DIY LiPo Charging Case: Portable Safe Transport and Field Charging
A purpose-built LiPo charging case is the most important safety investment an FPV pilot can make. It contains thermal runaway events, organizes your charging equipment, and enables safe field charging from a large-capacity DC source. This guide covers the complete design and build of a portable charging case that balances fire safety, portability, and practical usability for day trips and multi-day events.
Design Requirements
A well-designed charging case must satisfy five requirements simultaneously. Fire containment: if a LiPo enters thermal runaway, the case must contain the fire, filter the smoke, and prevent propagation to adjacent packs. Heat management: chargers and power supplies generate significant heat during operation, and the enclosure must provide adequate ventilation. Portability: the case must be carryable by one person, with all components secured against movement during transport. Organization: cables, balance boards, adapters, and tools need dedicated storage that doesn’t interfere with the charging workflow. And power integration: the internal power supply, wiring, and output connectors must be sized appropriately for the charging load and protected against shorts and overloads.
Parts List
| Component | Specification | Estimated Cost (USD) | Notes |
|---|---|---|---|
| Hard case | Pelican 1550 or Apache 5800 | $80–180 | Waterproof, crush-resistant, internal volume ~25L |
| DC power supply | Mean Well LRS-350-24 or RSP-500-24 | $40–90 | 24V output, 350W–500W. One per two chargers |
| LiPo charger | ISDT Q8 Max or HOTA D6 Pro (×2) | $60–120 each | DC-input chargers preferred; AC/DC dual-input acceptable |
| AC inlet module | IEC C14 fused inlet with switch | $8–15 | 10A fuse, illuminated switch for visual power status |
| DC output panel | XT60 panel mount connectors (×4–6) | $3–8 each | One per charger output; extras for accessories |
| AC power strip | Compact 3-outlet, no surge protector | $10–15 | Hardwired internally; surge protectors unnecessary for PSU |
| Ventilation fans | 80mm or 120mm 12V/24V DC fans (×2) | $8–15 each | One intake, one exhaust. Noctua or Arctic recommended |
| Fan controller | 12V/24V PWM fan speed controller | $8–12 | Temperature probe controls fan speed automatically |
| LiPo storage compartment | Bat-Safe mini or steel ammunition can | $30–60 | Secondary containment inside the main case for stored packs |
| Vent grilles | 120mm round or rectangular metal grilles (×2) | $5–10 each | Steel preferred; prevent debris ingress |
| Wiring and connectors | 12AWG silicone wire, XT60 connectors, ring terminals | $20–30 | Silicone insulation resists heat during thermal event |
| Miscellaneous | M3/M4 hardware, zip ties, VHB tape, foam padding | $15–25 | Stainless steel hardware preferred for corrosion resistance |
| Total estimated cost | $340–670 | Varies significantly with case and charger choices | |
Step 1: Case Selection and Layout Planning
The Pelican 1550 (or the nearly identical Apache 5800 from Harbor Freight) offers approximately 47 × 36 × 19cm of internal space—sufficient for two chargers, a power supply, fan system, and a LiPo storage compartment. These cases feature a pressure equalization valve and are rated IP67 when closed. The critical modification is cutting ventilation holes through the case walls, which compromises the waterproof rating but is essential for cooling.
Before cutting anything, lay out all components inside the case and plan cable routing. The general arrangement that works best: power supply and AC inlet on the left side, chargers mounted to the lid or on a raised panel on the right side, LiPo storage in a steel container in the bottom, and fans at opposite corners for cross-flow ventilation. Leave at least 5cm of clearance around the power supply for airflow and ensure that the intake fan blows directly across the power supply and charger heat sinks.
Step 2: Ventilation Installation
Ventilation is the most structurally invasive part of the build. Use a 120mm hole saw for the fan cutouts—the plastic cuts cleanly at low speed. Position the intake fan on the lower left side and the exhaust on the upper right, creating a diagonal airflow path that passes over all heat-generating components. Mount the fans with M4 bolts through the case wall, using rubber gaskets or silicone washers to reduce vibration transmission.
The fan airflow direction is critical. The intake fan should blow into the case; the exhaust should blow out. Both fans should be filtered with metal grilles on the exterior and a fine mesh screen on the interior to prevent debris ingress. Wire both fans to the PWM controller with the temperature probe positioned between the power supply and the nearest charger heat sink. Set the controller to start the fans at 35°C and ramp to full speed by 45°C.
Step 3: Power Supply Integration
The Mean Well LRS-350-24 provides 350W at 24V DC—sufficient for two chargers running at approximately 150W each. For higher charging rates (e.g., parallel charging multiple 6S 5000mAh packs), upgrade to the RSP-500-24 (500W). Mount the power supply on standoffs at least 10mm above the case floor to allow airflow underneath. The power supply chassis must be grounded to the AC earth conductor.
AC wiring: the IEC C14 inlet module connects to AC mains through a standard computer power cable. The line and neutral conductors go to the power strip inside the case; the earth conductor goes to a dedicated ground stud bolted through the case wall. The power supply and any AC-powered accessories plug into the internal power strip. Use ring terminals, not bare wire, for all AC connections. Cover all AC terminals with insulating boots or heat shrink. The fuse in the IEC inlet should be rated at 10A for 120V systems or 5A for 230V systems—this is the primary overcurrent protection.
DC wiring: Run 12AWG silicone wire from the power supply output to a distribution block or directly to the DC input connectors for each charger. Each charger should have a dedicated XT60 input on the panel. Fuse each output at 20A with automotive blade fuses or inline XT60 fuse holders. The power supply’s output voltage should be adjusted to 24.0V using the trim potentiometer, measured at the charger input under load to account for voltage drop in the wiring.
Step 4: Charger Mounting and Interface Panel
Charger mounting strategy depends on your workflow. Lid-mounted chargers are easy to access when the case is open and sitting on a table, but the lid must be stabilized to prevent it from closing during use. Floor-mounted chargers keep the center of gravity low but are harder to read and operate. A popular compromise is a hinged panel that folds up when the case is open, presenting the chargers at a comfortable viewing angle.
The charger interface panel should include: one XT60 input per charger (connected to the power supply output), one XT60 output per charger channel (routed through the panel to the battery connection area), and one 4S or 6S balance port per channel on panel-mount balance boards. Panel-mounting the balance ports prevents the fragile balance leads from being tugged during charging. Label every connector clearly—a permanent label maker is worth the investment.
Step 5: LiPo Storage Compartment
This is the fire safety subsystem of the case. A Bat-Safe mini (200×150×150mm internal) fits inside most 1550-class cases and provides independently tested fire containment for up to two 6S 1300mAh packs or one 6S 5000mAh pack. The Bat-Safe uses a steel box with a filtered vent that allows gases to escape while trapping particulates and cooling the exhaust below the auto-ignition temperature of surrounding materials.
If using a steel ammunition can, remove the rubber lid seal—this is critical. During a thermal runaway event, the decomposing electrolyte generates rapidly expanding gases that must vent. A sealed container becomes a pressure vessel and can rupture explosively. Without the seal, gases escape through the lid gap while the steel construction provides thermal containment. Fill the bottom of the ammo can with 2–3cm of dry sand as an additional heat sink.
Position the LiPo storage compartment away from the power supply and chargers. If possible, place it in a separate section of the case isolated by a steel or aluminum divider. The goal is to ensure that a thermal event in the storage compartment does not directly heat the power supply or chargers, which would create cascading failures.
Fire Safety Considerations
No charging case is fireproof. A LiPo thermal runaway event reaches temperatures of 600–800°C and generates its own oxygen, making it impossible to extinguish by smothering. The charging case’s role is containment and time: it should contain the fire long enough for you to move the case to a safe location (outside, onto concrete) and for the reaction to burn itself out without igniting the surrounding area.
Critical safety rules for field charging:
- Never charge unattended. Stay within visual range of the case while packs are charging. A thermal runaway event announces itself with a distinctive hissing sound and thick white smoke 5–30 seconds before flames appear.
- Charge on a non-flammable surface. Even with the case, place it on concrete, gravel, or bare earth—not on a wooden table, inside a vehicle, or on dry grass.
- Keep a fire extinguisher accessible. A CO2 or dry chemical extinguisher rated for electrical fires (Class C) can suppress secondary fires. It will not stop a LiPo thermal runaway but may prevent it from spreading.
- Know the escape plan. If a pack goes into thermal runaway, close the case lid (if safe to do so), move it away from people and vehicles, and evacuate upwind of the smoke. The smoke is toxic—hydrogen fluoride, carbon monoxide, and various organic compounds.
- Charge at 1C or below in the field. Higher charge rates generate more heat and increase the probability of a thermal event. Fast charging at 2C or above should only be done with packs you know intimately well, in a controlled environment.
Field Power Options
The charging case described above is designed for AC mains power. For true field charging where AC is unavailable, add a DC input option. A 6S or 12S LiPo field battery (typically a large-capacity LiPo in the 10,000–22,000mAh range) can power the chargers directly through their DC inputs, bypassing the internal AC power supply entirely. Install an XT90 or XT120 connector on the case exterior, wired through a high-current switch, to accept field battery input.
A 6S 22,000mAh field battery stores approximately 490 watt-hours. Charging four 6S 1300mAh packs (which each require about 28 watt-hours for a full charge from storage voltage) consumes roughly 112 watt-hours, giving you four full charge cycles per field battery. For multi-pilot sessions, a 12S deep-cycle LiFePO4 battery (48V nominal, 50–100Ah) provides 2,400–4,800 watt-hours—enough for a full day of charging for a small group.
Building a dedicated charging case is a weekend project that permanently improves your charging workflow and safety posture. The cost is comparable to two or three quality LiPo packs, and the peace of mind—knowing that your charging setup won’t burn down your house or your vehicle—is invaluable.