including the Vagabond Mini. It comes with an AC charger, but there is an optional car charger available, plus extra batteries.

It might not be as small and sexy as the Sanho unit, but it is about half the price, and I am guessing it holds more juice (just a guess). On number of occasions I have tossed one of my Vagabond Mini units into the Jeep when I know I will need the spare power for my Macbook Pro, iPad or iPhone (or anything that requires power/charging and a low-amp draw). It also has USB ports in addition to the AC outlets.

DIGLLOYD: Vagabond Mini has 130 watt hours compared to 222 watt hours for the Sanho unit mentioned, one useless 0.5A USB port (even an iPad needs around 2 amps, external bus powered drives need 1 amp or so, so 0.5A is a toy), it's awkward and then there is the battery to 120V AC socket to MagSafe to DC efficiency losses.

If you're doing battery to 120V AC to MagSafe it's not efficient. Things will get hot and the power draw is pretty intense for a good period of time coming off a drained laptop battery. A MacBook Pro Retina has an 85W power adapter; this is a very high power draw on a lithium ion battery, not to mention the DC-AC-DC losses (battery to AC outlet on the unit to Magsafe to laptop). Power draw drops considerably when the laptop is mostly charged, so one would then have to cobble together things while working to have it feed in power to avoid discharge of the laptop battery to begin with. Oh joy. No, I want a high efficiency recharge unit so I can drain the laptop and then and only then cable in the external battery. The MacBook Pro Retina has a ~100 watt hour battery, so a 130 watt-hour external unit is not likely to even be able to charge it fully once DC-AC-DC losses are accounted for. In other words, the MagSafe technology needs a direct-12V-DC option, not just the AC power brick.

I can just go to an auto parts store and get a lead-acid jump starter box with cigarette lighter socket for $39 if I want a cheap DC source. I already have one, and maybe I’ll just sigh and do that. If it’s 50% efficient... well it also has an air compressor and can jump start a car and has a handle for carrying.

The issue is getting DC to DC efficiently (90% or more) and that Sanho unit does that by splicing into MagSafe to avoid the DC battery to 120V AC to DC cycle (skanky but I admire the ingenuity). Apple doesn’t care about outer-zone use cases like this, as usual with all its products.

BTW, kudos to the one and only one camera company I know of that does charging right: Leica supplies a charger with both a 120V AC and a 12V cigarette lighter socket charger that is supremely efficient for charging batteries for the M240 and other M bodies in a vehicle (12V socket). All camera vendors and laptop vendors ought to offer such a 12V charger.

Thom Hogan of writes:

My assistant and I have used the HyperJuice in Africa for years now, dating back to before Apple forced them to do that weird thing because of the MagSafe. We charge the HyperJuices off the vehicles as we travel during the day, then run them down while back at camp. They work great, and do pretty much what they say they do. Never had a problem with them (I’m still using my original, my assistant updated his to the latest). Indeed, they’re useful for quick charges of USB devices, too. The one thing I’ve not been able to do reliably with the HyperJuice is charge it from solar panels.

Even though we bring a generator on our workshops, I’d say we tend to do more laptop charging from the HyperJuice than the generator. First, the generator is a pain, noisy, and has issues with varying loads so we have to manage it very carefully. But second, the HyperJuice is just more convenient, as the vehicles we use all have multiple access points to charge it.

DIGLLOYD: reader Jeffrey J informs me that they are right over in Fremont, CA, across the bay from me (about an hour drive), so I may just stop there on the way out on my next trip. Also this table of battery life is useful.

Ross J writes:

Pawtec car charger for Magsafe

I found this Pawtec Macbook High-Speed Car Charger - Compatible MagSafe 2 for Apple Macbook / Air / Retina Mid-2012 - Present. I haven’t used it, but it might be an answer, and is a huge amount cheaper than the external battery.

DIGLLOYD: This looks perfect: 12V DC-in from car charger direct to Magsafe port.

How Pawtec can do this, apparently in outright patent violation and right in Westlake Village, CA (though that’s a suite and no phone numbe ris listed), I don’t understand, but I’ve submitted a question to them on that via their web form.

I’ve also submitted a form at Apple Legal regarding this Pawtek product. I don’t want to use products that violate intellectual property rights (MagSafe patent), so I figured that if Apple responds to me then I can proceed (or not) accordingly to try the Pawtek and/or HyperJuice products. If no reply, then dunno.

Update 06 July: Apple Legal has not responded, nor has Pawtek.

Other companies

BatteryBox in Mountain View CA, within spitting distance (so to speak) of Apple HQ, speaks to the patent issue explicitly in A special connector compatible with MacBooks:

Why a new connector design? The magnetic cable Apple designed for powering the MacBook is patented - only they have the right to use it. The SnapFit Connector is a solution that does not infringe on any intellectual propery, and allows for an easy method of connecting to the laptop.

The BatteryBox unit is 60Wh, which is about 27% of the HyperJuice unit, but BatteryBox is much smaller (A MacBook Pro Retina has a ~100 Wh internal battery, so 60 Wh is not a huge gain in runtime). A headache is that it cannot be charged by DC; it takes USB charging via an AC wall-wart, so back to the same old power inverter problem in the field.

BatteryBox with MagSafe compatible connector


With so many products skirting the edges, I wonder how Apple weighs in on this.

None of this mattered for 3000 years or so to this bristlecone. And still doesn’t.

f2.8 @ 1/200 sec, ISO 100; 2015-06-23 19:03:01
Canon EOS 5DS R + Zeiss 25mm f/2.8 Distagon @ 35mm

[low-res image for bot]

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