How to do parallel charging ?

Hello again.

I bet you searched this post because you are tired of waiting x minutes multiplied with the number of batteries you have…fair enough...

Same was in my case. So, let’s talk about parallel li-po charging.

First you must understand that a li-po is basically a 3.7 V nominal voltage cell, so if you have a 3 cell li-po it is 3.7Vx3cells.

The fully charged voltage, is of 4.2 V per cell, so a total of 12.6 V. The lithium –polymer(li-po) batteries can be hooked in serial or parallel configuration (for example S or P, like 3SP1 which is same as 3S)but this is something already inside the battery, so it’s just a coding for understanding it.

Normally since the li-po batteries don’t like to be left depleted it is strongly suggested not to drain more than 3.8 Volts from each cell, otherwise in time they will not last long.

Now, to the real thing: you must understand that you are responsible if something goes wrong, and I am not to be held liable for anything related to your parallel charging…

From my experience I can tell you that if you use different charged level batteries, you can have problems, personally my balanced connector melted on a small 1050 mAh battery !

so be carefull to put only same battery type and same charge state battery(not fully depleted and fully charged together).

First of all you need a good balancing charger and a good power supply, and additionally you need a balancing charger board, personally mine can charge up to 6 packs.

Since you will charge in parallel, you must keep in mind that by doing this the voltage stays the same, but the Amp power(capacity) is added for each battery you want to charge.

For example: I want to charge 3 x 2200 mAh batteries….first I check the voltage to be similar, but since I fly my 450 heli and land when the timer shows 5 minutes, they should be very similar in voltage….Then I usually connect the power plug and balance plug for each battery, and when all are connected, I plug the balancing board power socket to my charger, and lastly I plug the balancing connector to the charger. With all this in place I check again the wires and charging board for abnormally hot areas and only if all is ok, I connect the power supply to the charger. Next, I select Li-po from the menu, 11.1V and this is important, you must select the charging current as the sum of all the cells you charge, in my case 2200+2200+2200=6.6A for 1C rate. If you have really strong supply and charger, you can charge your batts at 2C capacity, meaning 13.2A, but I don’t recommend this unless your parallel charging board is really top quality, otherwise you might burn it.

So, another quick example: I want to charge my Master CP batts, which are 3s at 1050 mAh. After carefully connecting them on my parallel charging board, I select Li-po, with 11.1 V and charging current will be 1050+1050+1050 which is 3150 for a 1 C charge rate. Usually I choose 3.2A. simple, right?

Just in case you didn’t know, each Li-Po battery has a supplier recommended charge rate, and for 1C it is the battery’s capacity, for 3 C is 3 times capacity(2200 with 3C, allows me to safely charge it at 3x2200=6.6A). If you have no specification on yours just play safe and charge it at 1C, meaning charging current should equal you battery capacity.

Also the batteries have a discharge rate C value, usually between 10c to 60 C with 5 units increase. The highest the C value the more current it can give and the faster it can be depleted.

For example if you have a 10C battery and you need 20C in your heli setup, the battery will get extremely hot and possibly after doing this one time, you can throw it out the bin.

Usually for a 450 size heli it’s recommended to have a minimum 20 C battery, and if you plan really hard 3D with it, you should consider a 30 or 35 C pack.

Keep in mind again:

You are the only responsible person if something bad happens;

Only parallel charge batteries of same type(only 3s, only 4s, etc) and charge state

After connecting your batteries to the parallel charging board, check if wires, bord or batteries get hot, if not, proceed to connecting the charger;

Select same voltage as a single battery, but charging current equal to the sum of your charged batteries capacities (for example 2 each 2200mAh- select 4400mAh)

ALWAYS supervise the charging, never leave parallel charging unattended

Be safe, since li-po are quite sensitive batteries.

Below is the movie I made for a better understanding of the process.

Pffff, sorry for the long explanations, but I hope it was worth reading, and now you can say you know more about the “juice” we use in our beloved hobby.

Thanks for reading, and happy flying