Everything We Should Know About Li-Po Battery

Electric RC Toys has becoming more popular – especially the airborne type, since Li-Po battery invented. It has more advanced benefits which are helping to popularize the electric toys. One of them is the light-weight benefit, which is very suitable in flying remote controlled toys, like helicopter or airplane. The Lithium-ion Polymer battery can be obtained in the market starting at around 1996.

Li-Po is using dry electrolyte that looks like a thin plastic film, that is why this battery could be shaped very thin and light-weight but able to hold more power. Compare to the Lithium-ion (Li-ion) battery which is using a liquid electrolyte.

New Type of Li-Po Battery

Since 2009, the new type of Lithium-Polymer battery has been introduced, where it is using a gelled electrolyte. Some people call it a hybrid Li-Po battery. This new battery type has less possibility to leak, but still keeps its flammable potential, to burn or explode when overcharged or other mishandling act.

The hybrid Li-Po battery has an interesting trait, its ion exchange rate tend to get more efficient when it gets warmed up.

Li-Po Battery Ratings

If you read the label on the battery, you can see some sorts of technical term, which are the battery specifications. Read on for more information what to know when you want to buy a LiPo battery.

a. Voltage

Each cell in Li-Po battery contain 3.7 volts, compare to NiMH or NiCad which contain only 1.2 volts per cell. Sometimes you can find the battery with 1S or 2S written on the label, that means the battery contain 1 cell or 2 cells (S stands for Series), respectively. More cells means more power, for instance 10S Li-Po battery contain 10 battery cells with the total power 37 volts.

You will also find a label like 4S2P (P stands for Packs), that means the battery contains 2 packs of 4 series of cell. This type of battery will hold more capacity.

Please be careful in choosing your battery, read your rc toys manual, which kind of battery they need to operate properly. Don’t try to change it unless you know exactly what to do next.

b. Capacity

Capacity describes with a milliamp hours (mAh) unit, which means the power contains in the battery. In practical it means how much load can be given to make the battery fully discharge in 1 hour. For example; 1,000 mAh battery means it will be fully discharge in 1 hour if the load given 1,000 milliamps (1 A), that also means it will discharge in 15 minutes if the load 4,000 milliamps (4 A) or 4 minutes in 15,000 milliamps, and so on.

Therefore, if you want to play longer with your RC toys, please find the battery with bigger mAh. You can change without reading your manual, but the problem is when you want a bigger capacity, the battery will become heavier. Consider this when you want to get higher battery capacity, especially when you intend to use it on your airborne rc toys.

c. Discharge Rate

Discharge rate is the term to inform you how fast the battery discharged safely. You can find the discharge rate describes in C unit. If you see the 20C, it means the battery can be safely discharged 20 times more than the capacity, 10C means 10 times and so on.

You can calculate it by yourself by using this formula. Divide the capacity to 60, to get the capacity in minutes, and then multiply it to the C rating. Then divide the capacity with the results.

For example, 20C rating on 2,000 mAh battery, that means you can give 20 times more load equals to 40,000 miliamps and that would exhaust the battery within 3 minutes. Let’s see the formula : 2,000/60=33.3x20=666 mAh per minute; then to get the time divide the capacity to the result, which is 2,000/666=3.03 minutes.

Several Li-Po batteries give different discharge rating, that is Continuous and Burst. Continuous is the normal discharge rate (normal usage) and Burst means the battery discharge rate when under short burst of increase power. Example of this rating is 10C Continuous /20C Burst.

You could expect that more C rating means more expensive the battery will be. Purchase the largest C rating if you can afford it. As a guidance, for normal flying rc it is enough to get 20C-25C, for larger airborne supply it with 25C-30C, and if you are an aggressive player please use 35C-45C.

Li-Po Battery Pros and Cons

RC Li-Po Battery Advantages

• Light-weight and can be built in almost any shape and size
• High discharge rates
• Hold bigger capacity compare to other battery type with the same size

RC Li-Po Battery Disadvantages

• Volatile and easily burn or explode when mishandle (i.e. overcharge, punctured or shorted)
• An expensive battery than another type
• The battery life-span is 300-400 charge cycles, or even less if not cared for in the right way
• Battery life-span depend upon several things such as storage, charge and discharge

How to Handle Li-Po Battery

• Keep your battery’s temperature around 50 - 60°C when in use or in storage, hotter battery will shorten its life span. If you find out that the battery reach above temperature everytime you are using it, then you should buy another battery with higher discharge rate
• Prevent over discharge; never push your battery to use more than 80% of its capacity. For instance stop using your RC toys when you have used 1,600 mAh when you are using 2,000 mAh type of battery.
• Never charge your battery more than its capacity, for example 2,000 mAh battery should charge it at 2,000 mA or 2A current (or also known as 1C). But some batteries could stand to 2C or 3C charging rate, that means you can charge it twice or thrice its capacity.
• Inadequate charge balancing, find a good charger with charge balancing features or a single cell in your battery would possibly damage by over discharge when other cells still not fully charged.

I hope this article could gives a better picture about RC Li-Po battery, but if you want to know more about it, please read this resource. You can also visit my previous article about rechargeable battery's charger.