Anyone strip down a portable charger?

I haven’t tried, but I think you may be on to something.  All the plastic you look at from the outside isn’t strictly needed as it isn’t battery or circuitry.  And in all products I know of doesn’t even make it a waterproof package.  You could secure the circuitry, connections and cover any terminals with good tape and have a lighter, more compact package.  I’d use a little 1/16″ closed-cell foam that I save from packing materials to wrap and cushion any circuit boards before securing them to the main battery.

An interesting question…what percentage of total weight are you imagining could be saved?

Maybe I’m just easily frightened, but I’d be scared of setting that thing on fire!

>”but I’d be scared of setting that thing on fire!”

Yeah, but unlike in a jetliner, if the lithium battery shorts and catches on fire, you can just shrug your pack off.

I’ll see if I can strip one down and get a percentage saved.

Well, that took about 4 minutes in the garage.  I had a battery for a USB / 120-VAC outlet pack and I took the two halves of the case off.

In factory packaging: 798 grams

(lighter) bottom half of case: 78 grams

top half of case that secured the batteries and terminals: 110 grams

Expected weight of some bubble-wrap or 1/16″ foam and tape to secure/insulate the bits: 40 grams.

Weight savings (78+110-40)/798 = 148/798 = 19%

Note, the first half of the case was super easy to compensate for.  one strip of tape would have secured everything and saved 9% of the weight.

Also, this seemed to have a higher percentage battery weight than a lot of these after-market stand-by chargers. I suspect a lot of chargers could save 30-40% of their weight by stripping the case off.

I’d go the other way and buy mostly completed components.

Eg:

https://www.adafruit.com/products/1903 (3 grams) + batteries = MYOG portable charger.

The advantage I see there is the parts and specs of the circuitry component are better documented – in this case you get an idea of the efficiency you can expect. With the above linked item, you could run off anything >1.8V.  The component that does most of the work on that board – http://www.ti.com/product/tps61090 – accepts input voltages between 1.8V and 5.5V.
(Naturally a board using a TPS61090 may impose additional limitations/inefficiencies, one would have to look closely at the board. It could just be a reference implementation which the datasheet is based off, or it might not be.)

Why might you be interested in what voltages you can feed into the input? Because if you need a lot of power for a long trip, it might be a whole lot cheaper to buy a pile non-rechargable D cells, or lantern batteries.

Another board for a bit more money is https://www.adafruit.com/products/2465

my Anker 10,000 weighs 7.85 oz

an Anker 6700 costs $20 at Amazon, must weigh a little less

adafruit – 1903 is 1/10 oz $10, 6600 battery is spec’d at 5 oz $30, so 5.1 oz total and $40

I don’t think that’s going to end up saving any weight and it’ll cost 2X

thanks a lot, now I’m going to waste a bunch of time looking at all the cool toys at adafruit : )