The Feather 1S blocks on a longer board with an 18650 holder. One or two cells in parallel, the thermistor pressed against the cell, and everything else identical: same pinout, same library, same Bluetooth.
Highlights
- 1S1P or 1S2P 18650 in an on-board holder; LiFePO4 or Li-ion
- Thermistor pad against the cell, so the charge window is the cell's
- 10 W from solar, 15 W from USB-C
- Months per charge at typical IoT duty cycles
Battery
| Cells | 1S, one or two 18650 in parallel |
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| Chemistries | Li-ion, LiHV, LiFePO4, LiSOCl2 primary mode |
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| Battery interface | On-board 18650 holder with NTC pad; 3-pin JST-PH also fitted |
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| Protection | Overcharge, overdischarge, overcurrent, short circuit, temperature; programmable per chemistry |
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| Fuel gauge | State of charge, voltage, current, temperature, time to empty; ±3 % on LiFePO4 after one cycle (measured) |
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Inputs
| USB-C | 5 V at 0.5, 1.5 or 3 A, read from the CC lines |
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| Solar | 6 to 22 V, MPPT, 10 W continuous, 15 W peak (measured) |
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| Charge current | 50 mA to 3 A in 10 mA steps; default 0.5 C |
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| Charger efficiency | 94 % peak, 91 % at 3 A (measured) |
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Outputs
| 3.3 V rail | 1.5 A continuous (measured) |
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| 5 V rail | 2 A continuous, switchable; off by default (measured) |
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| Signals | PG, CHG_DONE, INT, EN5V on jumpered Feather positions; VSYS and VBAT on pads |
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Supervisor
| Supervisor | nRF52840 module, Zephyr firmware, I2C at 0x36 |
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| Bluetooth LE | BTHome v2 broadcast, Battery Service, custom GATT; read-only by default |
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| Idle current | 28 µA outputs unloaded; 42 µA advertising every 2 s; 3 µA in ship mode (measured) |
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| Libraries | Arduino, C, MicroPython; one register map, v1.2 |
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Physical
| Outline | Feather-width, 75 × 23 mm, Feather header on one end, four mounting holes |
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| Board | 4-layer, ENIG, matte navy |
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| Operating temperature | −40 to 85 °C board |
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Feather header
| 3V | 3V3 · out · Regulated 3.3 V; drives the host's 3V position |
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| EN | EN (host) · out · Pulled low through a jumper closed by default, so the host's own regulator stays off |
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| BAT | — · — · Not connected, by design: the host's charger must never see the battery |
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| USB | — · — · Not connected, so two 5 V sources are never in parallel |
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| 11 | INT · out, open drain · Event interrupt; jumper open by default |
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| A2 | PG · out, open drain · Power good, both rails in regulation; jumper open by default |
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| A3 | CHG_DONE · out, open drain · Charge complete; jumper open by default |
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| A5 | EN5V · in, pulled up · Enable the 5 V rail; jumper open by default |
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| SDA, SCL | I2C · — · Qwiic bus at 3.3 V; the supervisor answers at 0x36 |
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| GND | GND · — · |
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| 5V | 2-position 3.5 mm screw terminal block and a pad · Rated 2 A; switched by EN5V and set5V() |
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| VSYS | Pad and castellation · Raw system rail, battery or input, whichever the power path selects |
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| VBAT | Pad and castellation · Battery terminal after the BMS switch; never the host's BAT position |
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| NTC | Battery connector pin 2 and a pad · 10 kΩ, B = 3435 by default; other B values are a setting |
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Physical
| Mass | 21 g |
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| HS code | 8504.40.95 |
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| Origin | Assembled in China; designed and tested in Canada |
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Compliance
- CAN ICES-003(B) / NMB-003(B)
- This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.
- Contains IC: 8017A-MDBT50Q
- Contains FCC ID: SH6MDBT50Q
- The radio module is exempt from RF exposure evaluation (RSS-102 Issue 6, FCC 47 CFR 2.1091) at any separation distance; keep the antenna area clear of metal.
- RoHS 2011/65/EU and (EU) 2015/863 compliant.
- REACH: contains no SVHC above 0.1 % w/w.
- Country of origin: Assembled in China; designed and tested in Canada.
- Export classification: EAR99. HS 8504.40.95.
No cell is supplied with this board. Set the chemistry jumper for the connected cell before the first charge. Safety: https://www.snowbirdpower.com/docs/safety. Security disclosures: [email protected]. Generated from the product data record on 2026-10-21.
