How to Balance Charge a LiPo Battery

To balance charge a LiPo battery, connect both the main power lead and the balance plug to a compatible charger, select the correct battery chemistry and series cell count, set an appropriate charging current, and choose LiPo Balance Charge. Before pressing Start, confirm that the charger’s detected S count matches the battery label.

Quick answer: Balance Charge should normally be the default full-charge program for conventional multi-cell RC LiPo batteries. The main lead carries most of the charging current, while the balance lead allows the charger to monitor and correct individual cell voltages. A standard LiPo normally finishes close to 4.20V per cell.

Do not begin charging if the pack is swollen, punctured, leaking, unusually hot, producing an abnormal smell, or showing damaged main or balance wires. Balance charging can correct limited voltage differences, but it cannot repair a physically damaged or failing cell.

Balance Charge Settings at a Glance

What Does Balance Charging Mean?

A multi-cell LiPo battery contains two or more cells connected in series. The charger must control the total pack voltage while also preventing any individual cell from exceeding its intended voltage limit.

Balance charging uses two electrical connections:

• Main power lead: Carries most of the charging current.
• Balance lead: Gives the charger access to each series cell group.

For example, a standard 4S LiPo has four series cell groups. When fully charged, the complete pack should be close to 16.8V, but the charger also needs to see that the individual cells are close to 4.20V rather than only relying on the total.

A total voltage of 16.8V could still hide an unsuitable distribution such as one cell being too high and another too low. That is why total pack voltage alone is not enough.

Why LiPo Cells Become Unbalanced

Cells in the same battery are similar, but they are not perfectly identical. Small differences develop from:

• Manufacturing variation
• Internal resistance differences
• Uneven temperature
• High-current use
• Battery age
• Repeated deep discharge
• Physical damage
• Storage condition
• Balance-wire or connector resistance

One cell may therefore reach the upper voltage limit before the others. A balance charger reduces current and uses its balancing circuit to control the leading cell while the lower cells continue to rise.

Limited imbalance can be normal. A cell that repeatedly drifts farther from the others may indicate battery aging, a weak cell or a balance-connection problem.

Before Balance Charging: Inspect the Battery

Do not use the charger as the first test of a visibly questionable pack. Inspect the battery before connecting it.

Do not balance charge a battery that is:

• Swollen or changing shape
• Punctured or crushed
• Leaking
• Smoking or hissing
• Producing an unusual chemical smell
• Unusually hot before charging
• Showing melted connector plastic
• Showing exposed wires or reversed polarity
• Missing or damaging balance-lead contacts

Also inspect the charger output lead, adapters and balance-board ports. A damaged balance connector can cause incorrect cell readings or repeated connection errors.

For the wider safety procedure, read How to Charge a LiPo Battery Safely.

Step 1: Identify the Battery Chemistry

Read the battery label carefully. A standard LiPo, LiHV, LiFe and Li-ion battery may use different charger programs and voltage limits.

This article focuses on conventional RC LiPo batteries. Select LiPo, not LiHV, even when the higher-voltage setting appears to offer more runtime.

Step 2: Confirm the Cell Count

The S rating tells you the number of cells connected in series. It determines the complete pack voltage.

Check the label first. A conventional balance connector normally has one more wire than the series cell count:

• 2S commonly has 3 balance wires
• 3S commonly has 4 balance wires
• 4S commonly has 5 balance wires
• 6S commonly has 7 balance wires

This wire count is a useful cross-check, not a substitute for the battery label. Proprietary smart systems may use a different arrangement.

Step 3: Calculate the Charge Current

Approximately 1C is a conservative general starting point when the battery does not specify another recommended limit.

A battery may permit 2C, 3C or another charge rate, but the charger, input power supply, connector and charge lead must all support the increased current and wattage.

For the full calculation, read LiPo Charging Rates Explained.

Step 4: Connect the Main Power Lead

Follow the charger manufacturer’s connection procedure. Connect the correct charging lead to the charger output, then connect the battery’s main power connector.

The main lead may use:

• XT30
• XT60
• XT90
• EC3
• EC5
• IC3
• IC5
• Deans / T-Plug
• TRX
• QS8

Many programmable chargers use an XT60-style output, so a correctly wired charge lead or adapter may be required.

Before connecting:

• Confirm polarity
• Check the connector housing
• Inspect solder joints and wire insulation
• Make sure the charge lead is rated for the selected current
• Avoid long chains of adapters

For connector identification and adapter compatibility, visit the RC Battery Connector Guide.

Step 5: Connect the Balance Plug

Insert the battery’s balance connector into the charger’s correct balance port or balance board. The port must match the battery’s cell count and connector orientation.

Common conventional RC LiPo packs use JST-XH balance connectors, but layouts vary. Do not:

• Force the connector
• Insert it offset by one pin
• Reverse the orientation
• Pull the plug by its wires
• Use a visibly damaged balance extension

If the charger cannot read all cells, stop and inspect the plug, wires, balance board and charger port.

Step 6: Select LiPo Balance Charge

Open the charger task menu and select:

• Battery type: LiPo
• Mode: Balance Charge
• Cell count: matches the battery
• Current: matches the capacity and charge specification

Do not confuse Balance Charge with:

• Fast Charge: May shorten the final charging stage.
• Storage: Moves the battery toward a moderate resting voltage.
• Discharge: Removes energy toward a selected cutoff.
• Charge: May not provide the same balancing behavior depending on the charger.

For a complete comparison, read LiPo Charger Modes Explained.

Step 7: Verify Manual and Detected Cell Count

Many chargers compare the manually selected S count with the voltage detected from the battery. The two values must agree.

If the charger reports a cell-count mismatch, do not repeatedly confirm through the warning. Investigate:

• Wrong manual S setting
• Very low cell voltage
• Damaged balance wire
• Loose balance connector
• Incorrect balance-board position
• Battery damage

Step 8: Start the Balance Charge

Once all settings are verified, begin the charging task and remain present.

The charger will normally:

1. Confirm the battery connection.
2. Read total pack voltage.
3. Read individual cell voltages.
4. Apply the selected current during the constant-current stage.
5. Reduce current as the cells approach the upper voltage limit.
6. Correct cell differences during the balancing stage.
7. Terminate when the programmed conditions are met.

Do not cover the charger’s cooling vents. Keep the battery and charger on a stable, non-flammable surface away from combustible material.

What to Monitor During Balance Charging

Watch more than the remaining time estimate. Monitor:

• Total pack voltage
• Individual cell voltages
• Actual charging current
• Added capacity
• Battery temperature
• Connector and wire temperature
• Charger temperature
• Repeated warnings

Stop charging immediately if:

• The battery swells
• The pack becomes unusually hot
• A connector or adapter becomes hot
• You smell an abnormal chemical odor
• Smoke, leakage or melting appears
• One cell behaves very differently
• The charger loses the balance connection
• The displayed S count changes unexpectedly

A warm charger can be normal under load, but the battery and connectors should not show abnormal heating during a routine balance charge.

What Individual Cell Voltages Should Look Like

As charging progresses, the cell voltages should rise together. They do not need to display exactly the same number every second, but the difference should generally narrow near completion.

These examples are general illustrations rather than universal pass-or-fail thresholds. Charger resolution, battery temperature and measurement conditions can affect the displayed values.

Why the Final Part Takes Longer

Balance charging normally slows down near full voltage because the charger changes from the constant-current stage to the constant-voltage and balancing stages.

If one cell reaches the upper limit first, the charger must reduce the main current while the lower cells catch up. The process can become slow when:

• The pack begins significantly imbalanced
• The charger has low balance current
• One cell has higher internal resistance
• The battery is aging
• The balance connector has resistance
• A balance wire is damaged or intermittent

Increasing the main charging current does not necessarily make balancing faster. The limiting factor may be the charger’s balance circuit rather than bulk charging power.

For troubleshooting, read Why Is My LiPo Battery Taking So Long to Balance Charge?

How Long Does Balance Charging Take?

At approximately 1C, the theoretical capacity-replacement time is about one hour, but a complete balance charge often takes longer.

Actual time depends on:

• Starting state of charge
• Battery capacity
• Selected current
• Cell count
• Charger output watts
• Input power
• Cell balance
• Balance current
• Battery age and temperature

A partially charged, closely balanced battery may finish sooner. A pack with noticeable cell drift may spend a long time near the end even when the main charging stage was fast.

Balance Charge Examples for Common LiPo Batteries

The charger must also have enough wattage. A 6S 5000mAh battery at 1C requires approximately 126W near full voltage, while a 4S 5000mAh battery requires about 84W.

Can You Balance Charge at 2C?

Yes, when all of the following are true:

• The battery explicitly permits at least 2C charging
• The charger can provide the required current
• The charger has enough output wattage
• The AC or DC source can provide the required input power
• The charge lead and connectors are correctly rated
• The battery remains within an appropriate temperature range

Balance Charge does not mean the charger is limited to 1C. The charging mode and C rate are separate settings.

For example, a 5000mAh battery at 2C requires 10A. A 6S 5000mAh pack at that current requires approximately 252W near full voltage.

Balance Charge vs Fast Charge

Balance Charge is normally the preferred everyday program because it gives the charger time to monitor and correct individual cell differences.

Fast Charge may reduce time by:

• Ending the constant-voltage stage sooner
• Using a higher termination-current threshold
• Spending less time on final balancing
• Finishing with slightly less added capacity

Fast Charge is not automatically unsafe, but it should not be used to hide a battery that consistently takes a long time to balance.

Read Balance Charging vs Fast Charging for the dedicated comparison.

Can You Balance Charge Batteries in Parallel?

Yes, when the batteries are correctly matched and connected through a suitable parallel charging board. Parallel Charging is a connection method, while Balance Charge remains the charger program.

Before parallel balance charging, confirm:

• Same battery chemistry
• Same series cell count
• Closely matched starting pack voltage
• Closely matched individual cell voltage
• Suitable battery condition
• Correct combined-capacity current calculation
• Correctly rated parallel hardware

Read How to Parallel Charge LiPo Batteries Safely before building a parallel group.

What to Do When Balance Charging Finishes

When the charger reports completion:

1. Review the individual cell voltages.
2. Check the total pack voltage.
3. Confirm that no cell is above the intended voltage limit.
4. Inspect the battery for heat or swelling.
5. Stop the charger task before disconnecting where required.
6. Remove the balance connector by its housing.
7. Disconnect the main charge lead.
8. Keep the battery away from conductive objects.

Follow the charger manufacturer’s documented disconnection order where specified.

Do not leave the fully charged battery connected to the charger or balance board after the task has finished.

What If You Are Not Using the Battery Soon?

A fully charged LiPo should not remain at maximum voltage for extended periods. If plans change and the battery will not be used soon, use the charger’s Storage mode to move the pack toward a more suitable resting voltage.

Many chargers target approximately 3.8–3.85V per cell for a standard LiPo, although the exact programmed target may vary.

Storage mode may charge or discharge the battery depending on its starting voltage. Discharging can be slow because many chargers have much less internal discharge power than charging power.

Common Balance Charging Mistakes

• Selecting LiHV for a standard LiPo: This raises the intended final voltage beyond the standard LiPo limit.
• Choosing the wrong S count: The charger may target an unsuitable pack voltage.
• Connecting only the main lead: A conventional multi-cell pack normally needs the balance connection for Balance Charge.
• Offsetting the balance plug by one pin: This can damage the battery, board or charger.
• Ignoring cell-count warnings: Stop and investigate instead of repeatedly confirming through the error.
• Using the discharge C rating as the charge rate: Charge C and discharge C are different specifications.
• Assuming every 5000mAh pack needs the same charger power: Cell count changes the wattage requirement.
• Increasing current to fix slow balancing: The limiting factor may be balance current or battery condition.
• Charging a swollen or damaged battery: Balance Charge cannot repair physical damage.
• Leaving charging unattended: Automatic control does not remove the need for supervision.
• Using damaged adapters: Loose or undersized connections can heat up.
• Judging battery health from total voltage only: Individual cell behavior matters.
• Assuming Balance Charge repairs an old pack: It cannot reverse internal resistance growth or a weak cell.
• Leaving the battery full for storage: Use Storage mode when the pack will not be used soon.

Choosing a LiPo Balance Charger

A useful balance charger should provide:

• Support for the complete S-count range you use
• Correct LiPo and LiHV chemistry modes
• Clear individual cell-voltage display
• Adjustable charging current
• Enough output wattage for the largest battery
• Suitable balance current
• Balance Charge and Storage programs
• Reliable cell-count detection
• Appropriate AC or DC input
• Compatible main output and balance ports

Users charging multiple batteries may benefit from independent dual- or quad-channel chargers. Independent channels allow different batteries to use separate S counts, currents and modes without being electrically combined.

Browse the CNHL LiPo battery charger collection for balance chargers, dual-channel chargers and multi-channel systems.

For ToolkitRC chargers and charging equipment, visit the ToolkitRC collection.

Balance Charging FAQ

Should I balance charge my LiPo every time?

Balance Charge should normally be the default for conventional multi-cell LiPo batteries because it allows the charger to monitor individual cells throughout the charging process.

Do I need both the main lead and balance lead?

For most conventional multi-cell LiPo batteries, yes. The main lead carries the charging current, while the balance lead provides individual cell-voltage access.

Can I balance charge without the main plug?

Most conventional chargers require both connections because the balance lead is not intended to carry the complete charging current. Some specialized low-power systems operate differently, so follow the charger instructions.

Can I balance charge without the balance plug?

A conventional multi-cell LiPo cannot be properly balance charged without individual cell access. Do not bypass a damaged balance lead simply to complete the charge.

Does a 1S LiPo need balance charging?

No. A 1S battery has only one cell, so there are no cells to balance against one another. It still needs the correct charging mode, current and final voltage.

What voltage should each LiPo cell reach?

A standard LiPo normally finishes close to 4.20V per cell. A 4S pack therefore finishes near 16.8V total.

How close should LiPo cells be after balance charging?

Healthy cells should normally finish reasonably close to one another. Small differences can occur because of charger resolution and battery temperature. A persistent or increasing outlier should be investigated.

Why does my charger reduce current near full voltage?

The charger enters the constant-voltage and balancing stages. It lowers current to prevent cells from exceeding the intended voltage limit while lower cells catch up.

Why is my balance charge taking hours?

The pack may be significantly imbalanced, the charger may have low balance current, or a cell or balance connection may be abnormal. Check the individual readings rather than simply increasing current.

Can Balance Charge fix an imbalanced battery?

It can correct limited voltage differences during charging. It cannot repair a weak cell, physical damage or permanently increased internal resistance.

Can I balance charge at 2C?

Yes, when the battery explicitly permits 2C and the charger, power source, leads and connectors support the required current and wattage.

Can I balance charge two different batteries at once?

A dual-channel charger may charge two different batteries independently. Batteries combined on one parallel board must meet the stricter parallel-charging compatibility requirements.

Is Balance Charge safer than Fast Charge?

Balance Charge provides more complete individual-cell monitoring and is normally the preferred everyday program. Safe charging still depends on battery condition, settings, connections and supervision.

Final Balance Charging Checklist

Balance charging is the normal way to prepare a conventional multi-cell LiPo battery for use because it controls both total pack voltage and individual cell behavior. The process becomes straightforward once the same verification sequence is followed every time: chemistry, S count, current, main connection, balance connection, detected cells and final voltage.

For the wider charging system—including charger selection, charging rates, Fast Charge, Storage and parallel charging—visit the CNHL LiPo Battery Charging Guide.