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Reducing the weight of a solar charger

Hi fellow UL hikers, I want to show you my last project

Please forgive me for not using German language, I am following this forum for a while now and got plenty of useful info so I want to contribute something to this nice community as well. For now, using english is the only way that the text is readable for you:-D

I was looking for a decent and cheap light solar charger around 7-10W, so I narrowed my selection to a bunch of chinese brands with high efficiency Sunpower cells. At the moment of purchase, the cheapest for me (Ebay) was Allpowers 10W with final price about 40-45€. Original plan was to reduce weight only by removal of pocket area and changing heavy PVC coated fabric on the back side (arround 390GSM) with some lighter nylon. Once I put the thing apart I figured out that solar cell is laminated in a 3 layer material which can be pierced with domestic sewing machine, so a decision was made to change the front fabric as well and remove exccesive material from the panel.  Here is a short guide how I did it:

Original weight of the solar charger was 303g

 

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Ripped open the seams, panels are covered with 2mm bad quality open cell foam which I discarded

 

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I was suprised that cables connecting the two panels weren't isolated, they can touch each other if charger is opened beyond a certain angle. Fixed that - simply wrapped one cable with electrical tape.

 

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Usb connector chopped off, panels ready for seam ripper

 

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Original size of the panels - a lot of unnecessary material arround the cells  (corners arealready cut by me)

 

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All excessive material from panels was cut off, after looking at this photo I removed aditional ~1mm of material on each side and rounded down the sharp corners (forgot to take photo after, total 14.5g of plastic removed)

 

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At first I was thinking to use some 20D or 40D silnylon but it is not very scratch resistant and I was also bothered by transparency of the fabric. Perfect fabric would be something arround 70D as extex PU 90 GSM Zeltboden but I didn't have any so I went with 120GSM-ish ripstop With PU coating.

 

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After making a paper pattern, the eges were folded and »pinned« and then sewed. It would be much easier to use two sided fabric tape or iron the fold.

 

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Connecting the panels to the fabric. Used the same sewing clips to fixate the fabric onto panels but easier would be just to glue the fabric on and then sew trough. Since I didn't iron and glue the fold I tried to put stitches trough the same seam, to make more professional look , I succeeded on 2nd try (left side)J Machine was struggling a bit but did job okay.  Watch out not to sew trough the cables!

 

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Ok, the tricky part is done, now its time for the back side with big storage pocket, suitable for small 7-8 inch tablets as well. Outer material is the same as front, the thin 20D silnylon is used only inside the pocket. Closure velcro is salvaged from original fabric and cut in half so its only 1cm wide.

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Reinforcement patch for cable eyelet glued on with silicone on both sides, I was in a hurry and made square patch, better to make it round shape so it won't peel off easily.

 

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When pocket was finished, I just folded all side edges, attached some grossgrain ribbon tieouts and sew the front and back piece together. Also added kam snaps on the corners.

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213g, weight reduced by ~30%, I am more than happy with results :-) Now this is one of the lightest solar chargers in terms of weight/power ratio out there:-)

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Note for Super UL hikers :-) - I think up to 20g more could be removed:

  •          Female usb connector is extra heavy (arround 8g) I havent found good alternative to replace it, maybe i will solder micro usb cable directly to the charger...
  •      Using lighter fabric 70D, 40D, or even 20D
  •      Removing pocket and snap

If you have any comments or questions use any language you like. Ich habe 3 jahre in der schule deutsch gelernt deshalb Ich verstehe viel:-D

 

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Nice, detailed description...

Good idea...

You had thought about using Tyvek for the sleeve ?

I also think, it would make sense to change the connector against a bit longer cable with a male micro usb plug.
In this way it fit´s direct for powerbanks, smartfones etc and for units like Gopros, Pixo etc you need only an adapter female micro USB  to male mini USB...

You stripped also your powerbank ?
 

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Haha...cool!  The same i made at weekend! :D  I've a solar charger with three panels...without the original case the current weight is at about 400g..i've to remove the plastic sheets and whole fabrics as you done. One idea was to use only two panels and one for other stuff.  At time i'm planning my new backpack with build-in holder for the solar panel. With the panel i will build an small and light usb powerbank with water protected usb port outside into the backpack.

solar1.jpgsolar2.jpg

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vor 18 Stunden schrieb khyal:

You had thought about using Tyvek for the sleeve ?

I never worked with Tyvek so I don't know.

For power storage I haven't decided yet, I have 4 spare batteries for my smartphone. Thinking to make just a simple battery charger for spare batteries. This way I can charge phone batteries directly to avoid 10-15% power loss. 

TP4056 + Universal charger  When all unnecesary plastic will be removed I estimate total 14-17g for battery charger and 32.5g for each 1700mAh battery taken.

So if I take 3 spare batteries (total 5100 mAh, 115g) I am ok for 1 week of bad weather:-) 

IMG_20160518_143323.jpg

If This chip is used, you can also make a powerbank using your phone batteries. I would like this feature but don't know if I really need it :)

vor 5 Stunden schrieb AlphaRay:

  At time i'm planning my new backpack with build-in holder for the solar panel. With the panel i will build an small and light usb powerbank with water protected usb port outside into the backpack.

Looking forward to see it :) 

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