LiPo Battery Packs and Chargers

Which numbers must match: volts, capacity and chemistry

Voltage is the number that must match. A single lithium-polymer or lithium-ion cell is usually rated at 3.7 V, so 7.4 V means two cells in series and 11.1 V means three, while nickel-based cells are 1.2 V or 1.6 V each. A pack of the wrong voltage can damage the device or fail to start it. Capacity is more forgiving: a higher milliamp-hour rating at the same voltage and size gives longer run time.

Chemistry matters beyond voltage. Lithium-polymer packs are light and can deliver high current, which suits RC models, but they need a matching charger and careful handling. Lithium-ion packs are common in remote controls and gadgets. Nickel-based packs are simpler to charge and handle but heavier for their capacity, although nickel-zinc cells need a charger made for that chemistry. Listings also give watt-hours, which equal volts times amp-hours and let you compare packs of different voltages fairly.

Fit, connectors and a charger for the chemistry

Replacement packs are sold by device model, so match the model or part number in the title and check the dimensions and the connector. A pack with the right voltage but a different plug, polarity or protection board may not work or may be unsafe. Many packs contain a protection circuit that cuts power on overcharge or short circuit; bare cells without protection are for builders who know what they are doing.

Charge with a charger made for the chemistry and cell count. Lithium-polymer packs with several cells should be charged on a balancing charger, on a non-flammable surface and never left charging unattended. Do not mix old and new packs or different capacities in one series set. Store lithium packs partly charged in a cool place, and keep them out of hot cars.

Questions about LiPo Battery Packs and Chargers

Can I use a higher-capacity battery than the original?

Usually yes, if the voltage, connector and physical size match. A higher milliamp-hour rating gives longer run time at the same voltage, while a lower one shortens it. Never change the voltage rating, and check the dimensions if the battery compartment is tight.

What is the difference between mAh and Wh?

Milliamp-hours measure charge capacity, and watt-hours measure energy. Watt-hours equal volts times amp-hours, so a 7.4 V pack of 2,600 mAh holds about 19 Wh. Use Wh to compare packs of different voltages, and mAh only between packs of the same voltage.

Is it safe to keep using a swollen battery?

No. Swelling means gas has formed inside the cell, and the pack can overheat or catch fire. Stop using it, do not charge or puncture it, and place it in a non-flammable container until you can take it to a battery recycling point.