In nature, whenever a gradient exists, a natural balancing process will occur. A gradient means that there is a high concentration of something as compared to a low concentration of that same thing near it.
For example, if you pour salt into still water, the area of water where the salt is will become very salty. The same occurs with heat. Heat will naturally diffuse from a hot area into a cold area, attempting to find a balance. Pressure also follows this natural balancing process. Take a blown up balloon, for example, and untie it. There is a large pressure difference or gradient between the air in the balloon, and the air in the room.
The high-pressure air in the balloon will rush out into the lower-pressure air in the room, diffusing the high pressure into the lower pressure until an equilibrium pressure is achieved. Electricity also follows this principle of diffusion. The battery with the higher voltage will naturally push its charge electrons into the batteries with lower voltage, when plugged in parallel, until all batteries equalize to the same voltage. Since the individual cells of each battery are also in parallel with the individual cells of all the rest of the batteries, when the balance leads are connected in parallel by plugging them all into a parallel charge board , all of the strings of cells in parallel will also equalize to the same voltage.
Now, when you plug the entire parallel charge board balance lead into your charger, your charger will balance out the cells of each battery as if it was simply one large battery. The charger will "see" the first string of cells in parallel as a single "Cell 1," and the second string of cells in parallel as a single "Cell 2," and the third string of cells in parallel as a single "Cell 3," etc. The result is that in parallel charging, all cells come out properly balanced so long as the cells are not damaged, your charger is functioning properly, you plugged them all in properly, and nothing else is wrong!
Ex: 2S with 2S, 3S with 3S, etc. All batteries must be at similar discharge state. Ex: it is not as advisable to put a new battery with a 2 year old battery, but not critical as long as the batteries are similar capacities mAh ratings , the same cell count, and at similar discharge states.
This prevents high currents from flowing through the balance plugs as the batteries equalize based on their varying voltages upon plugging them in. The main plugs can take more current. The farther apart the batteries' charge states, the longer you should wait. Ex: parallel charging three 3S mAh 1. Therefore, in this scenario, a charge rate of 5. I like to place the entire charge board with all of the attached batteries, if possible, inside of the same charge bag.
If the batteries are very large, and this is not possible, feel free to separate the batteries into separate charge bags. Note: charge bags have a special slit in the side, near the velcro, to allow the cables to come out of the bag, so placing the entire charge board, or individual attached batteries, into a charge bag is not a problem. Feel free to Google for more info on "parallel charging" of LiPo packs.
Also see these links as additional sources:. Parallel charging all these batteries at once with only 3 chargers! Useful Plots:. The chart below is just a rough estimate of how much time is recommended to let the batteries equalize their voltages prior to plugging in their balance leads and starting the charger. A newer version of this article, with additional information and rules of thumb for parallel charging ie: that I keep more up-to-date , is available at its original posting location here.
I recommend you check it out. Other articles and general RC information are also available on my website, including many I've written on Arduino microcontroller programming. Visit me here: www. For additional general LiPo information:. You need to log-in to rate articles. Looking for your store account? Recommend This Article You need to log-in to rate articles. Related Articles.
And yeah Arx on January 30, This is also to monitor battery health. Why have we not made a device to balance cells in flight?
I balance charge all the time but it seems a few transistors should be plugged into the balance lead to keep each cell within. We all have that one cell that could use the help of its neighbor I think. If theres such a fuss over the risks during charging that ultimately all come from a cell being overcharged due to the other cells not being at the same voltage caused by resistance difference then why isnt the battery fitted with the balance circuit?
And who the hell came up with the stupidity to attach the charge wires balance leads to the battery and the fixed connector on the charger!? OMG someone tell these people they are doing it the wrong way around!! A balance circuit is built in to most chargers. Some Lipo batteries have balance circuits, but this adds cost and weight and is another component that can fail or become damaged Some people choose not to balance charge or buy chargers without a balance port.
Both lipos with balance circuits and chargers with balance ports are very rare because there is very little demand for them. Straight lipos and balance chargers are safely used by the vast majority of people. Most cameras or phones with removable batteries have different interfaces. Lipo batteries vary tremendously in cell count, capacity, size, shape, discharge rate and use.
All lead to different solutions, but one constant is the balance connector which almost all Lipos use. When it comes to connectors the differences are easily and routinely overcome with adaptors or by soldering new connectors. Having balance wires on the battery keeps the size of the pack down. A fixed female balance connector would add at least 5mm to the size of a battery pack.
This is quite a lot, particularly on smaller packs. The balance leads we have now are sometimes used as an alternative power feed are also quite easy to fix. Still, there are Lipos with female balance connectors, but they tend to be hard case packs for use in RC cars. There are weight, size and cost implications and soft case packs are still popular despite lots of hard case options being available. As above, there are hard case packs available, predominantly for RC cars.
Lipos are largely about getting as much energy and current from as small and light a package as possible. Much of what you ask for is already available. Depending on the size and voltage you use, you may find some suitable hard case options. Just search in broad terms including the words hard case and you might find something to suit. Also think outside the box. If you have a requirement for 4S packs you could use 2 x 2S saddle packs in series.
At the end of the day though, market forces shape the supply chain and you will find that the best options are the ones that are most widely available. Lipo safety is more about education than it is about the technology. Hi, I have a question regarding discharge of parallel connected LiPo batteries. I am connecting 2 6S LiPo batteries on my quadcopter. Since the batteries are connected in parallel will they try to charge each other? In such case there is no issues with slow charging a lipo I see none.
But curious what your take is. I have found using lower charge rates extends battery life. Just beginning with the lipo. I regularly parrallel charge, have for years and for the most part the packs come up fine. I disconnected the faulty pack, re-balanced the other packs to storage levels and then charged them to full. After this I put each one on a discharge cycle individually and on each one the cell which had the low voltage dropped voltage to 4.
My fault if I have, I should be checking all batteries before charging.. One question to all experts: fact ist: if you plug a SINGLE lipo to your charger and for example one of the balancer leads is damaged or you just forget to plug the balancer lead in your charger. Your charger would scream that something is wrong with the balancer plug. What would your charger see that? What will happen if you charge a lipo several times with a damaged balancer plug? Dont get me wrong I also parallel charge all the time but this is an importan safety point where unfortunately nobody mention anywhere.
Have you seen this banggood. Also there are more advanced parallel boards with fuses for each plug, so if you miss to check the voltage, they will cut off the power and possibly save your battery with the board. The instructions usually have a big red warning not to leave the batteries unattended. So how do keep them? Are they any good? Because when you first connect the batteries together, the difference in voltage will cause a large current flow before they are equalized.
Does the act of plugging them all in to the balance board do the equalisation or is there more to it? The board will connect the battery as one single battery without the charger turning on.
I wish to charge each battery at a maximum rate of 1C or less, which is 1. Each cell will have a final voltage of 4. Let us check to make sure that the power consumption will not exceed 50 W. At least we can charge all 3 batteries at 1C.
Odds are, the charger would blow up if I set it to charge at 5. The batteries will charge at a slower rate, but the charger will not be at risk. Thanks for the note, I will add some extra lines to point out the safety about charger power rating. I am using a computerized charger and it automatically sets upper bound limit on charger current. I might be getting too comfortable with this and forgot to mention the importance of correct charge current.
I charge my mAh 3S at 1C. Could it be because the amperage A the charger pumps in gets lower as the batteries build up voltage? First check the voltage of each pack and equalize to about 0. More important use only similar packs to parallel charge! My parallel charging boards come with poly-silicon fuses which almost instantly go to high resistance when they get hot with too much current.
Let them cool down and ready to go again. No need to replace burned out fuses. See the diagram below to get a better idea of the layout. As you can see, each cell inside battery 1 is connected to an identical cell inside battery 2. When the 2 identical cells are charged in parallel, they will equal each other out and charge as one massive cell.
Usually, to charge a lipo battery you just take whatever the capacity number is which in my case is 1. Then you tell the charger how many cells the battery has.
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