Guides
Gorilla Whoop Whoop Guide: Basics of Drone Battery Tech
This guide explains the batteries that power a small FPV drone: what the numbers on the label mean, which voltages matter, how to charge and store packs safely, and how to tell a healthy pack from a failing one. The examples come from a BetaFPV Air75 whoop running Betaflight on 1S packs.
The battery powers everything on the drone at once: motors, flight controller, receiver, video transmitter and camera. When it sags, everything feels it. When it's damaged, it can catch fire.
| My setup | |
|---|---|
| Packs | OVONIC 850 mAh 1S LiHV, 3.8 V nominal, 4.35 V full, 100C claimed, 4-pack |
| Connector | BT2.0 |
| Pack weight | About 14–17.5 g each, against a ~21 g drone. BetaFPV recommends 450 mAh for the Air75 |
| Flight time | Roughly 3–4 minutes, less when flying hard |
| Charger | Multi-port 1S charger |
Glossary
| Term | Means |
|---|---|
| LiPo | Lithium polymer. Full at 4.20 V per cell |
| LiHV | High-voltage LiPo. Full at 4.35 V per cell. Common on whoops |
| Li-ion | Like 18650 cells. High capacity, poor at bursts of current. For long-range cruising, not whoops |
| S | Cells in series. 1S = one cell; 4S = four cells, 4× the voltage |
| mAh | Milliamp-hours: capacity, the size of the tank |
| C rating | Claimed safe discharge rate. Mostly marketing |
| Sag | Voltage dip under throttle that recovers when you let off |
| IR | Internal resistance, in milliohms. The best health indicator; rises as a pack ages or gets damaged |
| Puffing | The pack swelling. A sign of damage: retire it |
| Storage charge | Half-full voltage for resting: ~3.80 V LiPo, ~3.85 V LiHV |
| Balance lead | Wire for checking each cell. Not needed on 1S |
| vbat | Betaflight's name for battery voltage |
Voltage: the numbers that matter
A lithium cell's voltage is its fuel gauge.
| State | LiPo (per cell) | LiHV (per cell) | Meaning |
|---|---|---|---|
| Full | 4.20 V | 4.35 V | Ready to fly. Don't leave it full for days |
| Nominal | 3.70 V | 3.80 V | The rating printed on the label |
| Storage | ~3.80 V | ~3.85 V | For more than a day or two between sessions |
| Land soon (under load) | ~3.5 V | ~3.5 V | My OSD warning level |
| Empty (resting) | ~3.3 V | ~3.3 V | Stop here |
| Damaged | below ~3.0 V | below ~3.0 V | Permanent damage likely. Don't charge it |
Sag
Under throttle, internal resistance pulls the voltage down; let off and it springs back. A pack can read 3.4 V mid-punch and 3.7 V a second later. So the warning flickering on hard punches is normal. When it shows during gentle flying, land.
In Betaflight
| Setting | Where | My value |
|---|---|---|
| Warning cell voltage | Power & Battery tab, or vbat_warning_cell_voltage | 3.5 V (350) |
| Minimum cell voltage | Power & Battery tab, or vbat_min_cell_voltage | 3.3 V (330) |
| OSD elements | OSD tab | Average cell voltage, mAh used |
The CLI uses hundredths of a volt: 350 means 3.50 V. The Air75's current sensor also lets Betaflight count mAh used, a steadier fuel gauge than voltage because it doesn't bounce with sag.
The board's voltage reading depends on the right firmware target. On the wrong one (V3 on my V2 board), the sensor read the wrong pin. Betaflight 2026.6 also added switchable battery profiles for flying packs of different sizes.
Capacity, C rating and connectors
Capacity vs weight
More mAh means longer flights but a heavier drone, and on a 21 g whoop the battery is one of the heaviest parts.
| Pack | Flight time | Feel |
|---|---|---|
| Smaller (~300–450 mAh) | Shorter | Lighter, snappier, gentler crashes |
| Larger (550 mAh and up) | Longer | Heavier, more momentum, harder hits |
Doubling capacity doesn't double flight time, because the drone has to carry the extra weight. My 850 mAh packs weigh roughly three-quarters as much as the drone itself.
C rating
The claim: max current = capacity × C. My 850 mAh 100C pack claims 0.85 A × 100 = 85 A. A whoop pulls a few amps cruising and maybe 10–15 A on a hard punch, so almost any decent pack is enough on paper. C ratings aren't standardized and are often inflated. What actually shows a pack's strength: sag under throttle and internal resistance on the charger.
Connectors
| Connector | Used on | Notes |
|---|---|---|
| PH2.0 | Older/small brushed whoops | Higher resistance, more sag |
| BT2.0 | The Air75, most BetaFPV whoops | Larger pins, less sag |
| A30 | Some newer whoops | Slim, low resistance |
| XT30 | 2S+ micros and toothpicks | More current |
| XT60 | 4S–6S 5-inch quads | Full-size standard |
These aren't interchangeable. Adapters add resistance, which a 1S whoop can't spare. Inspect the plug often: a loose, bent or blackened connector adds sag.
Charging
The basics
- Match the chemistry. LiPo charges to 4.20 V, LiHV to 4.35 V. Charging a regular LiPo in LiHV mode overcharges it, which is a real fire risk.
- Charge at 1C or less. 1C in amps = capacity in Ah.
- No balance lead on 1S. One cell, nothing to balance.
- Multi-port 1S chargers charge each pack on its own port, and the amp setting is usually per port.
Charge current for 850 mAh packs
| Setting | C rate | Verdict |
|---|---|---|
| 0.5 A | ~0.6C | Gentlest. Use for suspect packs |
| 0.8–0.9 A | ~1C | Ideal everyday setting |
| 1.0 A | ~1.2C | Fine for healthy packs |
| 1.7 A or more | 2C+ | Avoid unless the pack is rated for fast charging |
Slower is never harmful, just slower. A healthy pack charging at 1C stays around room temperature; one that gets warm should be unplugged and retired.
Charging safely
- Charge on a non-flammable surface, ideally in a LiPo-safe bag or metal box.
- Never charge unattended, and never overnight.
- Let hot packs cool first.
- Never charge a pack that's puffy, dented, punctured, or has been drained below ~3.0 V.
- Have a fire plan. Sand, a metal container, or getting it outside matter more than a household extinguisher.
Storage
- More than a day or two before the next flight: bring packs to storage voltage (~3.85 V LiHV). Many chargers have a storage mode, or fly them halfway down.
- Packs left full for days age faster and can start to puff.
- Store cool, dry, and away from anything flammable.
Temperature
Cold packs can't deliver current well: they sag harder, flights get shorter, and the low-voltage warning can come on almost immediately.
- Keep packs at about room temperature before flying: an inside pocket, or hand warmers next to them.
- Warm, not hot. Never on a heater or in a hot car.
- A pack too hot to hold comfortably after a flight has been pushed too hard.
Battery health
| Sign | What it means | What to do |
|---|---|---|
| Shorter flights than its siblings | Lost capacity | Practice pack, or retire |
| Warning comes on early, heavy sag | Rising internal resistance | Compare IR on the charger |
| IR much higher than its siblings | Ageing or damage | Retire soon |
| Voltage drops overnight after charging | Internal damage | Retire |
| Gets hot in normal flying | High resistance or damage | Retire |
| Puffy, swollen, dented, punctured | Damaged | Retire now. Don't fly or charge it |
Number your packs with a marker. It's the only way to track which one is acting up.
Testing a suspect pack
- Mark it so it doesn't get mixed in.
- Look for puffing. If it's puffy, stop: retire it.
- Charge all packs at 0.5 A and compare IR readings.
- Note the voltage after charging, then again the next day. A good pack barely moves.
- Fly it against a good pack. Compare flight time and how early the 3.5 V warning appears.
Disposal
Don't throw LiPos in the trash. Discharge them fully (many chargers have a discharge mode), then take them to a battery recycling drop-off.
Case study: did I overcharge mine?
One or two of my packs started acting strange, and I suspected either overcharging or over-draining.
- Overcharging: no. The packs are LiHV (3.8 V nominal), full at 4.35 V. I'd been charging to 4.2 V, which is slightly under full: safe, gentler on the cells, and only about 5–10% less flight time.
- Over-draining: likely. Going below ~3.0 V damages a cell permanently. On a whoop it happens by flying past the warning, or by leaving the drone powered after a crash while you go find it.
The fix is habits: land when the 3.5 V warning shows in normal flying, unplug right after a crash, and storage-charge between sessions.
Quick reference
| Question | Answer |
|---|---|
| Full LiPo / LiHV? | 4.20 V / 4.35 V per cell |
| When to land? | When the 3.5 V warning shows in normal flying |
| Empty? | ~3.3 V resting. Don't go lower |
| Storage voltage? | ~3.80 V LiPo, ~3.85 V LiHV |
| Charge current? | 1C or less. 850 mAh: 0.8–0.9 A ideal, 1 A fine, 0.5 A for suspect packs |
| Balance lead on 1S? | Not needed |
| Is a higher C rating better? | Not reliably. Watch sag and IR |
| Puffy pack? | Retire it. Don't fly or charge it |
| Voltage jumping around? | Sag. Normal unless extreme |
| Cold day? | Keep packs warm until you fly |
| Air75 connector? | BT2.0 |
Sources
- OVONIC 850 mAh 1S 3.8 V HV 100C BT2.0 (Amazon): from search listing
- rcdrone.top: OVONIC 1S 850 mAh specs: 3.8 V LiHV, 100C, 14–17.5 g
- Oscar Liang: BetaFPV Air75 review: 1S LiHV packs on the Air75
- IntoFPV: BetaFPV Air75 thread: BetaFPV recommends 450 mAh; BT2.0 packs
- Betaflight releases: switchable battery profiles in 2026.6