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Writer's pictureJustin Davis

Parallel Lipo Charging 101

Parallel Charging 101


It seems like a mystery and possibly dangerous! - We will help you understand how it works.


LiPo parallel charging is a convenient and efficient technique for charging multiple LiPo batteries at once, utilizing a single charger. By connecting the batteries in parallel, users can avoid the tedious process of constantly unplugging and plugging in batteries during charging.


The Parallel Charging Connection and Process


In a parallel charging configuration, LiPo batteries are linked through a parallel charging board, effectively creating a larger battery with a combined capacity while retaining the initial voltage. For instance, when charging six 6S 1500mAh LiPos using a parallel charging board, the process is equivalent to charging a single 6S 9000mAh battery.


The individual cells within each battery are also connected in parallel, ensuring balanced cell voltages across all batteries. From the perspective of the charger, this setup is indistinguishable from charging a single battery.


1. Compatibility check:

  • Ensure batteries have the same cell count (e.g., 3S, 4S) and similar states of charge.

  • Verify that the parallel charging board is compatible with the batteries' connectors (e.g., XT60, XT30).


2. Connect batteries to the parallel charging board:

  • Plug the main discharge leads (XT60, XT30, etc.) of each battery into the corresponding connectors on the parallel charging board.

  • Plug the balance leads of each battery into the balance ports on the parallel charging board, ensuring they match the cell count (e.g., 3S balance lead into a 3S balance port).


3. Connect the parallel charging board to the charger:

  • Attach the main connector and balance connector (if applicable) from the parallel charging board to the charger.


4. Set the charger parameters:

  • Set the charger to the appropriate battery chemistry (LiPo).

  • Select the combined cell count of the connected batteries (e.g., 3S, 4S).

  • Calculate the combined capacity by adding the mAh capacities of all connected batteries (e.g., three 1000mAh batteries have a combined capacity of 3000mAh) and input the value into the charger.


5. Choose the charge rate:

  • Select a safe charge rate, typically 1C, based on the combined capacity (e.g., 3A for a 3000mAh combined capacity).


6. Initiate the charging process:

  • Start the charging process on the charger and monitor the progress closely.

7. Monitor the charging process!

  • Keep an eye on the charging process for any signs of overheating, swelling, or voltage imbalances.

  • Never leave the charging batteries unattended. See Justin's Heat tip below fora crucial safety tip.


Selecting the Right Parallel Charging Board


When it comes to parallel charging, a parallel charging board is an essential tool for safely connecting multiple LiPo batteries in parallel. These boards typically come with built-in protection features, such as fuses, to safeguard both the charger and the batteries from potential damage due to current surges.

To engage in parallel charging, simply connect both the XT30/XT60 connector and the balance connector from the LiPo battery to the parallel charging board. Most boards can accommodate 4 to 6 batteries, which is sufficient for the needs of most pilots.


Although there is a wide variety of inexpensive and basic options on the market, we advise opting for a board with safety features to reduce the risk of user errors. A simple, budget-friendly board with fuses, such as this one, serves as an excellent starting point. We like the Hglrc THOR Parallel Charging Board below as linked here.


Know the Difference between Parallel Charging, Series Charging, and Balance Charging

Parallel Charging

Parallel charging involves connecting multiple LiPo batteries to each other using a specialized board or harness. This configuration allows all negative leads to be linked together, while all positive leads are also connected. By doing so, the entire battery packs are placed in parallel. To balance the cells with a charger, the balance wires of all batteries must be connected, effectively putting the individual cells in parallel with each other. This method allows the charger to "see" all connected batteries as a single, larger battery, with a capacity equal to the sum of their individual capacities.


Balance Charging

Balance charging, on the other hand, is a method where each LiPo battery is charged individually, and the charger monitors and adjusts the voltage of each cell within the battery. This ensures that all cells within the battery pack have the same voltage, preventing any cell from becoming overcharged or undercharged. Typically, balance charging is performed using a balance charger, which has a separate port for connecting the battery's balance plug.


Series Charging

LiPo series charging is a method where LiPo batteries are connected end-to-end in such a way that the positive terminal of one battery is linked to the negative terminal of the next battery. This arrangement increases the overall voltage of the connected batteries while maintaining the same capacity. It is crucial to use batteries with the same capacity and state of charge when charging in series to ensure safe and balanced charging. However, series charging of LiPo batteries is not a common practice due to the higher risk of imbalanced cells and the need for specialized chargers.


Charging Different MAH sizes [ NOT mixing up 6s, 4s, 3s, etc. ]


Charging LiPo batteries with different mAh capacities in parallel is possible, but it is essential to follow the correct procedure to ensure safe and efficient charging. Here's how to do it:

  1. Ensure same cell count: Only charge batteries with the same cell count (e.g., 3S, 4S) in parallel. Mixing batteries with different cell counts can lead to dangerous situations, such as fires.

  2. Check the state of charge: Ideally, the batteries being charged in parallel should have a similar state of charge. Significant differences in the state of charge can cause high current flows between batteries, leading to potential damage.

  3. Use a parallel charging board: A parallel charging board is required to connect the batteries safely. Make sure the board supports the type of connectors (e.g., XT60, XT30) your batteries use.

  4. Connect the main leads: Plug the main discharge leads (XT60, XT30, etc.) of each battery into the corresponding connectors on the parallel charging board.

  5. Connect the balance leads: Plug the balance leads of each battery into the balance ports on the parallel charging board, ensuring they match the cell count (e.g., 3S balance lead into a 3S balance port).

  6. Set the charger: Connect the parallel charging board to your charger. Set the charger to the appropriate battery chemistry (LiPo), cell count, and combined capacity. To calculate the combined capacity, add the mAh capacities of all connected batteries (e.g., if charging a 1000mAh and 1500mAh battery, set the charger to 2500mAh).

  7. Charge rate: Choose a charge rate suitable for the combined capacity. It is generally safe to charge at 1C, which means charging at a rate equal to the combined capacity (e.g., 2.5A for the 2500mAh combined capacity in the previous example).

  8. Monitor the charging process: Keep an eye on the charging process and check for any abnormal battery behavior, such as excessive heat, swelling, or voltage imbalances.

Remember that charging LiPo batteries with different mAh capacities in parallel might result in uneven wear on the batteries, as the smaller capacity battery will experience a higher relative discharge rate during use. It is best to use batteries with similar capacities and states of charge for parallel charging to ensure the longevity and safety of your batteries.


Can I charge one Lipo with my Parallel Charging board?

To safely charge a single LiPo battery using a parallel charging board, follow these steps:

  1. Compatibility check: Ensure that your parallel charging board is compatible with your LiPo battery's connectors (e.g., XT60, XT30) and cell count (e.g., 3S, 4S).

  2. Connect the main lead: Plug the main discharge lead (XT60, XT30, etc.) of the LiPo battery into one of the corresponding connectors on the parallel charging board.

  3. Connect the balance lead: Plug the balance lead of the LiPo battery into the corresponding balance port on the parallel charging board, ensuring that it matches the battery's cell count (e.g., 3S balance lead into a 3S balance port).

  4. Set the charger: Connect the parallel charging board to your charger. Set the charger to the appropriate battery chemistry (LiPo), cell count, and capacity (mAh) of the battery you're charging.

  5. Charge rate: Choose a charge rate suitable for your battery's capacity. It is generally safe to charge at 1C, which means charging at a rate equal to the battery's capacity (e.g., 1A for a 1000mAh battery).

  6. Start charging: Initiate the charging process on your charger, and closely monitor the charging progress. Keep an eye out for any abnormal behavior, such as excessive heat, swelling, or voltage imbalances.

Even though you're using a parallel charging board, charging a single LiPo battery follows the same basic principles as charging it directly with a balance charger. The main difference is the use of the parallel board as an intermediary connection between the charger and the battery. Remember to always follow safety guidelines and never leave a charging battery unattended. Justin's HEAT TEST : Another tip is to touch each battery with your hand to check if they are getting hot. Generally a lipo will start to get hot before it starts to swell and burst into flames. Keep a close eye on your batteries while they are charging. I do this every time when charging. Especially with small batteries. I have had the most fires with small batteries. You have seconds to get it outside if you hear a fizzing sound, see swelling, smell smoke, or feel a hot battery. Get it outside!!!!


Charging multiple 1S Batteries at once


To charge multiple 1S LiPo batteries simultaneously using a parallel charging board, first ensure that the board is compatible with the batteries' connectors (e.g., PH2.0, JST). Connect each battery's main lead to the corresponding connector on the parallel charging board. Since 1S batteries do not have balance leads, there is no need to connect them. Next, connect the parallel charging board to your charger and set the charger to the appropriate battery chemistry (LiPo) and combined capacity of all connected batteries. Choose a safe charge rate, typically .5C, and initiate the charging process. Monitor the charging progress closely, watching for any signs of overheating, swelling, or other abnormal battery behavior, and never leave charging batteries unattended of course. - This is the 1S Parallel Charging board we like [ Link here ]


Careful not to mix up batteries with different cell counts. Why?

It is crucial to parallel charge only batteries with the same cell count to ensure safe and efficient charging. When batteries with different cell counts are connected in parallel, it can result in significant voltage differences between the cells. This disparity can lead to high current flows between the batteries, causing them to overheat and potentially resulting in damage or fires. By charging batteries with the same cell count in parallel, the voltages of individual cells are evenly distributed, allowing for a balanced and safe charging process. Mixing batteries with different cell counts not only jeopardizes the safety of the charging process but also reduces the lifespan and performance of the batteries. - MOSTLY IT IS DANGEROUS!


How to determine the charge current of a lipo battery on your charger


Setting the right charging current for a LiPo battery requires taking the battery's capacity into account and adhering to the 1C charging rule. The 1C rule implies charging the battery at a current equal to its capacity. The breakdown equation for determining the charging current is as follows:

Charging Current (A) = Battery Capacity (mAh) / 1000

For example, consider three different LiPo batteries with capacities of 500mAh, 1000mAh, and 2000mAh.

  1. For a 500mAh LiPo battery, you would charge it at a 0.5A current (1C): Charging Current (A) = 500mAh / 1000 = 0.5A

  2. For a 1000mAh LiPo battery, you would charge it at a 1A current (1C): Charging Current (A) = 1000mAh / 1000 = 1A

  3. For a 2000mAh LiPo battery, you would charge it at a 2A current (1C): Charging Current (A) = 2000mAh / 1000 = 2A

Begin by connecting the battery to the charger using appropriate connectors and balance leads, if applicable. Set the charger to the correct battery chemistry (LiPo) and select the battery's cell count (e.g., 3S, 4S). Then, use the breakdown equation to set the charging current based on the 1C rule. Bear in mind that some batteries may support higher charging rates, as specified by the manufacturer. Always consult the battery's documentation to determine the maximum safe charging rate and closely monitor the charging process for any signs of overheating, swelling, or other abnormal battery behavior. Justin Best Charging Tip : I frequently charge using the "Slow Charge" method. Example : Cutting the suggested "C" charge rate by half or 50% less. Yes it takes longer, but it is safer, swell less, and your lipo could last 10 years. Justin still has batteries from 2013 or older that can still fly. Fast charging

stresses the battery and lessens the life span.


Why Parallel Charge?


FPV pilots parallel charge LiPo batteries due to the numerous advantages it offers. Parallel charging allows multiple batteries to be charged simultaneously, saving time and energy compared to charging each battery individually. This efficiency is particularly valuable for FPV pilots who often require multiple charged batteries for extended flight sessions or competitive events.


Furthermore, parallel charging enables balanced cell voltages across all connected batteries, ensuring optimal performance and prolonging battery lifespan. By adhering to safety guidelines and using appropriate equipment such as parallel charging boards, FPV pilots can enjoy the convenience and effectiveness of parallel charging, maximizing their flight time and overall flying experience.

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