Nice chart for backpacking device power consumption

What are the headings for the columns, or at least the heading for the last column, I’m not sure I understand what they’re saying in that last column.

I often double-check technical information published in Backpacker because I’ve found too many hiccups in the past. The pattern continues.

The third column in that chart seems to be an example of energy use / recharging patterns, not any kind of “average.” The author even states up front: “Consider how often your devices run out of juice with normal use.” The article doesn’t make that very clear for the chart.

I spot checked a few of the Wh (watt-hour) numbers in the chart against manufacturer specs and found some discrepancies. The article claims that most small batteries run at 3.7-3.8 volts, then goes on to use 3.6 volts across many devices. Bad assumption.

The Sony camera battery at full charge supplies 8.4 volts, which translates to 8.6 Wh stored – about 18% more than the 7.3 Wh shown, which seems to be based on 7.2 volts.

And all batteries require more energy to recharge than they store, due to inefficiencies like resistance in the wires and battery during charging. This lost energy varies from device to device.

For example, the Petzl headlamp battery needs 7.5 Wh (vs 4.5 Wh in the chart) to recharge via USB.

And the article recommends solar panels if a battery bank is insufficient. But many PCT thru-hikers mail solar panels home early in their trip. Most rely on battery banks with 37 Wh (“10,000 mAh”) to 74 Wh (“20,000 mAh”) of capacity and recharge those in town. Solar panels probably work best in base camps.

Yet the story describes a pretty good process for estimating battery recharge needs while hiking. Just confirm the numbers before you rely on them – preferably with actual measurements.

— Rex

@rex

wow. Thank you. That’s really unfortunate that a chart can be published and yet be that far off. I wouldn’t have even thought to need to vet the data.

There is something quite charming about this thread running concurrently with the thread about technology ruining the wilderness experience…grin

Yeah, it also coincides with my post for “Old Timers” on items we carry now that we did not carry ‘back in the day’ – like ’60s through the ’80s.

Lots of “really keen” tech stuff we now carry. But hey, I’m grateful for my SPOT beacon. It’s insurance whenI hike and hunt solo.

Third column may be expected use per day (so charge needed per day).

https://www.backpacker.com/gear/how-to-power-your-electronic-devices-in-the-backcountry

see Rex already said same thing.

I gotta say, your phone should be in airplane mode while backpacking, and thus, use way less than 50% battery per day.

Last column, for example “charge 50% every day”, for 3110 mah device would require 1555 mah per day.

The only problem with this approach is it assumes I can figure what the percent charge required.  Especially a phone can be variable.

Another approach would be to start out with a 10,000 mah battery and try it on a number of trips.  If I frequently get close to using all the battery, then get a bigger one.  If I never use even half the battery, get a smaller one.

I originally got a 10,000, then a 20,000, finally a 13,000 which is what i now use.  I keep the others in the car.  I often camp at the car so I can make sure and start backpack with everything fully charged.  13,000 is enough to last 5 nights.

Yeah, put it in airplane mode.  Also, close all apps.  Normally, apps in the background dont use battery but sometimes they do.

I listen to podcasts with bluetooth earbuds.  That takes some more power.  If I’m running low on battery, I’ll turn that off.