Simple USB Charging 1W LED Light DIY

I Have A Thing For Li-Ion Batteries and LED's.

Saturday, 01 February 2020

I have gone through a lot of mobile phones, mostly given to me by my kids who always seem to want the latest and greatest phones. I myself have upgraded my phones but mostly to keep the Android Apps I use "relevent". Over the years I've accumulated phones, cables, chargers (I like re-using these as well), batteries, manuals, boxes etc. This post is specifically related the 3.7V Li-Ion batteries with inbuilt protection.

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This small DIY project is very basic, just a handful of extremely cheap ebay componants with minimal soldering, the 3 parts all mounted directly onto the battery using a glue gun.

  • repurposed mobile phone battery (Li-Ion 3.7V 350mA+) with built in protection
  • 1W LED with PC Board from ebay.
  • lithium battery charger board from ebay.
  • current limiting resistor 1 Ohm 1/4Watt (I didn't have any so I used 4x 22 Ohm in parallel = 5.5 Ohm). I just ordered 100x from ebay 1.2 Ohm resistors
  • a cheap switch from ebay
  • some hook-up wire

The soldering is basic and straight forward

  • battery charger board connects directly to the battery +ve to +ve, -ve to -ve
  • the 1W LED is made up like so, +ve -----[ Switch ]-----[ 1 Ohm Resistor ]-----( 1W LED )----- -ve, connected in parallel with either the battery charger board OR the battery.


  • glue the charger board, switch, LED onto the battery.
  • solder the resistor between the switch and LED
  • completed the connections using hook-up wire

For me, that is the end of this project. I made 10 of these, fully charged them up then stored then in a kitchen cupboard. On a 4 monthly schedule (sometimes I forget, even after 8 months) I pull them out, switch them on to see if they are OK, charge then stored onced again. I haven't had 1 failure yet.


Not looking too professional I did make an attempt of creating a somewhat pleasing housing. A plastic Mayonaise Jar (labels removed) with bubble wrap pushed inside and threw away the lid. This sits over the mobile phone battery. Looks neat at night!


Just a reminder for those not familiar with Li-Ion batteries. They do not last forever, from my research they can be recharged between 300-500 times. But considering they can be found in abundance or cheap to buy (brand new) this can still be a useful lighting system.

Earlier Lights made 4 Years Ago Still Working Fine

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