RC Battery & Power System Guides — LiPo, Connectors, ESCs & Chargers

The C-rating is a multiplier on capacity that estimates maximum continuous discharge current. A 5000mAh 60C pack, for example, is rated for roughly 300A continuous (5Ah x 60). Real-world safe current is usually lower once wire gauge and connector limits are factored in.

XT60 handles roughly 60A continuous and suits most 2S-4S packs under moderate load. XT90 is built for higher continuous current, generally 90A and up, and is the safer choice for high-C 4S-6S packs feeding power-hungry brushless systems.

A basic charger without balance leads can bring the pack up in overall voltage, but it can't correct for individual cell imbalance, which is the main safety mechanism that prevents overcharging a single cell. It's a stopgap, not a routine method.

Swelling usually means gas has built up inside the cells from overcharging, over-discharging, physical damage or age-related breakdown of the internal chemistry. A puffed pack has reduced capacity and a higher failure risk and should be retired rather than depuffed and returned to regular use.

Most manufacturers recommend storing LiPo packs around 3.8V per cell (a 3S pack at roughly 11.4V total) rather than fully charged, since holding a pack at full charge for weeks accelerates capacity loss.

A charger that won't recognize a pack is often reading a cell voltage outside its safe range, a damaged balance connector, or a charger set to the wrong cell count or chemistry. Checking individual cell voltages with a separate meter usually narrows down which of the three it is.

Blink patterns vary by brand, but a repeating red blink most often signals a low-voltage cutoff, a throttle calibration issue, or a lost signal from the receiver. Checking the manual's specific blink-count table is more reliable than guessing from a general rule.

It can work on NiMH packs that have developed internal dendrites or a specific type of cell short, but it's not effective on LiPo chemistry and isn't a permanent fix even on NiMH. It buys a pack a limited number of additional cycles at reduced capacity.

Check that the ESC's continuous and burst amp ratings exceed what the motor will actually draw under load, that its voltage range covers your cell count, and that its BEC output can support the receiver and any servos wired to it.

XT30 is smaller and lighter, suited to 1S-2S packs under roughly 30A, while XT60 is larger, rated for around 60A continuous, and is the more common choice once a build moves to 3S or higher.