Minimal Power Bank?

[Alex G]

I am using a power bank just to recharge my garmin watch on short trips (2-4 nights). My current battery pack is the smallest I could find and still weighs in at 4 ounces.

Has anyone found something smaller and lighter?

[Kevin Babione]

If you’re only using it for a watch you can go pretty small with the battery.  Search Amazon for “battery lipstick 3350” and you’ll that Luxtude has some at 2.45 ounces.  For roughly another ounce you can get one with a flashlight…

[JCH]

A lot of cheap, light, lower capacity power banks are given away as swag at conferences etc.  You may be able to score one (some) free.  Ask you co-workers?

I’d be surprised if most (all?) of these small cheap PBs were terribly high quality simply because the economics wouldn’t make much sense for the manufacturer.

[Brad W]

I think most Garmin watches have about 500mah batteries. So you need at least 3,000mah. I would look at Nitecore NB5000. There are lighter options but I would bet you need low voltage mode to stop the bank from shutting off as the watches draw too little amperage-most banks will power down in this scenario.

[bradmacmt]

Get an analog watch :)

 

[Dan]

I have a 3350 mAh lipstick charger (Anker Powercore+ Mini) that is 2.8oz. Of course, you still need to carry a short cable as well.

[Kevin Babione]

I figure the OP was carrying a cable already.  I did hike with a buddy who shortened a 3-foot cable to 8 inches to save some weight.  At the time a 3-footer was the shortest available.

[Rex Sanders]

I’m working on a BPL battery pack gear guide, which probably won’t be out for a few months. Currently focused on larger 10,000 and 20,000 mAh batteries, but here are tips based on my reading so far.

Look for a battery pack that supports “low power mode” or similar, to recharge small devices like watches. But you might waste a lot of energy letting low power mode continue running overnight after fully recharging your watch. Maybe recharge when you can conveniently shut the battery pack off after a couple of hours (set a timer). Batteries without low power mode might not recharge small devices that draw too little power.

If you find the battery pack you really want at a price you like, buy it now. I’ve seen too many desirable batteries suddenly go “out of stock” or “discontinued”, or prices double overnight for no apparent reason.

Amazon banned some well-known battery pack brands because they illegally paid for 5-star reviews. You can still find their products elsewhere.

Use short, thick, tough USB cables from reputable sources. And treat your cables with care. Lousy or abused cables can waste a lot of recharging energy.

— Rex

[Marcus]

Rex, have you seen this comparison? its highly useful for the raw #’s.

Hiking power banks comparison from Ultralight

Also I never considered the cable as a source of loss but it makes sense. Makes sense thicker and shorter cables are better to reduce resistance losses. Any particular cable you’ve found to be good quality?

I’m a big fan of the Nitecore 10k. Not light enough to fit the OP’s criteria, but does have low power mode and is the lightest 10k bank at the moment.

[Rex Sanders]

Marcus,

Thanks, hadn’t seen that.

I’ll test a much smaller selection of power banks, across a wider range of conditions important to backpackers, emphasizing a few parameters that actually matter. Haven’t started testing new power banks yet. Here’s a preview of some of my testing:
https://backpackinglight.com/simple-gear-tests-usb/

Planning on USB cable testing, no time frame yet. Others discovered that some cables waste a lot more energy than others – I was surprised. Hence these general recommendations until I can do more testing.

My goal is to describe tests that anyone can do at home with inexpensive gear. Especially with electronics, it’s almost impossible to keep a large list up to date. Even my short list of battery packs has been challenging, and I haven’t started testing yet!

— Rex

[Matthew S]

Poweradd 5000mAh lipstick style is 3.5oz iirc

[Brad W]

@Rex OP is more than likely using the OEM Garmin watch cable which is short and stout. I would never use a 3rd party cable for my Garmin watch-I have yet to see one that is near the quality of OEM.

Also, to hammer the low voltage point home-this may be needed. Watches generally draw 100mah or less-many banks will power off around this current. IME low power/current mode is a must. Unfortunately most smaller lipstick style banks don’t have this or published low current shut off thresholds-may have to try a few out. You need to watch the watch-it usually stops charging after 30-60 minutes if the watch is not drawing enough current for said bank.

 

This might be a good option. https://smile.amazon.com/Anker-PowerCore-Lipstick-Sized-Compatible-Smartphones/dp/B005X1Y7I2/ref=sr_1_3?dchild=1&keywords=anker%2Bpower%2Bbank%2B3350&qid=1632496855&sr=8-3&th=1

In the questions someone answered that 50mah is the low current threshold.

[NoCO-Jim]

Brad W: Did you mean mA instead of mAh?

[Rex Sanders]

In my limited fiddling, 50 milliamps (mA, not mAh), or roughly 1/4 watt, is the cut off for a few chargers and battery banks. Like you said, some keep running at low current for a little while, which might fool people into thinking small devices will completely recharge.

Low power cut off preserves battery bank energy, at the expense of the last few percent of recharging for larger devices like smartphones. But makes recharging small devices like smartwatches almost impossible.

That’s why many newer battery banks include a low power mode. Charge your smartwatch, but maybe waste too much energy if you let it run for too many hours. Probably no big deal for people in town; maybe a very big deal for backpackers. Tradeoffs worth testing.

OEM cables aren’t always the best. Others have found Apple-supplied cables are mediocre at best for energy loss. I’d like to find out for myself.

Rumors that future iPhones might drop wired charging in several years, inefficient wireless charging only. If that comes true, bad news for backpackers. We’ll see.

https://www.macworld.com/article/538706/no-apple-isnt-dumping-the-iphones-lightning-port.html

— Rex

[Brad W]

@NoCo Yes, sorry, 50mA.  FWIW, of the Anker banks I have used with my Garmin Instinct watch, they have not powered off until the watch was 100% charged, which was quite some time-very slow charging on that watch regardless of the power source.  The banks used did NOT have a low current mode.

[Mike W]

This charger uses an 18650 battery, so you can take an extra battery as needed.   I don’t have the weight handy.  I use mine with 3400 mah flat top (unprotected) cell.  The charger has built in charge protection.

https://m.fasttech.com/products/1421/10001919/1137904-miller-ml-102-universal-usb-smart-charger-version

[John S.]

I was checking out powerbanks wondering what the lightest is these days (18650 charger/powerbank)

and noticed that fasttech shut down late last year.

[Author]

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