Components
LiPo batteries for FPV
The battery is the last part a build needs and the first part that visibly wears out: what the S count, capacity, C rating and connector on the label actually control, and what they don't.
Every other part of a build gets chosen once and mostly stops changing: a frame stays bolted together, a stack stays flashed and tuned. The battery is the exception. It is bought in batches, it is cycled every flight, and it is the first component to age out from under a build that otherwise still works. It is also the last thing in the chain the motor and ESC guide describes: KV needs a cell count before it means anything, and the pack is where that cell count is actually decided.
How a pack is described
A LiPo pack's label carries four numbers that matter, and they answer four different questions.
- Cell count (S)Cells wired in series; nominal voltage is S × 3.7 V, full charge is S × 4.2 V, so a 6S pack is nominally 22.2 V and tops out at 25.2 V
- Capacity (mAh)Charge the pack holds; sets how long a given current draw can be sustained before the pack is empty
- C ratingThe manufacturer's claimed multiplier of capacity for maximum continuous discharge current
- ConnectorThe physical current path between pack and ESC; sized to what the pack is expected to deliver, not to what fits in the hand
None of these four numbers is optional and none of them is interchangeable with another. A pack with plenty of capacity but an undersized connector is still current-limited at the plug. A pack with a huge claimed C rating but the wrong cell count for the motors it is plugged into is still the wrong pack.
Cell count follows the motor, not the other way round
It is tempting to shop for a battery on its own: pick the highest capacity that fits, in whatever cell count is cheapest that week. That gets the order backwards. A motor's KV is only meaningful next to a cell count, because KV times pack voltage sets the motor's target RPM, and that target is what the motor, ESC and prop were all sized around. A pack bought for its capacity or its price, in a cell count the motors were not wound for, either underspins the motors on too few cells or overspins and overheats them on too many.
In practice this means cell count is not a battery decision at all. It is decided earlier, when the motor's recommended KV range is matched to a voltage, exactly as the motors and ESCs guide covers. By the time a builder is choosing a specific pack, the S count is already fixed; what is left to choose is capacity, C rating and connector within that constraint.
C rating: the most inflated number in the hobby
The mechanism behind a C rating is simple arithmetic: C multiplied by capacity, expressed in amp-hours, gives a nominal maximum continuous discharge current. A 1500 mAh pack (1.5 Ah) printed with a 75C rating is claiming 112.5 A continuous. On paper that is a precise, checkable figure.
In practice it is close to unverifiable from the label. There is no shared, disclosed test standard behind most consumer C ratings: no published test current, duration, temperature or cutoff voltage a buyer can check the number against, and no requirement that a manufacturer test the batch being sold rather than a rating applied to the whole product line. Two packs printed with the same C rating from two different brands are not necessarily tested the same way, or tested at all. Treat the printed number as a marketing figure the pack is sold under, not a measured spec the pack is guaranteed to meet.
What a C rating cannot hide is voltage sag: the pack's voltage dropping under load as current increases. Sag is driven by the pack's internal resistance, which rises with cell wear and is not printed on any label, and it is the one thing a builder actually feels in the air, as a punch-out that goes soft or a pack that reads lower on the OSD the harder it is pushed. A pack that sags heavily at full throttle is telling a builder more about its real discharge capability than the C rating on its wrap ever will. This page has not bench-tested any pack and makes no claim about a specific brand overstating its rating; the point is structural, not a result.
Capacity against weight
More capacity means more flight time, but it also means more weight, and more weight means more thrust is spent just holding the extra battery up before any of it goes toward endurance. Past a certain pack size for a given frame and motor combination, the added mAh buys back less flight time per gram than the pack before it did, because a growing share of the added capacity is paying for the mass of the added capacity itself. Taken far enough, a builder is carrying battery to fly the battery rather than to fly the aircraft.
Where that point sits depends on the specific motors, prop and airframe, not on a rule that applies across builds, which is why it is worth working through with the flight time calculator for a specific setup rather than guessing from a pack's capacity number alone.
Connectors: a current decision, not a preference
XT30, XT60 and XT90 look like a size preference, but they describe how much current the plug and its wiring are built to carry before the contact itself becomes the weak point in the circuit. A high-C pack pushed through an undersized connector does not get a free pass because the cells could theoretically deliver more: resistive heating at an overloaded contact happens at the plug regardless of what the pack behind it is rated for, and it happens faster than most other failure points in the power path. Matching connector to pack, not to whatever plug happens to be on hand, is part of sizing the battery, not a cosmetic choice after the fact.
| Build class | Typical cell count | Typical capacity | Typical connector |
|---|---|---|---|
| Tiny whoop / micro (under 100 g) | 1S–2S | 300–450 mAh | PH2.0 or BT2.0 |
| 3" | 3S–4S | 450–850 mAh | XT30 |
| 5" freestyle / race | 4S–6S | 1300–1500 mAh | XT30 or XT60 |
| 7" long range | 6S | 1300–2200 mAh | XT60 |
| Heavy lift / cinelifter | 6S–12S | 3000 mAh and up | XT90 or larger |
Storage voltage: why a full pack loses capacity
A LiPo cell is chemically most stressed at the two ends of its range: fully charged at 4.2 V and fully empty near 3.0 V. Left sitting at 4.2 V per cell for days or weeks rather than flown soon after charging, a pack degrades faster than one left at a partial charge, which is why chargers with a "storage" mode target roughly 3.8 to 3.85 V per cell rather than full or empty. The practical habit that follows is straightforward: charge to storage voltage for a pack that will not fly within the next day or two, and only bring it to a full charge shortly before the session it is actually used in.
Cycle life: not a number a label can promise
There is no fixed cycle count a LiPo pack is guaranteed to deliver, and this page will not print one. How many cycles a pack actually gets depends on how it is charged, how hard it is discharged, how hot it runs in the air, and how it is stored between flights, and those four factors interact rather than adding up neatly. Two packs bought on the same day, one charged gently and stored at storage voltage and one charged fast and left full between flights, will not age at the same rate. A capacity check against a fresh pack of the same model is a better indicator of where a given pack stands than any number printed on its wrap when it was new.
Puffing: the visible end of life
Puffing is a pack's pouch swelling as gas builds up inside from breakdown of the electrolyte. It is the one failure mode of a LiPo pack a builder can actually see and feel: a puffed cell no longer sits flat, and pressed gently it does not spring back the way a healthy pack does. It can result from age, from routine over-discharge, from a hard crash that damaged a cell internally, or from being left at full charge for too long, and by the time it is visible the internal damage is already done regardless of the cause. Puffing is not a fault a pack recovers from; it is the pack telling a builder it is finished.
Safe charging and transport
A safe default charge rate is 1C of the pack's stated capacity, applied regardless of what discharge C rating is printed on the wrap: charge and discharge C figures are not the same number, are not tested the same way, and a charger set to a conservative default does not depend on trusting either one.
Safety
LiPo packs are a fire risk when damaged, overcharged or short-circuited. Charge and store packs in a fireproof container or dedicated LiPo bag, never leave a charging pack unattended, and never charge or transport a pack that is punctured, swollen or otherwise visibly damaged. A damaged or puffed pack is retired, not repaired.
The battery is where the rest of the build's choices become current in a wire: see the motors and ESCs guide for how cell count and KV are matched before a pack is ever bought, the frame guide for where that weight ends up sitting on the airframe, and the flight time calculator for turning a specific pack's capacity into a real endurance estimate. New to this entirely, start with the first build path, or step back to the components overview for the rest of the parts list.