RC Plane LiPo Battery Guide: Cells, C-Ratings and Safe Charging

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A LiPo pack is a fuel tank that can also start a fire if it is mistreated. That is not a reason to be scared of them, since modelers charge thousands of packs without incident. It is a reason to read the label, learn four numbers, and follow a short list of rules.

This page is built from manufacturer documents, official safety notices and maker product pages, checked in October 2026. It is not based on our own testing, so there are no pack "torture test" results here. Where sources disagree, the page says so, and the pack listings show stock status only, with no prices.

Start With the Plane's Own Specification

The right pack is the one the airframe's maker lists. That sounds obvious, but the sizes vary more than most roundups suggest. A sample from the makers covered in other guides on this site:

If you are choosing a first plane, the best RC trainer planes and best RC planes for beginners guides list what each model ships with and needs. For motor sizing, see the RC plane motors guide. For warbird and jet packs, the warbird guide and the EDF jet guide go through their own setups.

How to Read a LiPo Label

Cell count (S). Each LiPo cell is rated 3.7 volts nominal. The AMA Flight School lesson on LiPo safety says each cell requires a charging voltage of 4.20 volts, and not to let any cell drop below 3.2 volts. So 3S is 11.1V nominal, 4S is 14.8V, 6S is 22.2V and 12S is 44.4V. Cell count is not a tuning option: the ESC and motor are built for a voltage range, so match the maker's number.

Capacity (mAh). The fuel tank. More capacity means longer flights and more weight. Makers publish a range for each plane, as in the table above.

C-rating. The discharge multiplier. Continuous current is capacity in amp-hours times the C-rating:

• 2200mAh is 2.2 Ah. At 30C, that is 2.2 × 30 = 66 A.
• At 45C, the same pack is 2.2 × 45 = 99 A.

To work backwards, divide the motor and ESC draw by the pack capacity. A 50 A draw on a 2.2 Ah pack is 50 ÷ 2.2, about 22.7C, so a 30C pack covers it with margin. The number you want is the one that covers the draw, not the biggest figure on the label. Horizon describes how it checks packs: continuous discharge to 3.0V at a minimum percentage of the published C rating for 3 seconds, and a duty cycle discharge for 15 seconds. That is one maker's test method, and C-ratings from different brands are not guaranteed to mean the same thing.

Charge rate. Horizon's safety sheet says not to charge faster than 1C unless the maker specifies otherwise. For a 2200mAh pack, 1C is 2.2 A, which matches the standard charge current on the Spektrum Smart G2 3S 2200mAh listing. Gens ace says 1-3C is recommended on its G-Tech packs, which is the maker's own allowance, so read the label on the pack in your hand.

Connectors

Mismatched connectors are the most avoidable problem in the hobby. What the makers say:

The XT numbers come from distributor spec tables, not an Amass datasheet, and the sources conflict, so treat the "60A" and "90A" figures as peaks. Horizon's safety sheet makes the broader point: preinstalled connectors have power limits, and a pack can produce more current than the connector can handle. If your setup exceeds the connector, replacing it is the user's responsibility.

Horizon's J-3 Cub and Cessna manuals use EC5 or IC5 connectors on large electrics, while its smaller models use EC3 or IC3, and Dynam specifies XT60 on its warbirds. Match the connector on the plane before you buy a pack, and re-solder carefully if you change it.

Charging Rules From the Makers

Horizon's Lithium Polymer Battery Safety Guidelines are the clearest primary source. The core rules:

• Never leave batteries charging or discharging unattended or overnight.
• Use a charger with a cell balancing mode designed for lithium batteries.
• Charge in a fireproof or fire-retardant container, such as a LiPo bag, in an open area away from flammable materials.
• Never charge batteries inside the model.
• Never charge a hot battery (above 100°F), and never charge below 40°F (4°C).
• Never charge wet batteries.
• Set the chemistry, cell count and voltage to match the label.
• Do not charge faster than 1C unless the maker says otherwise.
• Check voltage before each charge. If it is below the recommended starting level, the battery was over-discharged and should not be charged.
• Match the balance lead to the correct port, and on a multi-port charger use the same channel for the power and balance leads.

The AMA Flight School lesson adds: use a charger designed for LiPo batteries, and always verify settings for cell count and charge rate. Horizon's guidance on cells that have sat unused: batteries out of service for more than six months need a voltage check, and each cell should be at least 3V before charging.

Chargers

SkyRC iMAX B6AC V2

The B6AC V2 is a common first balance charger, and SkyRC's own page lists the specifics: AC input 100-240V and DC input 11-18V, maximum charge power 50W, charge current 0.1-6.0A, discharge current 0.1-2.0A (5W maximum), LiPo, LiFe and Li-ion packs in 1-6S, and NiMH or NiCd in 1-15S. It supports a LiHV mode for 4.35 V end of charge, a storage mode, balance sockets for 2-6S, and PC connection for firmware updates. SkyRC says the V2 adds automatic charging current limit, capacity limit, temperature threshold and time limit compared with the first version, and can serve as a lithium battery meter and internal resistance meter. The box includes leads with XT60, banana, alligator, Futaba and JST connectors.

Search for the SkyRC iMAX B6AC V2 on Amazon

Spektrum Smart chargers

If you fly Horizon BNF planes, a Smart charger recognizes Smart pack data and sets itself up. The Spektrum S155 55W AC G2 Smart Charger is in stock and charges 4S LiPo, LiFe, Li-ion and LiHV packs as well as 1-12S NiMH and NiCd, with IC3 and IC5 ports. It charges and balances Smart G2 packs over one connection, has a color LCD, and takes firmware updates over USB. The older S150 is discontinued.

Search for the Spektrum S155 Smart charger on Amazon

Chargers to avoid: CPSC notices

The U.S. Consumer Product Safety Commission has acted on two HTRC charger models:

The T400 is black with a touch screen and "T400" on the front, and some units show "HTRC" while others show no brand. The C240 DUO has two blue screens numbered 1 and 2, with "C240 DUO" between them. The C150 and T150 were not named in the notices read for this guide. If you own a named model, stop using it and follow the CPSC instructions.

Storage and Care

Horizon's safety sheet and the E-flite manuals agree on the essentials:

• Store at about half capacity. Horizon says "approximately 1/2 of the capacity listed on the Batteries' label, or 3.8V per cell". E-flite's Cessna 150T manual says to charge to about half capacity before storage.
• Smart G2 packs do it automatically. Horizon says they come programmed to discharge to a safe storage voltage of 3.90V after 72 hours of inactivity, and that setting can be changed.
• Keep them cool. Storage temperature 40-120°F (4-49°C), never in a full-sized vehicle or in direct sunlight.
• Disconnect after use. E-flite says to remove the battery from the aircraft after flying to prevent trickle discharge.
• Use the low-voltage cutoff. E-flite's manual explains the ESC pulses the motor when voltage gets low, because some power is reserved for flight control and landing. Land when the motor pulses.
• Store in a non-conductive, fireproof container, and never keep loose packs together where terminals can touch.

Packs Listed by Makers

Stock status below was checked on maker or distributor shop pages in October 2026.

Spektrum Smart G2

Horizon says G2 balancing information travels through the data wire, so no separate balance lead is needed, and the 30C soft-case packs have thicker internal metal side plates to improve heat dissipation and puncture protection. The first-generation 3S 2200mAh 30C Smart pack is out of stock and the 100C version is discontinued.

Search for Spektrum Smart G2 3S 2200mAh batteries on Amazon

Gens ace

Gens ace's European shop lists these G-Tech packs in stock:

Gens ace says its packs fulfill ISO9001 and ISO14001 standards. US-market variants such as Deans-connector 3S packs were not found on the European shop, so check your own retailer for connector and stock.

Search for Gens ace 3S 2200mAh 45C LiPo on Amazon

Ovonic

Ovonic's shop lists a 2-pack of 11.1V 2200mAh 3S 50C packs with XT60 in stock, which Ovonic describes as a reliable choice for 1100mm-1500mm RC planes. Several of its high-C 3S and 4S 2200mAh packs, including the 4S 120C XT60 pack, show as unavailable. High C-ratings on small packs are marketed for FPV and car use, so match the pack to your plane's draw rather than the headline figure.

Search for Ovonic 3S 2200mAh 50C LiPo on Amazon

When Things Go Wrong

After a crash. Horizon says to disconnect and remove the battery from the model quickly and safely, then watch it in a safe place for 10-15 minutes before using it again.

Swollen or damaged packs. Horizon says damaged or swollen batteries can be unstable and very hot, and not to touch them until they have cooled. Discontinue use and dispose of them. The AMA Flight School lesson says to skip discharging a ballooned pack and submerge it in salt water, and to place dead or damaged batteries in a covered container of salt water for 2 weeks before disposal. The lesson does not address extinguishers.

Fire. Horizon's wording is to call emergency services immediately, because only a Class D, dry chemical fire extinguisher must be used. Dave Gee's Model Aviation column offers a more nuanced view: an extinguisher fights the flames, but cooling the pack can keep other cells from igniting in a chain reaction, sand can help, but burying a hot pack can insulate it, and experts do not agree on every detail. He also notes that, statistically, aeromodeling LiPos are safe and reliable, and calls a charging pot or bag cheap insurance.

Fire bags. Horizon recommends charging in a LiPo bag or other fireproof container; a bag limits damage and is not permission to leave a charging pack.

Recycling. Call2Recycle is the usual U.S. collection program. Healthy lithium packs are generally accepted at drop-off sites, while damaged, defective or recalled batteries need special handling and cannot go in regular boxes. Confirm current rules with the program.

Picking a Pack: A Short Decision Table

FAQ