Everything you need to know about LiPo Battery chargers

charger
lipo
buying_guide

#1

In this guide we will discuss all the important things you need to know about using your LiPo battery charger. Investing in a a decent charger is a good idea as its something you will use often.

You cant just use any battery charger with your lithium polymer batteries as you need to use a LiPo compatible charger. This is due to the fact that these batteries have several cells that have a very specific voltage range. To learn more about this check out our other guide to learn the basics of lipo batteries. If you use a regular charger with a lipo battery you will end up causing your lipo to explode into a ball of flames :fire:, so dont do that (unless making a cool video on youtube in a controlled environment!)


Best LiPo Charger

To find out about the best lipo chargers we suggest, head over to our blog article:

Our original suggestions are below, but is now mainly outdated:

[details=Summary]For the best overall we currently suggest the imax B6 mini charger Here are a few suggestions that you can consider depending on your needs. At unmanned tech we have tested several chargers from various manufacturers and feel that this one is the best when you consider performance, usability and price.

Ultimate LiPo charger


The iMax B6 mini is our favorite charger and is the only charger you will ever really need as it is able to support all the main LiPo batteries from 2S to 6S. The other great thing about the B6 mini is its compact size so it does not take up much room at all in your toolbox. Using a more advanced charger like this ones gives you extra features that include the ability to discharge your lipo to storage mode and it also has the ability to charge other types of batteries too. However the two features that make this unit stand out from the rest is the options to add a wifi module so you set and monitor your charge from your smartphone via wifi. A temperature sensor can be attached to your battery for added safety so that your charger will stop charging if your battery gets too hot.

Everyday basic LiPo charger

If you are looking for something cheap and basic to get the job done the SkyRC E3 is our recommendation. It is priced to be very affordable but unlike some of the cheaper alternatives you dont have to worry about it incorrectly charging your lipos. I personally enjoy using these chargers as you dont need to set anything up, just plug in your balance lead and it will start charging. No need to specify the cell count, charge rate or set any other functions. The E3 charger can charge 2S, or 3S lipo batteries but if you want the ability to also charge up to 4S batteries you can also consider the SkyRC E4 charger. You will hardly ever come across higher cell count lipos unless fling more professional level drones so the E4 will undoubtedly be perfect for hobby level flying.[/details]


Battery charging rules

Its important to take note of these rules when charging your lipo battery

  1. Never charge your battery unattended - from time to time check to see if your battery is getting warm to the touch or starts to sewll, if so stop charging immediately and contact an expert immediately (like someone on dronetrest) before using the battery again.
  2. Never charge a damaged battery - dont charge if it is swollen (puffy) or has any other visible signs of damage
  3. Always charge your battery at 1C or less - many chargers allow you to set a charging rate, although most batteries can support up to 5C charge rates (which makes charging your battery much faster). Its always best to charge at 1C or less as this means the chemicals inside your battery will gain energy slower which keeps them more stable and ultimately means your battery will have a much longer life in terms of charge/discharge cycles.
  4. Try to charge your batteries in a fireproof location, or in a lipo safe bag. - this just adds an extra layer of protection
  5. Ensure the number of cells and battery type are set correctly on your charger to match the cell count in your battery. - this is only applicable for more advanced chargers.


Some things to consider when buying a charger

There are a few important specifications you should look at before buying a lipo battery charger.

Balance Charging
99% of Lipo chargers have the ability to perform balance charging. This process will check the voltages of each individual cell in your battery and ensure they all have the same voltage. This is a critical factory to monitor as if one of the cells voltage increases or drops below the required voltage range the battery could get damaged, or worse, catch fire!. Fortunately, as I mentioned basically all chargers have this ability.

an example of a battery connected to a balance charger

If you need to plug in the balance leads from your battery to you chargers, its a good indication that your charger has the balance function. If you just connect the main connector to your charger, then your charger does not have the balance function. When using the main lead your charger is only able to read the overall voltage of your battery and not the individual cells so its critical that you check these with a volt meter, or battery monitor to avoid any potential issues with you battery. You can also purchase separate battery balancers to ensure the voltages of each cell are correct, but these are very uncommon nowadays.

Some chargers like the one included with the DJI Phantom 3 many not appear to be a balance charger, but that is because the phantom 3 battery actually has a built in battery monitor and balancer built into it.

Cell compatibility
When buying a charger you should consider what LiPo batteries it can support. Some very cheap lipo chargers will only support 2S or 3S lipos, where the fanciers ones will be able to support the full range from 1S to 6S. Other higher end chargers are also able to balance charge more than one LiPo at the same time.

Charging current
Most batteries specificy a maximum charge rate as 1C, 2C etc… however most chargers you specifiy the charge rate in Amps, so sometimes there is confusion between these two values. To convert your battery C charge rate to Amps you simply need to multiply the battery capacity by the C rating. So lets say we have a 2200mAh battery with a charge rate of 2C. So the maximum current we can charge this battery at is 2.2Ah x 2 = 4.4A. Similarly lets say we want to charge a 5100mAh battery at 1C, the max current we will need to set on our charger is 5.1Ah x 1 = 5.1A. The maximum current you can for your charger depends on the power output it is cable of as described in the next section.

Power Output
All batteries have a certain power output level, defined in Watts, typically around 50W. This number represents how much power the charger can provide to your battery, ultimately the larger this is, the faster it can charge your battery. Watts are the product of current and voltage, so if you keep current constant (say at the recommended 1C value) you will use more power with higher voltage (bigger cell count) batteries. So having more power available it better. Lets look an example, if we want to charge a 3S 2200mAh battery at 1C we will need to use 12.6V x 2.2A = 27.72W. If we want to charge a 3S 5100mAh battery at 1C we will use 12.6V x 5.1A = 64.26W which is actually a little over the standard power rating for chargers. So we an only charge our 5100mAh battery at 50W/12.6V = 3.6A assuming we have a 50W charger.

Power Supply
Some batteries include a built in power supply so you dont need to worry about this. But if your battery does not include a power supply you will need to make sure that the one you buy will match your charger in terms of specifications and also the connector is the same. At Unmanned Tech we have the option to add a compatible power supply on most of our chargers.

However the most important thing is to ensure that the power supply has the correct power (Watts). So if using a 50W charger, you will need to make sure your power supply will be able to provide at least 50W of power to the charger, however getting something a little over is best such as a 60W power supply.

a 60W power supply is the most common type of power supply you will need for your charger


The process of charging a battery

Although each brand of charger might have different features, I will discuss the main ones that are shared with all Lipo chargers so you can have a basic idea of how to use them. For full details its best to read the documentation included with your charger. Some simple chargers just require you to connect them and it will start charging automatically.

  1. Plug in the charge and balance leads between your charger and battery.
  2. Select the appropriate LiPo balance charge mode on your charger.
  3. Select the appropriate cell count voltage and charge rate (1C recommended) (as discussed previously).
  4. Start the process and make sure you dont leave it unattended during the charge process

In terms of the technical details of charging most chargers follow a two set process. The first process (constant current) is when a constant current is applied (at the rate you specified) and keeps that current flowing into the battery until a certain voltage is reached. After this threshold the charger will switch to constant voltage mode where the charger will vary the current to make sure all of the cells have the same voltage (the balancing step). As the cells get close to the maximum charge of 4.2V the current will drop slower until eventually stopping at 4.2V per cell

Fast Charge
Some chargers have a fast charge feature which in my opinion is more of a gimmick than a useful feature. Fast charge allows you to save abit of time when charging your battery as it will skip the balancing step. In fast charge mode the charger will only look at the overall voltage of your battery and will stop slightly below the maximum charge for safety reasons (as the battery might not of been perfectly balanced at the start of the charge). This is only usefull if you want to get flying int he air, but in reality this does not save much time over a proper balance charge so to get the most life out of your batteries its best to always use the balance charge.

Battery Storage

Another useful feature that some chargers have is the Lipo storage mode. If you remember from your Lipo battery guide, its best to store your battery at about 40% to 50% charge. So the storage mode on your charger will automatically charge/discharge your lipo to this range in each cell so you can safely store your battery when you are not going to flying for a while.

What I normally do is after a flight, if I know I am not going to fly for a few days I will use the storage mode on my charger to half charge the batteries. Then when I know I am going to fly again I will fully charge the batteries before heading out to go flying.


Other usefull equipment

Here are complementary equipment that you should have in your drone toolkit.

Battery Monitor/Alarm
A battery monitor is nice and cheap device that you plug into the balance leads of your battery. They are set to beep when the voltage of your battery gets low so you know to come and land. But some like the battery alarm pictured below include a display that will show you the voltages of each individual cell, as well as the overall voltage of your battery which makes it a very quick and convenient way to check your battery voltage before going out to fly.

Digital Multimeter
Since most drones are electronic devices, having a multimeter is a great resource to help debug problems etc… They are actually not that confusing to work and its a great resource is check your battery cell voltages, and testing for cold solder joints. If you are not sure how to use one, check out the video in our how to use a multimeter guide

Lipo Safe bag

These are fireproof bags that you can use to safely store and transport your batteries. Always better to keep things safe


Any questions or comments?

I hope that you found this guide of some value, but if you have any questions just ask them below and I will be happy to try and help :-).


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#2

I have an iMAX B6 mini (SKYRC) and I have a daft question, how do I know when it is done charging, discharging and storage mode? Will it beep or something?


#3

Hi, with the b6 it will play a beep time once it’s complete and the timer should stop. To be honest I cant remember the last time I looked at the screen as I always just unplug the battery after I hear the music tone.


#4

Hey Thanx for the info above.
I need to know that… Can we charge 6s/5s lipo battery with a 3s charger??


#5

No, you will need to get a charger that has 6 balance ports for a 6s lipo


#6

Can I not use PQ Adapter Conversion Board W/ POLYQUEST CHARGER PLUG??
the link is give : http://robu.in/product/pq-adapter-coversion-board-w-polyquest-charger-plug/


#7

No that will not work if your lipo charger does not support 6 cells. The charger needs to monitor the voltage of each cell in your lopo, otherwise over time the you could end up over charging a single cell and damaging your battery, or worse, causing it to explode :boom:


#8

How about LiFePO4 battery packs? I read some say it’s not recommended to balance charge LiFePO4 battery packs, it’s better to simply charge it in series straight away, and I find that most LiFePO4 packs come without balance connector, but on the other hand, I also find chargers that capable of charging LiFePO4 usually claiming it can charge LiFePO4 balanced. I am quite confused, please shed some light on this :slight_smile: Thanks!


#9

I wouldn’t say it’s recommended to not balance lifepo4 batteries, but because the chemistry is much more stable in these batteries compared to lipo’s batteries you don’t really need to care about balancing each cell in the battery. In general there is little reason to use lifepo4 batteries for multirotors as the energy density of lipo’s is much more. Lifepo4 are better for power tools where you don’t care so much about weight, but more about power as lifepo4 have better power density.

Hope that helps


#10

Thanks for providing this information.

A lot of people who go out and buy a drone (me included) discover the battery issues and mysteries and all the wires and baby-sitting needed for the LiPo batteries are akin to looking for the Seven Cities of Cibola.

We buy a drone, use the charger that came with the purchase and suddenly we stumble upon all the info that they can explode, catch your house (or neighborhood) on fire, and that we need to buy special bags in which to store the darned things, discharge them if we won’t be using them for a couple of days.

And to make it even more complicated, we need to hook up a mess of wires and in some cases solder terminals on the ends of them and route the wires from the new balance charger/discharger (aka baby-sitter).

Years ago I actually built a real airplane (took 2 years) and installed the fuel system and valves, the avionics, electronic ignition, installed the engine, transponder and when it was all done, hauled it to an airport and made an appointment for an FAA inspector to come and inspect it. After he approved it, I then had to fly it!

Years later here I am with a drone, and as my brain has aged, I’m thinking "what the devil are all these darned wires for and where do they go, and you have to buy a different charger than the one that came with the drone? And you gotta hook up a USB cable from the charger to your computer? And you gotta balance the batteries? And before you go fly the drone, you have to do the “Macarena” in order to calibrate the compass? Heck, in all my airplanes I’ve owned (5) I did a compass calibration once per year (during annual inspection) and it was easier in my airplane than doing it for my drone.

Oh well, sorry for the rant… I’m off to Amazon to look for a charger/balancer/discharger as you have mentioned here in you really good article…

(People buy cars with automatic transmissions these days to simplify driving. I want a drone that “baby sits” the battery, calibrates the compass, avoids trees, can bring me a pizza and walk my dog… and maybe patrol my house when I am gone… :laughing: and not catch my house on fire…)


#11

:slight_smile: Thanks for sharing your perspective and also very impressive that you built your own plane! Got any photos to share? Definitely something I would like to do one day, but for now I have do make do with drones! I suppose part of the confusion is that most of the drone components use smartphone sensors and electronics which are considerably cheaper than something certified as aviation electronics. You say you only calibrated your aircraft compass once a year but I bet your compass sensor cost alot more than $5 which is probably why it only needed calibration once a year! But each year sensors are getting better and better and the software is also getting better, with the arducopter software for example, the compass is constantly re-calibrated as you are flying to deal with interference from motors etc…

I did not mean to scaremonger about the batteries, but its always better to be safe as I am sure you heard about the samsung s7 battery issues. Because we want the biggest capacity battery at minium weight this is what we have to live with for now. I even remember the Boeing dreamliner has some problems with battery instability in early testing!


#12

Hi can I charge my 5500mah 3s 35c battery with my old imax b3 charger?


#13

yes you can, might take a while but b3 charger works with any 2S or 3S lipo


#14

I’m using an iMax B6 Mini with a parallel charge board for my 6s batteries. Question: can I also discharge/storage mode multiple batteries with the parallel board?


#15

Hello

I have iMaxB6 Lipo Charger
I am using it to charge my 3cell Lipo

The problem is that on Display it is showing 23.6V as battery voltage when checked through meter the batter voltage is 11.1V
Kindly help me to fix this problem


#16

In general it will be faster to store.balance the batteries one by one rather than using a parallel board. But parallel board is still useful if you want to charge multiple packs in one go.


#17

What is the cell count of your battery? as that does sound very strange indeed. Are you sure you have a genuine Imax B6 charger as there are loads of fake ones on the market still which simply dont work very well.


#18

The cell count of battery is 3

Yes its the genuine one
It was working fine but suddenly this problem has occured.


#19

Hi, as I am new to Lipo batteries this article was extremely helpful, thank you. I keep reading on forums that it is a good idea to upgrade the cheap OEM chargers but the standard cheap one I have does the job I need it too, as long as I plan ahead lol. It connects via the balancer lead and charges both 2s and 3c batteries.
As it does everything I need it to, is there any good reason to upgrade it as recommended?


#20

Awesome article on lipo chargers! Thank you for emphasizing and putting first the never leaving the batteries unattended. I have heard so many horror stories about this! The pictures were awesome and descriptive!

I have my own guide on lipo battery chargers here if you want to check it out here.