I’ve been thinking about this, because I carry an ENB charger with 2 18650 rechargeable batteries.  For overnights it’s great, enough charge without extra weight. I have two questions,  though: is it better to top up electronics every night, or let them run down aways before recharging? And, (I’ll probably have to figure this out for myself) how many days of travel would it be before it makes better sense to bring a heavier battery pack vs. more 18650’s that are already charged? I believe the Anker battery pack I use for EDC is 10500, so at some point it might make better sense?

Chad: An Anker FAQ lists output efficiency at 60% to 70%, much worse than your 80% estimate.

Diane: Recharging efficiency gets worse as you get closer to 100% for most batteries. I would consider running devices down to around 20%, then recharging to 80%, for maximum efficiency. Unfortunately, that means you can’t plug in and forget during recharging.

ENB + 18650 batteries versus Anker battery – it’s about a wash. Four Panasonic 3400 mAh 18650 batteries plus an ENB two-battery charger weighs about 258 grams, and yields 50.3 Watt-hours, before efficiency losses. An Anker 10050 battery weighs 236 grams and yields 50.3 Watt-hours. But with the ENB, if you need a little more or less power, you just take a couple more or fewer 18650 batteries. Most sleek battery packs like the Anker have 18650s inside; and the electronics for charging/discharging is about the same, so not a big surprise.

Patrick: Yes, you can recharge the battery inside the Sony RX100 Mark VI via USB. Many cameras do that now.

— Rex

More on recharging:

Thru-hikers also value rapid recharging, not wanting to hang out in town waiting for battery packs to recharge, while competing with other hikers for limited outlets. But there’s a lot of confusing marketing around new quick-charging standards, so buyer beware.

Non-rechargeable lithium AA batteries pack more energy into less weight. Unfortunately, most USB chargers that use regular AA batteries are junk. If this tiny, 10 gram Ovtech charger is any good:

https://www.amazon.com/dp/B06XPWYD5Q/

… then replacing Diane’s Anker 10050 battery theoretically would take 14 Energizer Ultimate Lithium AA batteries and weigh a total of 184 grams – saving 52 grams (1.8 ounces). Plus you can carry more or fewer batteries depending on your needs. And these batteries work great at sub-freezing temperatures.

You can ship small quantities of lithium AA batteries for thru-hikes; be sure to follow the rules of your carrier.

Downside: disposable batteries versus rechargeable. TANSTAAFL, HYOH.

— Rex

good comments

USB chargers are rated at the capacity of the battery, which is 3.6 volts

This has to be converted to 5 volts for USB, so there’s an inefficiency of 3.6 / 5 = 72%.

10,000 mAh battery will yield 7200 mAh of USB voltage to charge devices

Plus, there is inefficiency added so it’s less than 7200 mAh

But, maybe the calculations are futile.  A lot of people use Anker 10,000 or that 2 18650 charger.  They seem to be fairly reliable.  Try that on a trip and get a bigger one for the next trip if you run out.

“Long Lens: 24-200mm (equivalent) lens. An incredible achievement for a camera that’s pocketable, has a mid-sized sensor, and only weighs 10.6 oz (I verified the weight – that includes the battery and SD card).”

The Panasonic Lumix ZS200 has a 1″ sensor, shoots 4K digital, RAW, has a 24-360mm lens, weighs just under 12 oz with battery and card, and only costs $800. Looks like a great little camera. The ZS100 that it replaces is even cheaper with most of the same specs, but only a 25-250 lens.

Battery temperature ranges is not something I’ve dug into. Energizer Ultimate Lithium batteries have an extraordinary range of good operating temperatures; most common batteries don’t, including rechargeable lithium-ion.

<steps up to soapbox>

For backpackers and other outdoor enthusiasts who play or work in a wide range of temperatures, rechargeable batteries suck when we have lighter, wider-temperature-range batteries available like the Energizer Ultimate Lithium. That goes for headlamps, flashlights, satellite communicators, watches, cell phones, tablets, cameras, twinkling tent lights, blenders, etc.

I’m astounded that people who sell electronics specifically for emergency outdoor use, like the Garmin inReach, use rechargeable batteries that are guaranteed to let you down when it gets a little too warm or cool. Note the original DeLorme inReach ran fine on off-the-shelf AA batteries.

We compound the problem by carrying another rechargeable lithium-ion battery to recharge the other stupid batteries. No wonder overnight recharging in the backcountry fails to meet our expectations!

Yep – there are a bunch of other tradeoffs. At least if most outdoor electronics ran on standard replaceable batteries, we’d have a choice between cheap alkalines, rechargeables with various chemistries, and high-performance non-rechargable lithium primary batteries. But we don’t, and that’s a shame.

Some designers have figured out how to include rechargeable wide-temperature range batteries, like the Yellowbrick YB3. Why can’t the others?

<steps down from soapbox>

— Rex

Most of my electronic devices I use in the backcountry would be significantly bulkier if they used replaceable lithium batteries. Worse, the waste and cost would be ridiculous. Most in the lightweight backpacking community don’t seem to care too much about cost to save weight, but some of us care about reducing waste.

Li-ion betteries do not really like the cold indeed.

I’ve bought a waist pack at my local market as an experiment. It is not ultralight but worn under outer layers it did the job of keeping my phone, camera and power bank batteries in good condition in near- and sub-freezing conditions. I found it more comfortable to wear diagonally like a sling bag rather than horizontally as it was intended.

Sucks to open up all the zippers every time to take a picture but the difference in battery longevity is worth it.