- RGB Critter BTThe app-controlled flashlight.
- Flow Art KitsSwap heads. Keep the light.
- Light Painting ToolsSwap mods. Shape the light.
- Flow Art AccessoriesGrab spares. Keep it spinning.
Your 18650 cell, explained
One replaceable 18650 cell, charged inside the light.
Use the right cell, charge it in the Critter and store it sensibly, and it will look after you for years. The official replacement is the same cell that ships in every Critter BT.
The right battery
The Critter is built around one exact cell. A different size or type can stop it working, or damage the electronics for good.
- Format18650 lithium-ion
- Size18.4 x 65 mm (0.72 x 2.56 in)
- Positive endFlat top, no raised button
- ProtectionUnprotected (protected cells are longer)
- Voltage3.6 V nominal, 4.2 V full
- Capacity2500 mAh or more
- Run timeUp to 7 hours
- DischargeHigh-drain, 30 A continuous

Official replacement cell
Fits every CritterThe same 2500 mAh cell that ships in every Critter BT, ready to swap in seconds. Up to 7 hours of run time, about 2 on full white.
US addresses only. Shipping rules stop us sending spare cells abroad or by overnight service. Outside the US, buy one locally to this spec.
Buying a cell locally
Get any of these wrong and the cell may not fit, or may damage the light. Check them before you buy.
Look for
- 18650, flat top, unprotected, 3.6 or 3.7 V
- A high-drain cell from a well-known maker. Any real capacity works; higher just runs longer.
- A specialist battery shop, not an anonymous marketplace seller
- An intact wrap with no dents, tears or bare metal
Avoid
- Protected cells, a few mm longer than the Critter is built for
- Button-top cells, also too long
- 3.2 V LiFePO4 or 1.5 V lithium cells, the wrong voltage
- "Fire" style brands claiming 6000 to 9900 mAh, which no real 18650 delivers
Everyday care
Four habits that keep a cell healthy for years.
Charge
- Inside the Critter, over USB‑C, with the included cable
- From a plain USB-A adapter, 1.5 A or more. Fast-charge (USB-PD) bricks may not power it.
- Pulsing red means charging. Blinking red means a bad USB source.
- At room temperature, somewhere you can see it
Store
- Hold Power for 1 second to sleep. A quick tap is standby and keeps draining.
- Away 2 to 3 weeks or more? Take the cell out and leave it about half charged.
- Cool and dry, never in a hot car
Travel
- Spare cells go in carry-on only, never checked bags
- Cover the ends: a case, tape, or one cell per bag
- Never loose with keys or coins
- About 9 Wh, far under the 100 Wh airline limit
Retire it
- Any dent, torn wrap or bare metal
- Ran unusually hot while charging or in use
- Drains on its own, or run time has collapsed
- Recycle at a battery drop‑off, never household trash
If a cell gets hot, hisses or swells
- Stop using it and unplug the charger right away.
- Move it outside or onto a non-flammable surface, away from anything that can burn.
- If it catches fire, douse it with plenty of water. Don't try to hold it.
- Never charge or use that cell again.
Keep learning
Deeper reading, plus the parts that go with the battery.
Lithium-ion cells can catch fire or burst if they are damaged, mishandled or used outside the manufacturer's ratings. Please read and follow the guidance above. Ants on a Melon is not responsible for injury or damage caused by misuse or mishandling of rechargeable batteries, or by cells other than the one supplied with your Critter.

