Budget 270 mAh Solar Li-ion charger

This minimalist charger has decent capability despite his cost, $ 9.
Today in a cloudy winter day was able to complete the charge of a depleted two cheap10440 in parallel , around 600 mAh of capacity in a bit more of two hours.




The pictures are self explanatory , the links below…



The sense resistance of the charger board was changed from 1,2 kohm to 4,7 kohm

That looks like the same charging circuit that DX is selling. The TP4056 looks to be a true CC/CV protocol chip. I like the idea of running it off solar panels as well. I see they have a 10 pack of the cells, wire them in parallel and it should be able to support the full 1 amp charging current for 18650/26650 cells

Thanks for sharing your project! Green charging for the win.

Two more panels in the way . That guy have the best price by much , half or less than others sellers.

I’m planing put those two in parallel and with a switch or socket get 10V 300 mA or 5V 600 ma .

Then with the buck board pictured below ( amazing board to play with) make the arrange capable of others chemistry , like two , three or four Ni-mh in series



Now that’s an interesting little board that looks like it might work for my little project.

I’ve been looking for something to hook up to 2 bottle dynamos so that I can charge a battery pack through a usb port.


I have one of these on the way on the slow boat. plus 2 pannels.

I already have the ML-102 charger (USB) but for the price and the fiddle it looks like a bit of fun.

I am interested to know, will a 18650/26650 not be able to charge off 300ma due to resistance or is it just slow to charge due to the capacity and you only get so many hours of good light a day?

The resistance of a standard Lithium cell should be very low (cells with a high internal resistance are at the end of their life), so the only factor is time. With 300 mA you should be able to charge an average 18650 cell with around 2000 mAh in about 7 hours, given full exposure to sun. Australia is supposed to be a bit sunnier than Germany, so I think you should be fine :slight_smile:

Thankyou, That was my view (resistance not a big issue) . I already have a solar setup which is 12v 2+amps output, I thought building this would be a small but slow charger & if I want to speed things up I’ll add additional panels.

Looking forward to more sun this summer.

@ arenat: why did you remove the usb plug from your charger board? leaving it in there would make it much more useful, even if a bit redundant. :) your post made me go look for the panels, and I found these 3 deals, possibly the lowest prices around:

http://www.ebay.com/itm/251125528409 $6 40 pieces of 78x19mm @ 0.5v 0.5A each,
http://www.ebay.com/itm/350587792336 $12 4pcs solar panels 5v 150mAh each with Schottky Diodes
ebay 140826274091 or 251090225050
$2 USB-in to 4.2v Li-ion tp4056 charger,
http://www.ebay.com/itm/330699360087 $2 3v-to-5v step-up converter with USB-out, (prices fluctuate from $1.75-$4)
http://www.ebay.com/itm/150761684468 $3 10 jumper wires with 20 alligator clips.

edit: don't get the 40 piece bare panels, too much work needed. I ordered the 4x 5v pre-assembled panels instead. Slap one usb-in tp4056 board and one usb-out step-up converter on a 18650 case, and you've got yourself a custom living breathing ML-102. :)

AAx3, the USB port was removed because I want to keep it flat as possible to fit a notebook type holder , all four panels folded.

Regarding the price of cells you link I think it is too much work to make a neat panel from those. Not easy also . However if you want to learn go for it.

The alligators clips are good for my needs , currently I’m into headlights and because some of the host are very cheap going the glue route was necessary , https://budgetlightforum.com/t/-/1528#node-1659, in the pics below the ‘charger ports’ are visible.



The tiny black has a 750 mAh nano-tech from Hobby king , the another with the aluminium heat sink currently has an old 2P holder with two cheap ‘1600’ mAh from Ebay , actually 1000 total 500 each… now one has a Nichia 219 diode 3 mode 700 , 200 , 35 ma and the bigger one warm XML-T2 3 modes also , 1,4A in high .

Arenat, that's awesome...I want to try making one now!

Ahhh, this “budget” forum is no good for my wallet…. :slight_smile:

Sounded like a fun project, so now i´ve got 4 chargers, a pack of cables and a 5-pack of solarpanels on a slowboat from China…. :smiley:

Now I just have to stay away from buying a Skyray King, I def don´t need one, but it looks so nice….

But I also want a SF L2T, a fw clicky for my L2M and a Shadow BL-21 for my bike…… decisions, decisions… :stuck_out_tongue:

Can someone please explane why my posts were removed?……. i thought i was being helpful by replying to a forum member and providing links to a VERY affordable Cree flashlight and accessories (bicycle mount, 18650 adapter tube).

If you would like to see them for yourself, please PM me and i’ll happily send you the links.

It is because people (myself included) assumed you were a spammer as your were posting multiple times in your first post linking to one website.

fair comment…. lesson learned, thanks.

Welcome to the gang, zapper!

Thanks Raccoon City, hell of a welcome! the only way is up from here i guess.

Just for information guys…… those cheap solar 3-led torches have some useful parts, small glass solar panel, rechargeable li-ion button cells (2x 2016 or 1x 2032) and of course the 3 white led’s and momentary push button.

I bought a batch of 10 some time back and have made a USB travel charger/light with the panels…. (hint) try not to get the solder contact on the panel too hot, the contact pad will fail/fall off…… use wire glue instead for best results, and dont forget to include a small signal diode in your circuit (small signal or schottky diodes have less voltage drop than normal diodes).

Pulled these from my watch list, i do most of my shopping from ebay.com (because it’s cheaper than ebay.co.uk)

Type this number into your ebay search bar 150761684468 it’s 10 croc clip cables for $3.

If you’re in the UK something like this 271003775040 it’s 11 Dell batteries for £13.95 but i contacted them directly and got something similar for £12 (various laptop batteries, worked out at £0.16 per 18650 cell).
Dell C/series batteries each contain 8x 18650 cells, the faulty ones usually have 2 dead cells, the rest are good and rated at about 2200mAh each although you will often extract them in matched pairs which doubles they’re capacity.

If it’s solar cells you need, a set of 5x 8v 100mAh for $13.98 190712221810
The charger boards you guys are using are good for up to 8v and down to 4.5v, these cells in parallel will give you 500mAh and the wider voltage means it will still work even in low light conditions, run them through a diode (as previous post above) make sure you swap the small resistor on the charger board to get the maximum charge current to your batteries if you’re using a powerful battery bank (or anything bigger than the average phone battery >1500mAh).

used phone batteries are a good source for protection circuits, these are needed in ANY lithuim circuit so that the cell doesn’t over-discharge and becoming a paper weight, the raw cells in a laptop battery don’t have protection……

Any questions or if you need pointing in the right direction…… just ask. :slight_smile:

i feel i should mention to be extra careful extracting lithium cells from laptop batteries, the cases are sometimes quite hard to crack open and shorting or puncturing the cells with a metal pry tool or screwdriver could be disastrous or even fatal.


if the battery: sparks, smells funny, starts hissing, gets hot…… throw it outside away from flamable items and leave it…. come back to it MUCH later when any danger has passed…… a lithuim battery fire is toxic, they can and often do explode when mis-handled…… please search for youtube clips and decide for yourself if the risk is worth it!