solora/hardware/power.md

BATTERY

• 1S LiIon/LiPo (3.7 V nominal)
• 18650 for easy ubiquitous availability (~3,000 mAh each)
• connect cells in parallel until we get the capacity we want
• lipo can charge at 1C

CELLS

INR18650-35E

POWER BOARD

Adafruit 6091

• $7
• 5-18V input, USB-C or PV/DC
• CC at 1.0 A, 0.5 A, or 0.25 A
• handles LiPo/LiIon or LiFePo cells
• optional thermistor to reduce charge current when battery overheats
• battery under voltage protection disconnects the battery from the load at 3 V
• schematic

Max charge rate is 1 A at 3.7 V nominal battery voltage, which is 3.7 W.

PHOTOVOLTAIC PANEL

Anything 5-18 V should be fine, the charger can't use more than 3.7 W.

Trying this one: https://www.amazon.com/Soshine-6w-Performance-Monocrystalline-Cellphone/dp/B09ZL3F7CT?th=1

ALTERNATIVE POWER BOARDS

CHARGERS

1. 5V 2A USB-C
2. 5V 2A
   • have on hand (i think)
3. Adjustable
   • combine with heatsink

strawman: charging up to 4v with the INR18650 (see CELLS:INR18650-35E for the discharge capacity graph, and CHARGERS:3 for 4V cutoff w/ a 5V panel) gives us ~3000mAh, or 88% of the 3398mAh tested battery life.

BMS

2. 3S 60A

SOLAR

• mppt charge controllers:

1. https://www.amazon.com/Waveshare-Solar-Power-Manager-Regulated/dp/B0CT2ZBML9
2. https://www.amazon.com/4-4-6-5V-Lithium-Battery-Charger-Controller/dp/B08DY28BXW