LiPo Batteries for RC Modelling: How to Choose and Use Them Properly

When choosing a LiPo battery for RC modelling, I recommend first checking the voltage supported by your motor and ESC, followed by the capacity, discharge current, dimensions and connector.

Once you have chosen the right battery, its lifespan mainly depends on three habits: proper charging, controlled discharging and storage at the correct voltage.

Key Points

• The number of cells, indicated by the letter S, must match the motor and ESC: a 3S LiPo is not interchangeable with a 2S or 4S battery.

• Capacity in mAh affects runtime, but also weight and size. Bigger does not automatically mean better.

• The C rating helps estimate the current the battery can deliver. However, I recommend not relying on this figure alone when comparing different brands.

• To preserve your LiPo battery, charge it with a suitable charger, avoid deep discharge and use Storage mode, at around 3.8 V per cell, when it is not being used.

How Do You Choose a LiPo Battery for Your RC Model?

The right LiPo battery is one that simultaneously meets the electrical, mechanical and physical requirements of your model.

I always start with the model's instruction manual.

This should determine the number of cells, the recommended capacity and, where this information is available, the required current.

A battery may have the correct capacity and connector while being completely unsuitable for your power system.

This is particularly the case if you use a LiPo battery with too high a voltage.

When making your choice, I recommend checking the following in this order:

1. number of cells;

2. voltage supported by the motor and ESC;

3. capacity in mAh;

4. maximum current required;

5. C discharge rating;

6. dimensions;

7. weight;

8. connector;

9. balance connector.

This method may seem simple.

However, it prevents many of the mistakes that occur when choosing a battery based solely on its price or capacity.

What Voltage Should You Choose Between a 2S, 3S, 4S and 6S LiPo?

A 2S LiPo provides a nominal voltage of 7.4 V, a 3S LiPo 11.1 V, a 4S LiPo 14.8 V and a 6S LiPo 22.2 V.

The number before the “S” corresponds to the number of cells connected in series.

Each LiPo cell has a nominal voltage of approximately 3.7 V and reaches 4.2 V when fully charged.

Here are the key figures to keep in mind:

These figures highlight an important point: a 4S LiPo is not simply a 3S battery with slightly more runtime.

It supplies a higher voltage to the entire power system.

If your motor and ESC are designed for 4S, I would therefore not switch to a 6S LiPo without checking their compatibility.

The motor, ESC, cooling system and, on an RC car, the drivetrain must all be able to handle this voltage.

Scientific MHD also recommends always checking the model's technical specifications before choosing the number of cells.

How Do You Choose the Capacity in mAh?

Capacity, expressed in mAh, mainly affects runtime, battery weight and size.

A 5,000 mAh LiPo stores more charge than a 2,200 mAh battery.

It can therefore provide a longer operating time at a comparable level of power consumption. However, it will generally be heavier and larger.

This is particularly important with an RC aircraft.

On a lightweight model, a few hundred additional grams can affect the centre of gravity, wing loading and flight behaviour.

I therefore prefer choosing a capacity that suits the model rather than automatically looking for the largest battery that will fit inside the fuselage.

Scientific MHD's LiPo range currently includes, for example, Black Lithium batteries with capacities of 2,200 mAh, 3,300 mAh, 5,000 mAh, 6,000 mAh and more, with different cell configurations.

Does a Battery with More mAh Always Provide More Runtime?

No, not necessarily.

Runtime depends on capacity, but also on the actual current drawn by your motor.

Consider two batteries with the same voltage. A 5,000 mAh battery can theoretically provide more energy than a 3,000 mAh battery, but if it significantly increases the model's weight, the motor will also have to work harder.

I therefore look for a compromise: sufficient capacity + reasonable weight + compatible dimensions.

For an aircraft, I also check the centre of gravity. A heavier battery can sometimes be useful if it helps position the centre of gravity correctly.

This is not a general rule, but it is a parameter that is often overlooked.

How Do You Choose the C Discharge Rating?

The C rating indicates a battery's theoretical ability to deliver a high current relative to its capacity.

The basic calculation is simple:

theoretical current = capacity in Ah × C rating

Take a 2,200 mAh LiPo, or 2.2 Ah, rated at 25C:

2.2 × 25 = 55 A

The battery is therefore rated for a theoretical current of 55 A under the conditions corresponding to this specification.

Scientific MHD also uses this example to explain the principle of the C rating.

Should You Choose Exactly the C Rating Required by the Motor?

I prefer to keep some margin rather than continuously operating a battery at its theoretical limit.

You should also be cautious when comparing different brands.

A 50C rating displayed on one battery does not necessarily mean that it will actually deliver twice as much current as a battery rated at 25C under all conditions.

Internal resistance, temperature, ageing and the way the manufacturer measures or defines its C rating also play a role.

Industry specialists point out that C ratings are not always directly comparable between manufacturers.

I therefore consider the C rating to be one indicator among several, rather than the only measure of quality.

Why Is the Internal Resistance of a LiPo Battery Important?

Internal resistance provides an indication of the battery's ability to deliver current without causing a significant voltage drop.

Internal resistance that increases with age and use can result in greater “voltage sag”, meaning a drop in voltage when the motor demands a high current. The model may then feel less responsive even though the battery still accepts a charge.

I find this information particularly useful when the charger can measure the internal resistance of each individual cell.

You can also use a LiPo battery tester.

However, I would not compare two batteries solely on the basis of a value expressed in milliohms.

Capacity, technology, format and intended use also matter.

What Dimensions and Connector Should You Check?

A LiPo battery must not only be electrically compatible: it must also fit correctly inside the model and have suitable battery connectors.

Before ordering, measure the available space:

• length;

• width;

• height;

• maximum acceptable weight;

• cable position;

• main connector;

• balance connector.

Common connectors include XT30, XT60, XT90, Deans/T-Plug, EC3 and EC5.

The connector must be compatible with your setup. An adapter can solve certain situations, but it adds another connection.

For a setup designed to handle high current, I prefer a correctly sized, clean connection rather than a series of adapters.

Scientific MHD currently offers, for example, Black Lithium LiPo batteries fitted with XT60 connectors, as well as models with XT30 or Deans connectors depending on the product.

How Do You Choose a LiPo Battery for an RC Aircraft?

For an RC aircraft, I primarily look at voltage, weight, centre of gravity, capacity and the current required by the power system.

A common mistake is choosing a battery simply because it has enough mAh.

On a lightweight aircraft, a battery that is too heavy can negatively affect flight behaviour.

On a powerful model, a battery that is too weak can instead cause voltage sag, overheating and reduced performance.

I therefore recommend starting with the motor and ESC specifications and then checking the battery capacity recommended by the model manufacturer.

How Do You Choose a LiPo Battery for an RC Car?

For an RC car, current demand can be high, particularly with a brushless power system.

I therefore pay particular attention to:

• the maximum voltage supported by the ESC;

• the required current;

• the C rating;

• the dimensions of the battery compartment;

• the connector;

• the weight.

A car designed for a 2S LiPo should not be fitted with a 3S battery simply because the latter appears more powerful.

The ESC, motor and drivetrain must all be designed for this voltage.

For a competition car or a heavily used model, internal resistance and the battery's ability to maintain its voltage under high load also become important.

How Do You Choose a LiPo Battery for an RC Boat?

For an RC boat, I look for a balance between capacity, available current and weight.

Power consumption can be high with a fast motor setup. An undersized battery may therefore become very hot.

I also check the physical installation. The battery pack must be securely held in place and protected against water splashes.

The battery must not be able to move during acceleration or changes of direction.

How Do You Charge a LiPo Battery Correctly?

I always charge a LiPo battery with a charger designed for this technology, selecting the correct number of cells and charging mode.

A LiPo charger can monitor the voltage of each cell and, when equipped with a Balance mode, keep the cells at compatible voltage levels.

Scientific MHD recommends using a dedicated LiPo balance charger and points out that a cell must not exceed 4.2 V.

Why Do LiPo Cells Need to Be Balanced?

Balancing allows the charger to monitor the different cells in the pack and prevents one cell from reaching its maximum voltage before the others.

This is particularly important with 2S, 3S, 4S or 6S batteries.

I consider the balance connector an essential part of the system. It is not only used to display information on the charger.

How Many Amps Should You Use to Charge a LiPo?

Unless the manufacturer specifies otherwise, charging at 1C is a simple reference point.

The calculation is:

charging current = capacity in Ah × charging rate

For a 5,000 mAh battery:

5 Ah × 1C = 5 A

For a 2,200 mAh battery:

2.2 Ah × 1C = 2.2 A

Here are some examples:

Some batteries support faster charging. I would only use this option if explicitly authorised by the manufacturer.

Can You Charge a LiPo at 2C or Higher?

Yes, with certain batteries designed for this purpose, but only within the limits specified by the manufacturer.

Fast charging is not automatically acceptable simply because the charger can provide a high current.

The battery itself must support it.

If the specifications state a maximum of 1C, I stay at 1C.

What Precautions Should You Take When Charging?

A LiPo battery should remain under supervision while charging, on a suitable surface and away from flammable materials.

Before starting the charging process, I check:

• that the pack is not swollen;

• that it is not punctured or damaged;

• that the cables are in good condition;

• that the connector is correct;

• that the selected number of cells matches the battery;

• that the charging current is appropriate;

• that the balance connector is correctly connected.

Scientific MHD recommends charging between 15°C and 35°C and specifies that a battery should be allowed to cool before being recharged.

I therefore do not immediately recharge a LiPo battery that has just completed a particularly demanding run.

Can You Leave a LiPo Charging Unattended?

No.

Even with a modern charger, I stay nearby while the battery is charging.

I always charge a LiPo using a suitable LiPo charger, selecting the correct number of cells and charging mode.

A damaged battery may behave differently from a healthy pack.

A LiPo safety bag can provide additional protection, but it does not make unattended charging a safe procedure.

Scientific MHD offers LiPo protective bags and cases in its accessories range.

How Do You Use a LiPo Without Over-Discharging It?

I monitor the voltage and the model's behaviour and stop using it before reaching a deep discharge.

A LiPo battery that is discharged too deeply can permanently lose capacity and performance.

Scientific MHD specifies 3.3 V per cell as the recommended threshold, with 3.0 V per cell as the strict minimum.

I therefore strongly prefer landing or stopping the model when it begins to show the first signs of reduced power rather than waiting for a complete cut-off.

A LiPo alarm can warn you when the voltage drops too low and allow you to stop your model before excessive discharge occurs.

What Voltage Should You Avoid Reaching During Use?

The voltage to monitor is that of each individual cell, not just the total pack voltage.

For example, with a 3S battery:

• 3.3 V/cell corresponds to approximately 9.9 V;

• 3.0 V/cell corresponds to approximately 9.0 V.

For a 4S battery:

• 3.3 V/cell corresponds to approximately 13.2 V;

• 3.0 V/cell corresponds to approximately 12.0 V.

However, the behaviour of the battery under load must be taken into account. Voltage may temporarily drop when the motor draws a high current and then rise again when demand decreases.

I therefore do not rely on a single figure displayed during acceleration. The ESC settings, LiPo alarm and overall behaviour of the model should be considered together.

Why Does a LiPo Battery Get Hot?

A LiPo battery heats up when it has to deliver a high current, but excessive heating can indicate an incorrectly sized battery or power system.

There can be several causes:

• current demand is too high;

• insufficient C rating;

• ageing battery;

• high internal resistance;

• motor drawing too much current;

• excessive drivetrain resistance;

• poor ventilation;

• high ambient temperature;

• prolonged operation at high power.

Scientific MHD recommends allowing a battery whose surface temperature exceeds 65°C to cool before using it again.

If your battery regularly becomes very hot, I would investigate the cause rather than simply choosing a battery with more mAh.

How Can You Tell Whether a LiPo Battery Is Still in Good Condition?

I look at its physical condition, voltage, behaviour under load and changes in performance.

A LiPo battery can still accept a charge while performing significantly worse than when it was new.

What Does a Swollen LiPo Battery Mean?

A swollen LiPo battery must be taken out of service and must no longer be charged.

Swelling indicates deterioration of the battery pack and may be associated with a build-up of gas inside the cells. Scientific MHD states that a swollen battery is no longer usable.

I never puncture a swollen cell in an attempt to repair it.

What Are the Signs of a Worn LiPo Battery?

I monitor in particular:

• a noticeable reduction in runtime;

• loss of power;

• unusual heating;

• swelling;

• a cell becoming unbalanced;

• a significant increase in internal resistance;

• voltage collapsing under heavy load.

Internal resistance is particularly useful for monitoring how a battery pack changes over time.

An increase in internal resistance can result in greater voltage sag when the motor demands current.

What Voltage Difference Between Cells Should You Monitor?

Scientific MHD currently provides the following balancing guidelines:

These figures are guidelines taken from instructions published by Scientific MHD. For a battery showing unusual behaviour, I also refer to the manufacturer's recommendations.

How Do You Store a LiPo Battery?

For storage, I keep a LiPo at around 3.8 V per cell, in a dry, temperate location away from flammable materials.

Storage is often overlooked. However, a battery spends a large part of its life without powering a model.

At What Voltage Should You Store a LiPo?

A practical reference is approximately 3.8 V per cell.

The corresponding values are:

Specialist guides generally recommend a range of around 3.8 to 3.85 V per cell for storage.

AMA Flight School recommends 3.8 to 3.9 V per cell for storage periods longer than one week.

This is precisely why advanced chargers feature a Storage mode.

Why Shouldn't You Store a LiPo Fully Charged?

A cell at 4.2 V is at its maximum charging voltage. Leaving it in this state for a long period accelerates ageing.

I can leave a battery charged before an upcoming use, but if I know that the model will not fly or run for several weeks, I put the battery into Storage mode.

Specialist storage recommendations agree on this point: a LiPo that will remain unused should be brought to its storage voltage rather than kept fully charged.

Can You Store a Completely Empty LiPo?

I strongly avoid doing so.

A battery that is already at a very low voltage may continue to lose voltage during storage. Excessive discharge can then damage the cells.

After a session, if the battery is not going to be used again soon, I prefer to bring it back to Storage voltage rather than putting it away as it is.

Where Should You Store LiPo Batteries?

I look for a location that is:

• dry;

• temperate;

• away from heat sources;

• away from easily flammable materials;

• protected from impacts;

• out of reach of children.

A specific LiPo battery protection solution can be used to limit the consequences of an incident.

I do not leave my batteries in a car, especially when it can become very hot in direct sunlight.

Significant temperature fluctuations are not suitable for storage.

Current industry recommendations also advise against very hot locations, vehicles and damp areas.

To store LiPo batteries more safely, I can use a LiPo safety bag for additional protection during charging.

For several batteries, a fire-resistant LiPo case can be more practical.

Should You Check a LiPo During Long-Term Storage?

Yes.

For a battery that remains unused for several months, I periodically check its condition, voltage, connections and whether there is any swelling.

Scientific MHD currently recommends checking the battery every three months during prolonged periods of inactivity.

What Should You Do with a Swollen or Damaged LiPo?

A swollen, punctured or significantly damaged battery must no longer be charged or used.

I isolate it from other batteries, handle it carefully and take it to an appropriate battery collection facility.

I do not puncture it. I do not dispose of it with household waste.

Scientific MHD recommends taking used or damaged batteries to an approved recycling centre or contacting the retailer or local authority to find the appropriate disposal facility.

Which Mistakes Reduce the Lifespan of a LiPo Most Quickly?

Poor habits are often more damaging than simply choosing the wrong capacity.

Here are the main mistakes I try to avoid:

The main rule I remember is: a LiPo battery should be treated as a power system component that needs to be monitored, not simply as a battery that you charge and forget about.

What Routine Should You Follow Before and After Each Use?

A routine lasting just a few minutes can help detect problems very early.

Before Using the LiPo

I check:

1. the overall condition of the pack;

2. that there is no swelling;

3. the condition of the cables;

4. the connector;

5. the overall voltage;

6. cell balance;

7. that the battery is securely fitted in the model.

I also check that the battery still matches the model's configuration.

This is particularly important after changing the motor or ESC.

After Use

I disconnect the battery from the model.

I then check its temperature and external condition.

If it is very hot, I allow it to cool before charging.

Scientific MHD explicitly recommends allowing the battery to cool before recharging it.

If I know that I will use the battery again soon, I can leave it in a suitable state for the next use while following the manufacturer's recommendations.

If it will remain unused, I switch it to Storage.

This simple routine helps prevent finding a battery several weeks later that has been left fully charged or almost empty inside a model.

How Long Can a LiPo Battery Last?

There is no universal number of cycles that applies to all LiPo batteries.

Lifespan depends on discharge depth, temperature, current demand, battery pack quality, charging, storage and use.

I am therefore cautious about claims that systematically promise “100 cycles”, “200 cycles” or “500 cycles”.

Specialist sources provide very different ranges depending on the application and the criteria used to define the end of a battery's life.

A battery is not necessarily completely “dead” when it begins to lose performance.

It may still accept a charge but no longer be suitable for an application requiring high current.

Its actual behaviour should determine when it needs to be replaced.

How Do I Know Whether My LiPo Battery Is Still Suitable for My Model?

I ask myself five simple questions:

• Does the voltage still match the motor and ESC?

• Does the battery maintain its usual runtime?

• Does it heat up normally?

• Do the cells remain correctly balanced?

• Does the pack show any swelling or damage?

If the answer becomes negative on several points, I do not try to artificially extend its use.

A battery that still works at low power may, for example, no longer be suitable for a heavily loaded RC car or aircraft.

Voltage loss under load is then a useful indicator to monitor.

What Equipment Can Make LiPo Battery Management Easier?

A few accessories make battery monitoring much easier.

A charger** with LiPo balancing** allows you to manage charging and Storage mode correctly.

A LiPo tester allows you to quickly check the overall voltage and the voltage of the individual cells. Scientific MHD offers the Cellmeter 8, as well as various LiPo testers and alarms.

A fire-resistant LiPo bag or a suitable case adds protection during charging and storage.

I also find it useful to group batteries by model and note their age or frequency of use.

This makes it easier to identify a battery pack that is beginning to lose performance.

LiPo Battery FAQ

Which LiPo Battery Should I Choose for My RC Model?

First choose the number of cells required by the motor and ESC. Then check the capacity, current demand, C rating, dimensions, weight and connector.

What Is the Difference Between a 2S and 3S LiPo?

A 2S battery has a nominal voltage of 7.4 V, compared with 11.1 V for a 3S battery. A 3S therefore supplies a higher voltage to the motor and ESC and should only be used if the power system supports it.

What Is the Difference Between a 4S and 6S LiPo?

A 4S battery provides 14.8 V nominal, compared with 22.2 V for a 6S battery. The maximum voltage increases to 16.8 V and 25.2 V respectively when the cells are fully charged.

What Does 5000 mAh Mean on a LiPo?

5000 mAh corresponds to the nominal electrical capacity of the pack, or 5 Ah. A higher capacity can increase runtime, but it can also increase weight and size.

What Does 45C Mean on a LiPo Battery?

45C is the discharge rating specified by the manufacturer. For a 5 Ah battery, the theoretical calculation gives 5 × 45 = 225 A. However, this figure should not be considered a current that is actually guaranteed under all conditions.

How Do You Calculate the Theoretical Maximum Current of a LiPo?

Multiply the capacity in Ah by the C rating. A 3,000 mAh battery, or 3 Ah, rated at 30C therefore gives a theoretical current of 3 × 30 = 90 A.

How Many Amps Should You Use to Charge a LiPo?

Unless the manufacturer specifies otherwise, charging at 1C is a simple reference point. A 5,000 mAh LiPo is therefore charged at 5 A at 1C.

Should You Charge a LiPo in Balance Mode?

For multi-cell packs, Balance mode allows the charger to monitor and balance the individual cells. Scientific MHD recommends using a dedicated LiPo balance charger.

What Voltage Should a Fully Charged LiPo Have?

A LiPo cell is fully charged at 4.2 V. A 3S battery therefore reaches 12.6 V and a 4S battery 16.8 V when fully charged.

What Voltage Should You Avoid Reaching During Discharge?

Scientific MHD recommends not dropping below 3.3 V per cell and specifies 3.0 V per cell as the strict minimum.

Why Does My LiPo Get Hot?

A battery can become warm when supplying a high current. Excessive heating can, however, indicate an undersized, ageing or overworked battery, or a problem with the power system.

Why Does a LiPo Swell?

Swelling indicates battery deterioration and a build-up of gas inside the cell. A swollen battery must no longer be used or charged.

At What Voltage Should You Store a LiPo?

I recommend aiming for approximately 3.8 V per cell in Storage mode. Recommendations published by various RC modelling specialists generally fall within a range of around 3.8 to 3.85 V per cell.

Can You Store a LiPo Fully Charged?

For a short period before use, this may happen. For long-term storage, it is better to use Storage mode to avoid keeping the cells at their maximum voltage for several weeks.

Can You Store a LiPo Completely Empty?

I advise against it. A battery that is already at a very low voltage can continue to lose voltage during storage and become excessively discharged.

How Long Can You Store a LiPo Without Using It?

A LiPo can remain stored for a long period if it is kept under suitable conditions, at the correct storage voltage and checked periodically. Scientific MHD recommends checking it every three months during prolonged periods of inactivity.

How Can You Tell If a LiPo Battery Is Dead?

I check for swelling, cell balance, the battery's ability to maintain its voltage under load, its temperature and its runtime. A significant loss of performance or excessive internal resistance may indicate that it is time to replace it.

Can You Use the Same LiPo Battery on Several RC Models?

Yes, provided that the voltage, capacity, available current, dimensions, weight and connector are compatible with each model. A battery suitable for a glider is not automatically suitable for a very powerful brushless RC car.

Should You Let a LiPo Cool Down Before Recharging It?

Yes. A battery that has just been subjected to heavy use should be allowed to cool before recharging. Scientific MHD recommends allowing the battery to cool before charging it again.