LiPo battery balance connectors can easily get damaged by spinning propellers, especially on FPV drones where the balance lead is often dangling around. A damaged balance connector should be dealt with immediately. Exposed wires or damaged pins can short together, potentially causing the battery to overheat or even catch fire.
In this tutorial, I’ll explain how to replace a damaged balance connector, and how to prevent getting your balance lead damaged in the first place.
What Is the Balance Lead For?
The balance connector gives you access to the voltage of each individual cell in a LiPo battery. It is mainly used for checking individual cell voltages and balance charging.
For more information about LiPo batteries, check out my LiPo battery tutorial: https://oscarliang.com/lipo-battery-guide/#Balance-Connector
Below are examples of 4S and 2S LiPo batteries showing how the balance lead connects to each cell.
What Should You Do If the Balance Lead Is Damaged?
Before attempting a repair, inspect the battery carefully.
Also inspect the battery for physical damage such as:
- Swelling
- Punctures
- Torn outer wrapping
- Damaged cell tabs
- Burn marks
- Unusual heat or smell
Then, check the voltage of every cell and make sure they are within a safe range and reasonably balanced. A damaged balance connector may have shorted some of the wires together, potentially causing one or more cells to become over-discharged.
If the battery itself is damaged or any cell voltage is abnormally low, it may be safer to just retire the pack rather than repair it. Here is my guide on how to dispose of a LiPo battery safely: https://oscarliang.com/dispose-lipo-battery-safely/
If the pack is physically undamaged and all cell voltages look normal, and you believe it’s still safe to use, you may proceed with replacing the balance connector.
Get a Replacement Balance Connector
Whenever you retire old LiPo batteries, it is worth keeping their balance leads and connectors. They can be useful as replacements in the future. When should you retire LiPo? Check out our guide to find out: https://oscarliang.com/when-retire-lipo-battery/
If you don’t have any spare connectors, you can buy new balance connectors:
Make sure the replacement connector has the correct number of pins/wires for your battery. 2S requires 3 pins, 4S requires 5pins, 6S requires 7 pins, etc.
How to Replace a Damaged Balance Connector
When replacing balance connector, the most important rule is:
Never cut more than one wire at the same time.
If two exposed balance wires touch, they can short one or more cells directly.
Start with the lowest-potential wire, which is normally the black ground wire.
Cut that wire, strip a small section of insulation, then connect it to the corresponding wire on the new balance connector.
Insulate the solder joint immediately with heat-shrink tubing before moving on to the next wire.
Then continue working through the balance wires one at a time until all of them have been transferred to the new connector.
Working one wire at a time greatly reduces the risk of accidentally shorting the battery.
How to Identify the Balance Wires with a Multimeter
During repair, if you are unsure which wire corresponds to which cell, use a multimeter rather than guessing. I have a tutorial on how to use a multimeter: https://oscarliang.com/multimeter-fpv/
- Set the multimeter to DC voltage.
- Place the negative probe on the battery’s main negative terminal (the black wire on the XT60 discharge lead).
- Then touch the positive probe to each balance wire in turn.
- The voltage should increase as you move through the balance connector.
For example, on a charged 4S LiPo you might see approximately:
- Second wire: 3.7V
- Third wire: 7.4V
- Fourth wire: 11.1V
- Fifth wire: 14.8V
The exact voltages depend on the battery’s state of charge.
This makes it easy to confirm the correct wire order before soldering.
Check Your Work Before Charging
After replacing the connector, check the balance plug with a multimeter before connecting the battery to a charger.
Confirm that:
- The wire order is correct
- There are no shorts between adjacent pins
- Each cell voltage looks reasonable
- The total voltage measured through the balance connector matches the battery voltage
Only connect the battery to a charger once you are confident the wiring is correct.
How to Prevent Cutting Your Balance Lead
Simplest way is to use a rubber band to secure it. More detail here: https://oscarliang.com/secure-lipo-balance-lead/
LiPo Balance Connector Protectors
You can also use a LiPo balance connector protector, sometimes called a balance plug saver, to reduce the chance of damaging the connector.
You can find them here:
These protectors are not indestructible, and part of the balance lead may still remain exposed, but they offer considerably more protection than leaving the connector completely unprotected.
It is still a good idea to secure the balance lead so it cannot reach the propellers during flight.
Final Tips
Replacing a damaged LiPo balance connector is a relatively simple repair, but the battery is still live throughout the entire process.
The most important things to remember are to work carefully, only expose one wire at a time, insulate each connection before proceeding, and verify the finished connector with a multimeter before charging.
If the battery shows signs of physical damage or abnormal cell voltages, replacing the connector may not be worth the risk. In that case, safely retiring the battery is usually the better option.
Edit History
- Apr 2015 – Article created
- Sep 2018 – Updated
- Aug 2026 – Updated guide and product links
