Newly constructed repeater 1W10, powered by purple Hakadi-branded LTO cells, operating at 1W and using a full-wave antenna, is now in test.
(Also in test is newly constructed repeater 1W9, powered by yellow LTO cells branded Huahui New Energy, which you can read about here.)
The 1W10 repeater uses a RAK WisMesh 1W Booster Starter Kit which is SKU 116256. This is the “battery powered” variant for the US915 MHz market. The solar panel is said to be 5 volts and 5 watts. The antenna is a fiberglass 915-MHz antenna with a male N-type connector.
You can see a schematic at right that is very close to what is implemented here, the sole difference being that there are no “prot” boxes in the 1W10 repeater.
The solar panel is connected to the input of an MT3608 buck converter which hopefully has been set (using the potentiometer) to an output of 5.6 volts (measured after the first 1N5404 diode). The converter’s output passes through the 1N5404 diode that was just mentioned. You can see a 5600-μF 40V electrolytic capacitor across the output. The battery is composed of two LTO (lithium-titanate-oxide) cells.
Each cell (seen at right) is an LTO 18650 flat-top cell with nominal voltage 2.4V and rated capacity 1500 mAh. Each cell cost around $3 from Hakadi (shopping cart page). The cells are denoted “bat” in the schematic above.
The top view of the cells (seen at right) shows a contact with four ventilation ports which I assume means there is protective circuitry built into the cell. My assumption is also triggered because the shopping cart page says:
- Charge cut-off voltage: 2.8V, and
- Discharge cut-off voltage: 1.5V.
I take this to mean that there is built-in circuitry in each cell to bleed off as waste heat any charging voltage above 2.8V, and that the circuitry cuts the battery out of the circuit if the battery voltage drops below 1.5V.
Two cells were placed in series to form a battery with nominal voltage 4.8V. It will be appreciated that a potential advantage of these purple cells (when compared with the yellow cells in the 1W9 repeater) is that hopefully no external protection circuitry is needed.
Another potential advantage of these purple cells is that they aspire to a capacity of 1500 mAh as compared with the lower 1300 mAh rating of the yellow cells in the 1W9 repeater.
The charging voltage might be 5.6V which is too high for the radio. (The power input of the radio is intended to be in a range of 1.8V to 5.5V.) So a second 1N5404 diode is used to cut the power supply by about 0.6V, to slightly under 5V.
It is important to recall that the battery connector on the radio is wired “backwards”, so a standard PH2 battery cable needs to be wired using black as positive and red as negative.
Just as in newly constructed repeater 1W9, a Bosch BME280 sensor was added to the radio as described here. This uses the I2C bus of the RAK 19007 baseboard. It measures temperature, humidity and barometric pressure, made available to software at telemetry channel 2.
The repeater is housed in an aluminum weatherproof box (shopping cart page) that is 5.9 by 3.9 by 3.1 inches (150x100x80mm). Here is a list of all of the external penetrations:
- N-type bulkhead female connector on top (for LoRa antenna)
- SMA bulkhead male connector on bottom (for Bluetooth antenna)
- ¼-inch machine screw on bottom (for bracket mounting)
- two 3/16-inch holes on side (for mounting the solar panel)
- one ¼-inch hole on side (for entry of power cable from solar panel)
An effort was made to seal all penetrations with silicone caulk.
At right is a view of the interior of the case. We see the top-mounted N-type connector for the LoRa antenna C. The radio E is secured to the back wall with mounting tape and you can see the PH2 battery cable powering the radio. The Bluetooth connector and mounting stud are at bottom. The large electrolytic capacitor F may be seen. The MT3608 buck converter is oriented so that the adjustment screw of its potentiometer can be reached if the cover is open. You can see a power cable D from the solar panel.
Conspicuously absent in this view (as compared with 1W9) is any external protective circuitry for the battery G.
The radio was flashed with the 0.9.2-OTAFIX2.2-BP1.3 bootloader and v1.17.1-d929643 (Build: 14-Aug-2026) Meshcore repeater firmware. Its test name is 1W10 and the public key is 20BDA1038B693115F3037ECF46AE5BFA63B7AD2434D649C1DD7FE0EF770A8B6D.
The antenna (shopping cart page) is said to have 5.8 dBi gain.
Here are some neighbors:
- Windy Point – 12 dB
- Riley – 11.75 dB
- Ruby Ranch – 11.75 dB
- Ptarmigan – 11 dB
- Cottonwood – 10.75 dB
- Baldy Yagi – 10.75 dB
- Lake Hill – 9.75 dB
- Hamilton Creek – 9.5 dB
- Tenderfoot – 8.25 dB
- Mount Royal – 6dB
- Victoria – -2 dB
- Swan Mountain – -2.5 dB
- Williams Peak – -7.5 dB
Given that the radio draws a quiescent 30 mW, one might expect the battery to last several days without sunlight. The LTO chemistry is said to work down to -40°.