LiPo 2S Battery 101: All About LiPo 2S Batteries

Lithium Polymer batteries, also known as LiPo or Lipo batteries are a special type of rechargeable lithium batteries that feature electrolytes in the form of polymer gel, and in their basic form, they are soft to touch.

LiPo 2S batteries feature two LiPo batteries connected in series in order to provide larger voltage, commonly 7.4V. As such, they are commonly used as sources of strong currents in various applications, including RC cars, RC boats, RC trucks, and other toys, but also applications like robotics and similar.

Updated: November 21, 2024.

LiPo 2S Batteries Features and Specifications

LiPo 2S batteries consist of two (2) lithium polymer cells connected in series (hence the "S") in the so-called 2S1P configuration.

Most of the LiPo cells used to create LiPo 2S batteries feature a nominal voltage of 3.7 volts, a maximum charging voltage of 4.2 volts, and a minimum voltage of 3.2 volts.

2S LiPo Battery Voltage

A 2S LiPo battery consists of two cells connected in series, resulting in specific voltage characteristics that are important for its operation and longevity. The nominal voltage of a 2S LiPo battery is 7.4V (3.7V per cell). This is the average voltage during discharge and serves as a key parameter for selecting compatible devices and chargers.

When fully charged, a 2S LiPo battery reaches a voltage of 8.4V (4.2V per cell). This is the maximum safe voltage for standard 2S LiPo batteries, and exceeding this value can lead to overcharging, potentially causing damage or safety risks. It is essential to use a LiPo-specific charger that can correctly regulate the charging process and prevent overcharging.

On the lower end, the lowest safe discharge voltage for a 2S LiPo battery is 6.0-6.4V (3.0-3.2V per cell). Discharging below this threshold can permanently damage the battery, reducing its capacity and lifespan. Many devices equipped with 2S LiPo batteries include voltage cutoff settings to prevent over-discharging, ensuring the battery's long-term performance.

Understanding these voltage ranges is vital for maintaining the health of a 2S LiPo battery. Proper charging, storage, and usage within the specified voltage limits not only enhance performance but also ensure safety and reliability in applications such as RC vehicles, drones, and portable electronics.

Note: these are the most common values - it is important to check the specs of each battery model before charging and use.

High-Voltage 2S LiPo Batteries

High-voltage (HV) 2S LiPo batteries are an advanced version of standard lithium polymer batteries, offering increased energy density and performance. While a standard 2S LiPo battery has a nominal voltage of 7.4V (3.7V per cell), high-voltage variants have a nominal voltage of 7.6V (3.8V per cell).

This slight increase in nominal voltage can significantly improve performance in applications requiring higher power outputs, such as RC vehicles, drones, and other high-demand electronics.

The voltage characteristics of high-voltage 2S LiPo batteries differ from standard models. When fully charged, a standard 2S LiPo battery reaches 8.4V (4.2V per cell), while a high-voltage 2S LiPo can safely charge up to 8.7V (4.35V per cell).

This allows for greater capacity and longer run times without increasing the physical size of the battery. However, it is essential to use a charger specifically designed for high-voltage LiPo batteries to avoid overcharging, which could damage the cells or cause safety issues.

The lowest discharge voltage also varies between the two types. For standard 2S LiPo batteries, the lowest safe discharge voltage is 6.0V (3.0V per cell), whereas high-voltage 2S LiPos can be safely discharged down to 6.6V (3.3V per cell). Exceeding these limits can lead to irreversible damage, reduced lifespan, or even safety hazards.

High-voltage 2S LiPo batteries are especially beneficial in scenarios where every bit of extra power matters. The trade-off for this improved performance is that they require more precise handling, charging, and storage to maintain their efficiency and safety.

Adhering to manufacturer guidelines and using compatible equipment helps the user take full advantage of the enhanced capabilities these batteries offer.

2S LiPo Battery Capacity

2S LiPo battery capacities vary from a few hundred mAh to large 10+ Ah batteries used in most energy-hungry toys, RC vehicles, and applications.

Output currents usually vary between 25 and 100C, although there are some models that are able to provide even stronger burst currents, although for a very short time.

On the other hand, 2S LiPo batteries should be charged with 0.5-1.0C currents - when compared with the discharge currents, charge currents are relatively low, but when compared with older types of batteries, 2S LiPo batteries can be recharged rather quickly.

When charging the LiPo batteries, it is highly recommended to use balance LiPo chargers that charge and monitor each cell individually.

Versatile and Reliable Haisito Smart Balance Charger (LiPo, Li-ion, Li-Fe, NiCd, NiMH) (Amazon link, opens in the new window)

This is very important for 2S batteries, but even more important for LiPo batteries with more cells connected in series - LiPo batteries are sensitive to overcharging and if the end voltage is 8.4V for a battery pack, it is very desirable that both cells are at 4.2V.

On the other hand, charging one cell to 4.0V and another to 4.4V (just an example), can lead to battery overheating or even bursting into flames...

That is why LiPo batteries are never left unattended when being charged, even if they are charged using balance chargers - better safe than sorry.

2S LiPo Battery Connectors

2S LiPo batteries come with two sets of cables, including:

• discharging cables feature thick wires in order to keep the energy losses as low as possible. Also, they very often feature Dean T connectors, which are almost standard for 2S LiPo batteries intended for low to moderate currents.
• charging cables are much thinner than discharging cables and they usually feature JST-XH or some very similar plug. Such plugs allow the charger to monitor, balance, charge and even discharge each cell individually.

Note: In the case of ordering/receiving the battery (or batteries) with wrong plugs, there are many adapters on the market that allow the user to connect the battery with "wrong" plugs into the device/charger that has different connectors.

Of course, each connection adds some resistance, slightly increasing the energy losses, and should be avoided if possible.

Storing and Transporting 2S LiPo Batteries

Due to LiPo batteries' great sensitivity to overcharging and over-discharging conditions, they have a tendency to overheat or even burst into flames or to explode if pushed over their limits.

In order to avoid such events and to use them as safely as possible, when the new battery (or batteries) arrives, be sure to read its instructions, especially charging, storage, and safety issues/procedures.

When charging, storing, and transporting all LiPo batteries, not just 2S LiPo batteries, it is highly recommended to use fireproof bags.

Very popular, affordable, but tough and durable: Zeee Fireproof and Explosion-proof LiPo Battery Bag (Amazon affiliate link, opens in the new window)

Of course, such fireproof bags are not absolutely required, but better safe than sorry.

2S LiPo Batteries Charging/Discharging Cycles

2S LiPo batteries support several hundred charging/discharging cycles, but this depends on the battery quality, discharge currents, charging currents, cell balancing, quality of battery charger, use and storage temperature, and similar.

Also, although not emphasized by many brands, when the new battery arrives, it is a good practice to make a few test charging/discharging cycles, with a gradual increase in Depth of Discharge. For example:

• charge the battery to 100% and discharge it slowly to 25% DoD,
• charge the battery to 100% and discharge it slowly to 50% DoD,
• charge the battery to 100% and discharge it slowly to 75% DoD,
• charge the battery to 100% and discharge it slowly to 90-95% DoD.

After each charging and discharging, be sure to let the battery cool down.

Personally, there is no need to push the battery down to 100% DoD right away.

How Long Does a 2S LiPo Battery Typically Last?

The lifespan of a 2S LiPo battery depends on several factors, including its quality, usage patterns, and maintenance practices. Typically, a well-maintained 2S LiPo battery can last for 300 to 500 charge cycles, which translates to about 1 to 3 years of regular use. However, this estimate can vary based on how the battery is used and cared for.

Key factors influencing the lifespan include:

• Discharge Depth: Regularly discharging a 2S LiPo battery below its safe limit of 6.0V (3.0V per cell) can significantly reduce its lifespan. To prolong battery life, it's recommended to avoid deep discharges and instead keep the battery above 20-30% charge whenever possible.
• Charging Practices: Using a compatible charger and adhering to the maximum voltage of 8.4V (4.2V per cell) for standard batteries ensures safety and longevity. Overcharging or using improper charging settings can damage the cells.
• Storage Conditions: Storing a 2S LiPo battery at storage voltage (7.6-7.8V) and keeping it in a cool, dry environment can prevent cell degradation. Avoid storing it fully charged or completely discharged for extended periods.
• Usage Environment: Operating the battery within its recommended temperature range helps prevent damage. Extreme heat or cold can strain the cells, shortening their lifespan.

Long Story Short: 2S LiPo batteries are a very popular battery type and are used from small RC toys to larger RC trucks and other applications.

When looking for a new 2S LiPo battery (Amazon link, opens in the new window), always check actual dimensions, capacity, current rate, and connectors and choose according to your own personal needs and requirements.

And whatever You do, stay safe - it is, after all, your own responsibility.