Using 18650 Batteries as a Lightweight Power Bank for Backpacking

As I talk about in my post about the best ultralight power banks for backpacking, one interesting solution is to bring 18650 batteries and use them as a power bank.   You just then need a charger which also has discharging capabilities so you can charge your phone and other USB devices with the 18650 batteries.  Here is how it works.

 

What Are 18650 Batteries?

Technically called cells and not batteries, 18650 batteries are rechargeable lithium-ion batteries.   They get their name because they measure 18mm x 65mm. Some newer 18650 batteries are actually a bit larger than this though.

Compared to standard rechargeable (NiMH-LSD) batteries, 18650 cells are much more power dense and thus lighter-weight. They also are also more efficient: in real-world situations, you are going to get more capacity with a 18650 than a NiMH-LSD battery.

 

18650 Batteries vs. Power Bank

Most power banks actually contain 18650 battery cells or other li-ion cells inside their casing. Thus, 18650 cells and power banks have a lot of similarities when it comes to performance.  However, there are some important differences when it comes to backpacking.

Here’s how the pros/cons break down.

 

Pros of 18650 Batteries for Backpacking

Modular Solution

This is by far the biggest benefit of using 18650 batteries backpacking.  The entire setup is very flexible. On weekend trips, you probably just need one 18650 cell.  On long thru-hikes or situations where you have high power needs, bring as many cells as you need.

 

Weight

Power banks have gotten incredibly lightweight.  The Anker Astro E1, for example, has 6,700mAh of power at 4.4oz – which is 1,522mAh per ounce.

But it is still hard to beat the weight of a 18650 cell for ultralight backpacking.

A NiteCore 18650 3,500mAh cell weighs approximately 1.8oz.  Their LC10 charger weighs just under 1 oz.  There are other chargers with discharging capabilities, but the LC10 is the lightest I’ve seen.

Here’s how the weight breaks down:

  • 1 cell + charger (3,500mAh )= 2.8oz = 1,250mAh per oz
  • 2 cells + charger (7,000mAh) = 4.6oz = 1,521mAh per oz
  • 3 cells + charger (10,500mAh) = 6.4oz = 1,640mAh per oz
  • 4 cells + charger (14,000mAh) = 8.2oz = 1,707mAh per oz
  • 5 cells + charger (17,500mAh) = 10oz = 1,750mAh per oz
  • 6 cells + charger (21,000mAh) =11.8oz = 1,779mAh per oz

True, you do have to add in the weight of cables and a carrying case for the 18650 setup.  However, you can use silicone sleeves for the cells (which weigh almost nothing) and you’d have to bring cables for a power bank too.

*Note that this definitely isn’t the lightest setup when it comes to mAh per oz.  The NiteCore NB1000 Ultra Slim has 10,000mAh and weighs just 5.5oz – which is 1,887mAh per ounce.  But that powerbank doesn’t have the same flexibility as using 18650 cells.

nitecore lc10 charger

Shown: The LC10 charger/power bank by Nitecore. The charger weighs just 1oz.

 

Cells Are Replaceable

All types of batteries – including 18650 cells and power banks – will eventually lose storage capacity over time. However, with 18650 cells, you have the ability to replace them as it happens. You can just bring a new 18650 battery on your trip.

This isn’t possible with power banks.  The cells are soldered inside the pack.  Unless you know how to hack the power bank, you won’t be able to easily remove the cells.

 

Device Compatibility

If you switch your lighting to 18650 cells, you will only have to worry about one type of battery.   Yes, you could use a power bank to charge a USB headlamp – but you lose power when converting between different types of batteries.  In this sense, using 18650 cells as your power bank and lighting battery is the most efficient solution.

 

Downsides of Using 18650 Batteries for Backpacking

Charging Time

The biggest downside of using 18650 cells when backpacking is the recharging time.  They generally can only be charged at 0.5 to 1 amp input. By comparison, most good power banks recharge at 2.4 amps.  They also recharge all the cells in the power bank at the same time.  Unless you have a multi-slot charger (which will weigh more), you will have to charge each 18650 cell individually.

You generally need 3 to 6 hours to recharge one 3,500mAh 18650 cell.  By comparison, the Anker 6,7000 power bank will recharge in 3 hours.

This isn’t really a big deal when going on weekend backpacking trips.  But it is big drawback for thru-hikers who will you waste a lot of time sitting next to wall chargers in town.  Keep in mind that it is often difficult to even find an available wall outlet on popular hiking trails.

 

Convenience

It is a lot easier to just bring a power bank with you when backpacking.  With 18650 cells, you’ll need to keep track of which cells are discharged, charging  times, and so forth.  There can also be a lot more parts with a 18650 setup, such as cables, cases and adapters.

 

Cost

18650 cells are pretty pricy.  Expect to pay $10 to $25 per cell depending on the capacity and features (some are high-performance, rated for cold-weather, etc.).  You’ll also need the charger, which is another $10-$30. By comparison, you can get an ultralight power bank for $20 to$60.

 

Learning Curve

The final drawback of 18650 batteries for backpacking is the learning curve.  It’s confusing as hell for newbies to figure out which type of 18650 cells to use, how to optimize the setup, how to daisy chain your flashlight and devices to charge them all at once…    It might not be worth researching all of this just to save an ounce or two from  your power setup.

 

Best 18650 Batteries and Charger/Power Banks

18650 batteries are expensive.  So, it’s no surprise that there are a lot of fake 18650 batteries out there.  These may work but have significantly reduced power capacity (you can tell because they will weigh less than real 18650 cells). Cheap 18650 cells also might not be protected and thus could spontaneously catch on fire (remember those Galaxy phones?).

The bottom line?  Don’t waste money on cheap knockoffs.   The same advice also applies to all types of batteries and power banks though.

Right now the best 18650 cells are made by NiteCore and Fenix. The 3,500mAh cells weigh approximately 1.76oz (50 grams).   Both brands make chargers with input/output, allowing them to work as power banks.

These are good 18650 chargers which also have output so they work as power banks:

  • Nitecore LC10 Charger: 28 grams (0.98oz), 1amp output, 0.5amp input, also on Amazon
  • Nitecore UI1 Charger: 40 grams (1.43oz), 800mA output, 1amp input, also on Amazon
  • Fenix ARE-DI Charger: 61 grams (2.15oz), 2amp output, 2amp input, has digital display screen, also on Amazon
  • Fenix ARE-X11: 41 grams (1.4oz),1-2amp output, 1amp input, has plastic case

Sources:
https://www.fenixlighting.com/blog/the-ultimate-guide-to-the-18650-battery/
https://backpackinglight.com/forums/topic/98746/
https://www.reddit.com/r/Ultralight/comments/8m589n/power_banks_are_heavy_and_i_hate_carrying_them/
https://backpackinglight.com/forums/topic/90896/
https://www.reddit.com/r/Ultralight/comments/816pwk/18650_ul_battery_pack_replacement_modular/
https://backpackinglight.com/forums/topic/battery-bank-for-charging-electronics/

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