LiPo vs NiMH, Cell Count & C-Rating Explained

The label on an RC battery is packed with numbers that all mean something. Decode them once and you will never buy the wrong pack again.

LiPo vs NiMH — the two chemistries. NiMH (Nickel-Metal Hydride) packs are cheap, durable, and very forgiving — hard to hurt, safe to store charged, and a great match for a first brushed rig. They are heavier and hold less energy for their size. LiPo (Lithium Polymer) packs are lighter, punchier, and hold more energy, which is why racers and brushless rigs run them — but they demand careful charging and storage (read our LiPo safety guide before you run one).

Cell count: what "2S / 3S / 4S" means. The S is the number of cells wired in series. Each LiPo cell is nominally 3.7V (and tops out at 4.2V fully charged). So:

- 2S = 2 cells = 7.4V nominal (8.4V full)
- 3S = 3 cells = 11.1V nominal (12.6V full)
- 4S = 4 cells = 14.8V nominal (16.8V full)

More cells means more voltage, which means more speed and power — but only if your ESC and motor are rated for it. Check your ESC's cell range before going up. Feeding a 2S ESC a 3S pack is how you release the magic smoke. (NiMH packs are labeled by cell too — a common 6-cell NiMH stick is about 7.2V nominal, close to a 2S LiPo.)

mAh: how big the tank is. Milliamp-hours (mAh) is capacity — how much charge the pack holds. A 5000mAh pack holds more than a 3000mAh pack of the same voltage and will run longer, but it is bigger and heavier. Match the physical size of the pack to your rig's battery tray, then get the most capacity that fits.

C rating: how fast it can pour. The C rating is how hard the pack can discharge without overheating. Multiply the C rating by the capacity (in amp-hours) to get the safe continuous current draw. Example: a 5000mAh (5.0Ah) 50C pack can deliver roughly 5.0 x 50 = 250 amps continuous. A higher C rating handles a hungrier brushless motor without sagging or getting hot. A hot pack after a run is a sign the C rating is too low for how you are pushing it. Be a little skeptical of huge advertised C numbers on bargain packs — reputable brands rate honestly.

Connectors — match them or adapt them. The pack and the ESC have to use the same plug, or you need an adapter. The common ones you will meet:

- Deans / T-plug — small, low-resistance, very common on smaller rigs.
- XT60 — a robust yellow bullet connector, the default on a lot of modern rigs.
- XT90 / EC5 — bigger connectors for high-current 4S+ setups.
- Tamiya — the old white/blocky connector, still seen on cheap NiMH packs; high resistance, usually the first thing people upgrade.

Never force a mismatched connector or reverse the polarity — reversing a battery can instantly kill an ESC. When in doubt, solder on a matching connector or use a proper adapter lead.

Quick rule of thumb: match the cell count to your ESC's rating, get the highest mAh that fits the tray, pick a C rating high enough that the pack stays cool, and make sure the connector matches. Do that and the pack will run cool, last longer, and give you the run time you paid for.