Build Guide: Hilltop Mesh Repeater L
The Hilltop Mesh Repeater L in the field: black ASA-CF, 2 W of solar facing vertically south, antenna directly on the enclosure — with the Inhero MR2.
1. The Concept
The Hilltop Mesh Repeater L is the mast enclosure for demanding sites: 2 W of solar in vertical south-facing mounting, space for up to eleven 18650 cells as an energy buffer, an N bulkhead jack for the direct antenna connection and a clamp for 30 mm masts. The design follows the principle of buffer instead of panel area: the enclosure stays small and low in wind load, while the reserve for overcast spells sits in the battery — in the full configuration with eleven cells, around 70 days of autonomy without meaningful solar yield. The complete design rationale is described on the kit page and in the article Why the MR2 Exists.
The enclosure consists of two main parts: the base carrier with the battery compartment, MR2 mount and lower clamp shell, and the hood, which carries the two solar modules, the antenna mount and the upper clamp shell. The base carrier is fully populated and wired first, then the hood goes over it — the mast clamping holds both parts on the tube.
Not a submarine: Many makers build very tight enclosures, some with a pressure-equalization membrane or a 1 mm drain hole in the bottom. The Inhero enclosures deliberately take the opposite approach: airy by design, with no sealed volume. There is no trapped moisture and no condensation problem, yet the electronics are reliably protected from the weather. This concept has proven itself in the field over years.
2. Parts List
2.1 From the Shop (included in the kit)
| Pos. | Component | Qty |
|---|---|---|
| 1 | MR2 solar mesh repeater board | 1 |
| 2 | U.FL retaining clip, ready-printed (PETG) — included with every MR2 | 1 |
| 3 | Solar panel 6 V / 1 W with pre-soldered cable | 2 |
| 4 | Solar connector board (parallel connection of the panels) | 1 |
| 5 | Connection cable for the solar connector board | 1 |
| 6 | MR2 battery cable — choose variant: LiFePO4 or Li-ion protection module, or without BMS (LTO/Na-ion) | 1 |
| 7 | Pigtail N bulkhead jack → U.FL, 15 cm | 1 |
| 8 | BLE adhesive antenna 2.4 GHz, U.FL | 1 |
| 9 | Screw set for MR2 mounting (stainless steel A2, Ø 2.5 × 4.5 mm, T8) | 1 |
| 10 | Stainless steel bolt set for mast mounting (4 × M6×60 mm pan head TX30, ISO 7380-2, + 4 × M6 nuts) | 1 |
| 11 | ZIISOR 868 MHz fiberglass antenna with N-male connector — depending on the chosen kit variant: 3 dBi (26 cm), 5.5 dBi (40 cm) or 8 dBi (55 cm); not included with the “no antenna” variant | 1 |
2.2 To Source Separately (not in the kit)
| Component | Qty | Note |
|---|---|---|
| 18650 cells — matching the chosen battery cable variant! | up to 11 | LiFePO4 or Li-ion; the without-BMS variant is intended for LTO (2S, external balancer) and Na-ion cells — details in the battery chemistry guide. The photos show the build with LiFePO4 (3.2 V / 2200 mAh). Recommendation: cells with pre-welded solder tags, otherwise a spot welder. |
| Antenna with N-male connector — only with the “no antenna” kit variant | 1 | Omni antenna with N-male connector; the pictures show the build with the ZIISOR 8 dBi fiberglass antenna. Please note: the sealing bushing is dimensioned for the base diameter of the ZIISOR fiberglass antennas; all three ZIISOR models share the same base. Antennas with a different base diameter cannot be sealed properly against it. |
| Filament | — | Weather- and UV-resistant — very well suited: ASA-CF. On color choice, see the note in section 3. |
| Adhesive/sealant: WEICON Flex+bond, 85 ml, transparent | 1 | MS polymer, permanently elastic — bonds the solar modules and the antenna-base sealing bushing to the hood |
| Adhesive-lined heat-shrink tubing | — | seals the transition from the sealing bushing to the antenna |
| Small parts | — | Kapton tape, fabric tape, spiral wrap, insulation material for the battery pack |
2.3 Tools
Soldering iron, spot welder (only for bare cells), Torx bits T8 (MR2 screws) and TX30 (mast clamp), side cutters, multimeter for matching cell voltages, hot air for the heat-shrink tubing. No wrench is needed — the M6 nuts sit captive in the hex pockets.
3. Printed Parts
STL files: free download in the shop. The set consists of three parts: the base carrier (battery compartment, MR2 mount, lower clamp shell), the hood (panel recesses, antenna mount, upper clamp shell) and the sealing bushing for the antenna base — the clamp jaws are integrated into base carrier and hood. Everything fits on one build plate. The U.FL retaining clip is not self-printed — it comes ready-printed in PETG with every MR2, because PETG has the elasticity needed for clipping while the brittle ASA-CF is unsuitable for it.
Color choice: Both enclosures shown are printed in ASA-CF — the one in this build guide in gray, the installed repeater in the title picture in black. Gray heats up considerably less in the summer sun and is the thermally more relaxed choice for the battery; black is less conspicuous at the site. The inside temperature can be monitored via the MR2's telemetry.
All printed parts on one plate: the base carrier with the battery compartment on the left, the hood on the right — note the hex pockets for the M6 nuts.
Top view of the arrangement: base carrier on the left, the sealing bushing (ring) and the integrated clamp shells in the middle, the hood on the right.
Set painted-on supports at the upper edges of the two panel recesses: pick the fill tool and click the edge — the smart fill angle governs how far the marking spreads. It should catch exactly the narrow strip; if it runs too far or stops short, adjust the angle accordingly. The automatic detection does not reliably catch these small overhangs — and without clean upper edges the modules will not sit flush in the recesses later.
4. Mounting the N Bulkhead Jack and Antenna
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Insert the pigtail's N bulkhead jack into the antenna mount of the hood from the inside and counter it from the outside.
Outside and inside view: the jack sits in its mount next to the mast clamp; inside, the thin pigtail cable leads to the later LoRa connection.
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Slide the sealing bushing over the antenna base and screw the antenna onto the N jack.
Antenna installation with the sealing bushing slid on — here with the ZIISOR 8 dBi fiberglass antenna. Gluing happens in the next step.
5. Gluing the Sealing Bushing and Solar Modules
Gluing is done with WEICON Flex+bond: the sealing bushing at the antenna base and both solar modules.
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Apply an adhesive bead around the foot of the sealing bushing, slide the bushing down onto the hood and rotate it several times while doing so — the rotation spreads the adhesive evenly across the entire seat.
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Do not press too hard: a sufficient adhesive layer must remain — the permanently elastic layer seals and absorbs movement and thermal expansion.
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Apply a perimeter adhesive bead to the backs of the solar modules, thread the cables through the pass-throughs in the panel recesses and insert the modules. The same rule applies: press gently, leave the adhesive layer standing.
6. Building the Battery Pack
Use only undamaged brand-name cells. The cell chemistry must match the ordered battery cable variant. For LiFePO4 and Li-ion, the protection module is a mandatory component, not an accessory. Mind the polarity. Never solder directly onto the cell can.
Important — balance before every parallel connection: all cells must be brought to the same voltage before connecting, maximum 10 mV difference (multimeter!). If cells at different voltages are connected in parallel, high equalizing currents flow instantly — quite literally: sparks fly.
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Base pack: connect seven cells in parallel in a row. The protection module sits at the position in the pack for which the recess in the base carrier is provided. When welding, use the base carrier's battery compartment as a spacing jig — that way the pack geometry matches the compartment later. Protect the lead with spiral wrap.
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Insert the base pack into the battery compartment of the base carrier and secure and insulate it with fabric tape. The protection module rests in its recess.
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Full configuration: two 2-cell bundles in the upper recesses left and right — eleven cells in parallel. Wrap the bundles in Kapton tape and match them to the base pack's voltage before connecting (max. 10 mV difference). Work cleanly and with full concentration: a pack of this size carries a serious short-circuit risk.
7. Mounting the MR2
Caution: switch off the MR2 with the DIP switch before connecting the battery, and never power it on without the LoRa antenna connected — otherwise risk of damage to the LoRa TX. Mind the inverted switch logic: switch position “On” activates “3.3V off” (as printed on the silkscreen) — the board is then off. The LoRa pigtail is connected only when the hood is fitted.
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Mount the MR2 on the base carrier with the four supplied T8 screws, stick the BLE adhesive antenna to the side and connect it, plug in the battery cable.
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Check: MR2 mounted, battery cable and BLE antenna connected, cables secured with fabric tape.
8. Fitting the Hood and Wiring
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Fit the hood and wire everything up: plug both solar modules into the solar connector board, route the connection cable to the MR2's solar input, and push the antenna pigtail onto the LoRa U.FL connector of the RAK module.
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Fit the U.FL retaining clip (included with the MR2) over the RAK module. The clip is no gimmick: when sliding hood and base carrier together, the LoRa antenna's U.FL connector can pop off unnoticed — for a repeater on a mast, the worst case there is. The clip mechanically secures the U.FL connections; the reset button remains accessible.
9. Final Assembly and Sealing
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Insert the four M6×60 screws (TX30) into the clamp shells and pre-assemble them loosely. The M6 nuts sit captive in the hex pockets. Hand-tight only — final tightening happens at the mast, following the procedure in section 11.
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Seal the transition to the antenna with adhesive-lined heat-shrink tubing. The tubing covers sealing bushing and antenna base; the hot-melt adhesive inside seals permanently.
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Done.
10. Configuring the MR2
Firmware: The MR2 ships without application firmware (OTAFIX bootloader only). Flashing is most convenient before enclosure assembly (section 7), while USB-C is freely accessible. Two prerequisites: the LoRa antenna must be connected — after flashing, depending on the firmware version, transmission by the repeater cannot be ruled out — and the board must be switched on, otherwise flashing does not work. Mind the inverted switch logic: switch position “On” activates “3.3V off” (silkscreen label), the board is then off — so for flashing and operation the switch is set to “Off”. Then: press the reset button twice in quick succession (double reset), the board mounts as a USB drive, copy the .uf2 file via drag and drop. Ready-made, tested MeshCore builds for the MR2 are available in the firmware releases on GitHub.
To configure, switch the MR2 on — both antennas have been connected since section 8 — and connect via the MeshCore app using the admin access. In the command line, the board is adapted to the build. The values for the full configuration of this kit (eleven LiFePO4 cells of 2200 mAh, 2 W of solar):
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set board.bat lifepo1s— cell chemistry 1S LiFePO4; defines the charge-termination, sleep and protection thresholds. -
set board.batcap 22000— always set the battery capacity to match the cells actually fitted, following the 90% rule: cell capacity × number of cells × 0.9. Here, eleven cells of 2200 mAh = 24,200 mAh nominal capacity, of which roughly 90%. The deduction makes the SOC display and the runtime prediction conservative — when 10% is shown, at least 10% really is in the battery (FAQ #4). -
set board.imax 600— maximum charge current following the rule of thumb panel power ÷ battery voltage: 2 W ÷ 3.2 V ≈ 600 mA. A value set too high makes the panel voltage collapse in weak light and the charger stops (FAQ #5). -
set board.fmax 20%— frost protection: around the freezing point (approx. +3 to −2 °C) the charge current is limited to 20% of imax; below that, charging is fully blocked for LiFePO4 by chemistry. The repeater keeps running on solar regardless — only charging is limited (FAQ #6). -
set board.mppt 1— enable MPPT. -
set board.leds 0— board LEDs off: they save power and are invisible inside the closed enclosure anyway.
Check: get board.conf shows all configured values at a glance, get board.selftest probes the onboard components. Then fully charge the battery once (e.g. via USB-C): the coulomb counter needs one full charge as its 100% reference — until then, the SOC shows “N/A”. For a different configuration (Li-ion, fewer cells), adjust board.bat and board.batcap accordingly; all commands are explained in the CLI reference.
11. Location & Mast Mounting
- Orientation: solar surface vertical and facing south. The large battery buffer forgives partial shading and less-than-ideal orientation — that is exactly what the L is designed for.
- Mounting — clamp for a 30 mm mast, tighten the screws (TX30) very carefully: two screws pull in parallel per clamp shell. Tightening one loosens the other — anyone who then forcefully alternates adds up the tensile forces and cracks the ASA-CF. Therefore: per shell, tighten alternately and in very small increments until the clamp sits firmly on the tube. No tighter than necessary. Order: first fully set the lower shell on the base carrier, then the upper one on the hood.
- Radio: every meter of height adds range — and short antenna paths remain the principle: the antenna sits directly on the enclosure, 15 cm of pigtail, no cable losses.
- Energy: 2 W vertical south keeps the MR2 in an energy surplus year-round in Central Europe. In the full configuration (11 × 2200 mAh) there are around 70 days of autonomy without meaningful solar yield — this repeater keeps running. And should the battery ever run empty after all, the MR2 goes into deep sleep and wakes up on its own once the sun has recharged the battery.
12. Legal & Safety
- The kit contains tested, compliant individual components (MR2: CE/RED). Final assembly is carried out by the buyer at their own responsibility for personal use.
- This guide was written to the best of our knowledge but does not replace expertise. Handling lithium cells requires care: the instructions in section 6 — matching cell voltages before connecting in parallel, protection module, insulation, short-circuit risk — are mandatory. Building this project is at your own risk; no liability is accepted for damage resulting from improper assembly or unsuitable components, to the extent permitted by law.
- Operation in the 868 MHz band in accordance with the applicable regulations (duty cycle); the MR2 enforces these in firmware.
© Inhero GmbH · shop.inhero.de · Enclosure design (STL/3MF files) licensed under CC BY-NC-SA 4.0 — private reprinting and further development expressly welcome · Version 1.3