RC Battery pile

About RC Batteries.

The purpose of this article is to introduce you to two most popular types of batteries in our hobby, along with giving you basic information about the limitations and advantages that can come with using each type of them.

A quick disclaimer before we start. I'm only able to provide the advice based on my experience, general and manufacturers safety guidelines. Please remember, you are the person responsible for your own safety.

Having this out of the way,  let's start our take on:

Lithium Batteries.

Let's first talk about the power source a little bit. The two most popular types of batteries used on RC planes are, in order: LiPo (Lithium-Polymer) and Li-Ion (Lithium-Ion) Batteries. Both types have it's specific advantages. It is mostly down to the compacity and the ability to discharge quickly with the high current rate.

LiPo (Lithium-Polymer) batteries are the most commonly used power source for the RC flying models. This is quite unsurprising and easy to see why. They are able to provide the best power-to-weight performance and highest discharge rating. It also means the will not be experiencing the voltage drop under the heavy load! This is specifically the reason why the LiPo batteries are so common on the most powerful builds like the racing drones.

Li-Ion (Lithium-Ion) Batteries, on the other hand, are more capable if comes to the long-range builds. Due to the ability to discharge below the 3v per cell. Li-Ion batteries are also not very useful on highly demanding and power-hungry setups. This is due to their, low discharge ratings comparing to the LiPo packs.

By the way. The electric power-to-weight ratio is sometimes called power density. Just so you know.

LiPo (Lithium-Polymer) batteries - Specification:

The voltage parameters for Lithium-Polymer (LiPo) batteries are as below: 

  • Nominal voltage: 3.7v per cell.
  • Max charged voltage: 4.20v per cel = 100% charge
  • Land at about : 3.70v per cell = 20% charge
  • Critical / Land Now voltage is: 3.20v per cel
  • Resting/storage voltage : 3.80v-3.85v per cel
  • Discharge ratings ( average range ): from around 50 to 120 x Compacity in Ampers.

Oher, imported information: Optimal operating temperature for LiPos is 30-38°C and it can affect the compacity as much as 50% depending on the individual battery build and performance when it gets really cold! The general range of the temperatures for lipo batteries advice by most brands is around: Max ~60°C and Min ~10°C but it is possible to use them outside of this range however please keep in mind you are risking fire if you allow overheating or significant drop of compacity if you are using LiPo batteries below this temp range.

Li-Ion (Lithium-ion) batteries - Specification:

The voltage parameters for Li-Ion (Lithium-Ion) batteries are as below: 

  • Nominal voltage: 3.6v per cell.
  • Max charged voltage: 4.20v per cel = 100% charged
  • Minimum voltage: 2.8v per cell
  • Resting/storage voltage : 3.80v-3.85v per cel
  • Discharge ratings ( average range ): from 10 up to 30 Ampers.

Oher, imported information: The use of a lithium-ion battery is possible in a temperature range of 10°C to +55°C. However, the charging should take place only at a battery temperature of +5°C to +45°C. The ideal temperature range of the batteries is room temperature.

Lithium battery fire is no joke!

No kidding! This is a real threat and you should not underestimate or ignore the danger! Lithium batteries don't matter which type,  might be dangerous and cause a fire if stored or used improperly.


lipo explosion lipo fire

Here is the short list of what you should never do:

  • NEVER CHARGE THE DAMAGED BATTERY
  • Do not store fully charged lithium battery for more than 1 max 2 days! Keeping fully charged lithium batteries stored is not only pushing your luck. They are degrading very quickly in this sort of situation. Causing rapid drop in capacity and usability. It's strongly advised to use them as quickly as possible after they were charged.
  • Do not overcharge your batteries! It's true that some lipo batteries can handle Max voltage of 4.35v per cell but I strongly discourage you from getting above manufacturer limits!
  • Balance and charge your batteries to storage voltage before putting them away. Keep an eye on them if you are not planning on using your batteries for a longer time. Regularly look for any signs of swelling or a licking etc.
  • Do not charge if any of the battery cells has dropped below critical voltage! especially if it dropped to 0 volts! If it's dead, it is dead!
  • Always read the manual!

An example of the swollen (Puffed) lipo cell on the left:
puffed lipo cell

An example of the swollen (Puffed) lipo cell on the right:
puffed lipo

 

Storaging lithium batteries.

Storaging lithium batteries might be a challenge. From my own experience, it is usually the best to use thick metal containers like, for example, empty ammunition boxes.

Li-Po storage ammunition box

Disposing lithium batteries is a complicated and dangerous process... Please remember you cannot just throw them away.  If your battery was damaged, showing signs of swelling on one or more cells,  has been punctured or bent,  or smells funny ( not kidding, Damaged battery do stink sometimes, just take my word for it and let's hope you will never have to experience it ). Before you throw it away you need to fully discharge your battery. 

The safest way I found to do it is to put the battery into salty water...  leave it there for a night. Salty water is a good conductor. It should suck all the energy out of the battery of the night,  and the liquid around will provide good temperature control. But for obvious reasons please don't do it inside your house!

lipo in salty water

 

I guess that's pretty much it.  please remember to keep your batteries well maintained and they will serve you for a long time. 

Treat them with respect and they will not cause problems or nasty surprises

Thank you for reading my article, please leave the feedback via the link below if you have found any errors. 

All the best and stay safe.

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