When storing drone batteries (Lithium Polymer/LiPo) for 3 months or more, you are entering Long-Term Storage. If you simply leave them on a shelf fully charged (or empty), they will chemically degrade, puff up (swell), and potentially become a fire hazard.
Here is the protocol for putting your batteries into “Cryostasis” safely.
Phase 1: The “Storage Charge”
The single most important factor is the voltage at which you store the battery.
- The Target: You want the battery at 40–60% charge.
- In Volts: This is 3.80V to 3.85V per cell.
- Why?
- Too High (100%): The chemistry becomes unstable, causing gas buildup (swelling/puffing) and permanent capacity loss.
- Too Low (<20%): The battery naturally self-discharges over time. If it drops below 3.0V per cell, the chemistry collapses, and the battery effectively “bricks” (dies permanently).
How to achieve this:
- Smart Batteries (DJI, Autel, Skydio): Most modern batteries have self-discharge logic. If you charge them to 100%, they will automatically discharge down to 60% after 5–10 days. However, for 3+ months of storage, do not rely solely on this. Manually fly them down to 60% or use a charger with a “Storage” mode to be sure.
- Standard LiPos (FPV/DIY): You must use a balance charger set to “STORAGE” mode. This will automatically charge or discharge the battery to exactly 3.80V per cell.
Phase 2: The Environment
Where you put them is just as important as how you charge them.
- Temperature: Room temperature is ideal (20°C–25°C / 68°F–77°F).
- Myth Busting: Do not store batteries in the fridge or freezer. Condensation inside the wrapper can rust the terminals or short the balance leads.
- Container: Store them in a fireproof LiPo bag or a metal ammo can with the rubber seal removed (to allow venting in case of failure).
- Crucial: Never store batteries inside the drone. If a battery swells or leaks, it will destroy the drone’s internal electronics.
Phase 3: The “90-Day Cycle” Rule
You cannot simply ignore the batteries for 3 months. LiPo chemistry benefits from activity.
Every 3 Months (90 Days), perform this cycle:
- Wake up: Charge the battery to 100%.
- Cycle: Fly the drone (or discharge via charger) down to roughly 15-20%.
- Reset: Charge it back up to the 40–60% storage level.1
Why? This recalibrates the “Smart Battery” chips (BMS) so they accurately read the percentage. If you don’t do this, a battery might say “50%” when it is actually near death, causing a crash when you finally fly again.
Phase 4: Waking Them Up (Post-Storage)
When spring arrives and you are ready to fly:
- Visual Inspection: Check for swelling. If the battery rocks on a flat table (like a warped cutting board) or feels “puffy” like a bag of chips, do not charge it. It is dangerous. Dispose of it.
- Full Charge: The battery may be in “Hibernation Mode.”11 Plug it into the charger and wait. It might take a minute to wake up before the lights turn on.
- Watch the First Flight: The first flight after long storage often has slightly reduced flight time. Don’t push for a long-distance record on your first pack.
Summary Checklist for Long-Term Storage
| Step | Action |
| 1. Charge Level | Discharge/Charge to 40–60% (3.85V). |
| 2. Remove | Take battery OUT of the drone. |
| 3. Protect | Place in a LiPo Safe Bag or Ammo Can. |
| 4. Store | Room temp (70°F), dry place. No Fridge. |
| 5. Maintain | Every 3 months: Charge to full -> Discharge -> Back to storage level. |
