Your drone's battery is the most expensive part you'll keep replacing. It's also the part most likely to cause a problem if it's mistreated.
Look after it, and it'll last for hundreds of flights. Here's how.
What kind of battery is it?
Almost every drone uses lithium batteries. Most use LiPo (lithium polymer). Some newer drones use Li-ion cells. Both pack a lot of energy into a small space. That's why they need care.
A battery is made of cells. Each LiPo cell is nominally 3.7 volts.
- Fully charged: about 4.2V per cell. (Some high-voltage packs, marked LiHV, go to 4.35V.)
- Storage charge: about 3.8V per cell.
- Empty: you should land well before 3.5V per cell under load.
A "3S" battery has three cells. A "4S" has four. And so on.
Charging safely
- Use the right charger. Use the drone's own charger, or a proper balance charger set to the right battery type.
- Never leave a charging battery alone. Stay in the room.
- Charge on a hard, non-flammable surface. Not on a bed, sofa or carpet.
- Use a LiPo safe bag or a metal box for extra peace of mind. They're cheap.
- Let it cool first. A battery fresh from a flight is warm. Give it 15 to 20 minutes before charging.
- Don't charge a damaged battery. If it's puffy, dented or the wires are damaged, stop.
Storage: the most important habit
LiPo batteries hate sitting full. Leaving them at 100% for days wears them out fast.
Store them at around 3.8V per cell. This is called storage charge. Most good chargers have a storage mode. Many DJI-style smart batteries discharge themselves to storage level after a set number of days.
If you're not flying for more than a day or two, put your batteries on storage charge.
Store them:
- somewhere cool and dry
- away from direct sunlight
- in a fireproof bag or box
- away from anything flammable
Cold weather
Batteries hate the cold. In winter you'll get noticeably shorter flights. The voltage can also sag suddenly under load.
- Keep batteries warm in an inside pocket until you fly.
- Hover for 30 seconds after take-off to warm them up.
- Land earlier than you would in summer.
How far to fly them down
Running a battery flat shortens its life and can damage it. It's also the most common cause of a drone falling out of the sky.
Land with at least 20 to 30% left. Set your low battery warning to match.
On FPV quads, keep an eye on the voltage. Landing at around 3.5V per cell (resting) is a good habit.
Swelling (puffing)
A puffy battery is a damaged battery. It happens through age, over-discharge, overcharging or a crash.
If a battery has swollen:
- stop using it
- don't charge it
- don't puncture it
- dispose of it safely
Don't squeeze it back into the drone. A puffed battery can fail in flight, or catch fire.
After a crash
Check the battery straight away. Look for dents, splits or a hot spot. Put it somewhere safe, outside if possible, and watch it for 30 minutes before you put it back in your bag.
Travelling with batteries
- Carry batteries in your hand luggage on flights, never in checked bags.
- Airlines usually allow batteries up to 100Wh without approval. Between 100Wh and 160Wh needs airline approval. Check with your airline.
- Tape over exposed contacts, or use the covers that came with them.
- Travel at storage charge.
Disposing of old batteries
Don't put LiPo batteries in the bin. Take them to a battery recycling point. Many supermarkets and recycling centres have one.
Discharge them first if your charger can do it safely.
Quick rules
- Never charge unattended.
- Store at 3.8V per cell.
- Land with 20 to 30% left.
- Retire any battery that puffs up.
- Keep them warm in winter and cool in summer.