Hello Guys,
Beta test
I build the Low Power DigiPeater and tested it out. It is still running.
The goal was to build it with less parts and less costs as possible.
Some details:
-Controller Lilygo TTGO V2.1 / Heltec Wireless Stick / Heltec CT62 → around 20€
-Solar Panel (2.5W 5-6V) → 2-10€
-TP4056 → 0,1€
-1x 18650 3000mAh → recycled
-Antenna → diy build or 1€ on Ali
-Case → 2-10€
Total costs around 25-40€
Thx to Ricardo @CA2RXU we could managed to receive data without loosing a single package and still saving a lot of power.
I made a test with an Lilygo TTGO V2.1. The 18650 cell was still over 3.6V after 5 days of running the DigiPeater without a solar panel (it repeated every 5 minutes for 5 days).
If you consider to build one with an Heltec device the sleeping consumption is half of the Lilygo’s. So maybe you can use also a smaller solar panel. Depends how much activity is in your area.
A quick scematic. (don’t judge me)
Feel free to ask if u wanna know any details 
73
Julian