Off-Grid Field Production Pod Guide

Summary¶

After reading this guide, the operator can design and deploy a self-contained field pod capable of charging batteries, repairing hardware, and printing replacement parts independently of grid power. This is the 3.0.0 replacement for the V2.4.6 Field Pod document, inspired by frontline Ukrainian drone workshop practice (MZAK1, Nebokray) and adapted for 1–5 person civilian resilience and survey teams.

Concept¶

Why the field pod exists¶

The libdrone workshop in Telč has a grid connection. Most of the time this is invisible. When the grid fails — which is exactly when drone capability is most needed — a drone platform without field power independence is a demonstration piece, not a preparedness asset.

Ukraine provided the specific lesson: small drone teams that can operate without infrastructure are disproportionately effective. The ability to charge batteries, repair a broken arm, and print a replacement part in a field environment — without grid power, without a fixed location, without a logistics chain — is the difference between a deployable capability and an equipment inventory.

Power budget — what libdrone actually draws¶

Before sizing any generator or battery, the actual loads must be established. Three realistic simultaneous scenarios define the requirements:

Charging only (~240W): two 6S packs at 2C on HOTA D6 Pro plus laptop. This is the recovery scenario after a flight session.

Charging plus repair (~335W): two packs charging, soldering station active, laptop, and field lighting. The most common field scenario.

Full production (~540W): Prusa CoreOne+ printing a replacement arm plus two packs charging plus laptop and lighting. The demanding scenario required when structural parts are damaged mid-deployment.

Peak spike (~1000W): printer bed warming up simultaneously with charger at maximum. This is brief but must not trip a generator's thermal protection.

The minimum generator specification for full production capability: 1200W continuous, 2000W peak. An inverter generator (sine wave output) is required for the Prusa CoreOne+ — PWM-modulated generator output causes printer electronics errors.

Power system options¶

Generator path (higher initial cost, maximum capability): Honda EU22i or equivalent inverter generator. 2200W peak, clean sine wave, quiet operation (~53 dBA at 7m). 3.6L tank at eco mode ≈ 4–5 hours. The standard Czech recommendation for field production capability.

LiFePO4 battery path (lower noise, weather-independent): a 48V 50Ah LiFePO4 pack (2.4 kWh) can sustain the charging-only scenario (~240W) for approximately 8 hours or a single full production cycle (1.5–2 hours at 540W average). Recharges from generator in ~3 hours. The combination — LiFePO4 for routine operations, generator for extended or high-demand sessions — is optimal.

Solar supplement: a 400W foldable solar panel array in summer conditions contributes approximately 200–240W average in Central European daylight, covering the charging-only load. Not a primary power source for full production.

Battery charging in the field¶

→ lipo-batteries covers the charging rules that apply regardless of field or home context. The field-specific constraints:

Field charging requires LiPo charging bags (ammo boxes preferred for puncture resistance). Never charge inside an enclosed vehicle. In temperatures below 10°C, allow 30 minutes warm-up time before starting any charge cycle. → winter-protocol covers the cold-weather voltage threshold adjustments.

The HOTA D6 Pro at 2C on two 1800mAh 6S packs draws approximately 200W and completes a charge in 30 minutes. In a field rotation: fly (12–15 min), charge (30 min), fly. Two packs give a 30-minute continuous rotation.

Printing in the field¶

The Prusa CoreOne+ is the specified printer. → print-profiles covers the profiles that govern field print quality. Field-specific constraints:

The printer requires a level, vibration-free surface. In a vehicle or temporary shelter, a dedicated table with non-slip pads is required. PCCF printing requires enclosure temperature ≥25°C — in cold field conditions, an insulated tent or vehicle cabin is the enclosure.

Field priority print sequence: arm shafts first (20 minutes each, most likely needed), then bumpers (high crash frequency), then structural PCCF layers only if a major structural failure requires them.

Filament storage in the field: PETG and PCCF are moderately hygroscopic. Keep in sealed bags with silica gel. Filament that has absorbed moisture produces stringing and poor layer adhesion.

Pod configuration¶

Minimum mobile kit (backpack deployable, all-charging no printing): HOTA D6 Pro charger, 3× LiPo ammo boxes, 3× 6S packs, laptop, 2.4 kWh LiFePO4, inverter (600W), cables, field bag.

Full production pod (vehicle deployable, charging + repair + printing): All of the above plus Prusa CoreOne+, Honda EU22i generator, SEQURE soldering station, filament stock (PETG, PCCF, ASA), tools.

Winter field operations¶

→ winter-protocol applies in full. Additional field-specific requirements: Generator fuel viscosity changes below −10°C — use winter-grade fuel. LiFePO4 capacity drops approximately 20% at −10°C. LiPo charging at temperatures below 0°C must not be attempted — allow warm-up in the vehicle cabin first.

The drone itself should not fly below 0°C in standard configuration — → winter-protocol explains why PETG arm shaft brittleness and LiPo sag both become significant below this threshold.

Reference¶

Field pod power system sizing¶

Scenario	Peak draw	Recommended power source
Charging only	~240W	LiFePO4 2.4 kWh alone (8h endurance)
Charging + repair	~335W	LiFePO4 + small generator backup
Full production	~540W	Honda EU22i or equivalent
Peak spike (brief)	~1000W	Generator with ≥2000W peak rating

Minimum field spares list¶

Item	Quantity	Why
PETG arm shafts (printed)	10	Most common repair
Bumpers ASA	8 + 4 spare	High crash frequency
Props HQProp 6" (both pitches)	2 full sets	Any prop damage grounds flight
Motors 2507 1750KV	2	Bearing or winding failure
MR30 connector pairs	5	Motor connector damage in crashes
RP2 ELRS receiver	2	Antenna damage common
Silicone O-rings ID4/OD7	20	Motor mount maintenance
Loctite 243	1× tube	Rod pinch bolts
Conformal coating (HPA200H)	1× aerosol	Post-repair coating

Procedure¶

Field pod deployment sequence¶

Level and secure printing surface before printer arrives
Generator: check oil, check fuel, run for 5 minutes before connecting any electronics load
LiFePO4: check state of charge before departure — arrive with full pack
Print 2 spare arm shafts on arrival at any new deployment site
Establish charging rotation: charge between flights, not during

Rationale¶

The V2.4.6 Field Pod document was a standalone community document with full power budget calculations, worked examples, and BOM. The 3.0.0 skeleton delegates the LiPo handling rules to → lipo-batteries, the winter protocol to → winter-protocol, and the print profiles to → print-profiles — this skeleton provides the field-deployment architecture that connects them.