[DisasterRadio] Look Ma, no batteries

[samuk at disroot.org]

Hi all

I had a play with the TTGO boards today, a good connection to at least 400m NLOS.

I was running them without batteries, I rigged up a capacitor and 3.7v charge circuit (In an
attempt to add some hysteresis.)

Pic here: https://archive.org/download/supercap/supercap.jpg

I used a cheap '15w' USB solar panel, which probably puts out 10w in reality.

Pic here: https://ia601508.us.archive.org/20/items/solar_201912/solar.jpg

I used this BMS ~£3
https://www.ebay.co.uk/itm/3-7V-Li-ion-BMS-PCM-Battery-Protection-board-PCM-for-18650-Lithium-Ion-UK
SHIP/123403495796?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

This capacitor ~£3
https://www.ebay.co.uk/sch/sis.html?_nkw=2Pcs+5.5+V+4.0F+Super+Capacitor+V-Type+Button+Smart+Capacit
nce+component+^TWUK&_id=113721196456&&_trksid=p2057872.m2749.l2658

The capacitor did help a bit with booting, but it was pretty marginal.

Interestingly this board does seem to boot from 15w solar via USB with no battery, or capacitor
connected (Usually they struggle)' This was with thin cloud cover.

A Voltage supervisor would probably improve it further: 
https://www.hackster.io/jonasvugt/esp8266-solar-moisture-sensor-with-supercapacitors-751865


Next time I have a bit of spare cash I'll get a ~£17 20w panel and try that out too
https://www.ebay.co.uk/itm/20W-Waterproof-Battery-Solar-Panel-12V-5V-DC-USB-Home-For-Phone-RV-Car-Ch
rger/163574101987?epid=24028930269&hash=item2615c6b7e3:g:m2wAAOSwxlxcejtP

You could then stick the device in something like this 
https://www.ebay.co.uk/itm/Waterproof-Junction-Box-Electrical-Cable-Connector-Outdoor-IP66-IP68-Unde
ground/133174724849?_trkparms=aid=1110001&algo=SPLICE.SIM&ao=1&asc=40732&meid=d10eca401a8342b7b4c7c5
39edb0796&pid=100005&rk=3&rkt=12&mehot=co&sd=323702807533&itm=133174724849&pmt=1&noa=1&pg=2047675&_t
ksid=p2047675.c100005.m1851

And attach that directly to the panel.

Thanks

Sam