Choosing the most suitable type of lithium rechargeable battery for each application is of paramount importance for individuals who use portable devices. After reading this article, you will know:
- What is Li-Po and the differences between Li-Po and Li-Ion
- Why Li-Po is so popular and it’s applications
- Safety tips for usage
- Chargers and protection circuits and parts
- How to make a charger circuit
Lithium rechargeable batteries are the most famous components used in portable devices. Li-Pos are a group of cells made out of four main parts. the process is transmitting ions between electrodes among electrolyte when charge and recharge is doing.
Li-Po is the subgroup of Li-ion battery and the main difference is in “shape” and this was because of a “structural” difference.
This difference caused to lighter weight products with different sizes and shapes and also more cost for manufacture, about 20 to 30 percent more than Li-Ion. Another difference is protection; a Li-Po can be used with or without protection but a Li-Ion can’t. In next parts reason will be explained but very summarized: lack of protection for a Li-Ion means explosion and for a Li-Po means in non-standard situation expand or toxic steams and damaging. Specifications of both are approximately same, the capacity of Li-Ion is a little more than Li-Po and because of metal shell it’s life span is more. Li-Ion is more sensitive to high and low temperature than Li-Po, it can’t work in these situations.
Let’s see this comparison in one sign, the reason of Samsung, Apple, Motorola and other mobile companies for choose of Li-Ion for most of their products will be clear: More capacity with lower cost. But lower safety in some cases like explosion in Samsung galaxy note 7 showed itself Similar problem in mobiles with Li-Po battery caused just expand. But don’t worry about explosion in your pocket! standards are more stringent after that problem recalls. But what was the problem?
Like everything else, it’s important to control situation for safe use. Both of Li-Po and Li-Ion should be protected against over-voltage, over-current, over-heating, very high or low temperature, charging too quickly, short circuit and stroke. Explosion may happen for both but in the case of Li-Po, its probability is very low.
- Don’t charge them when they are hot. Let them cool first.
- Check the charging current, it should fit to battery specifications.
- Use balance chargers for safe charging
- Don’t use them in very hot or very cold environments.
- Determine the GND before use in any circuit, it’s very important.
- When charging, put them in eye sign and check them.
Mobile, tablets, power banks, laptops and many other gadgets with voltage of 3.7 are made by li-ion. Just some of other gadgets and lots of devices are made with Li-Po; because in small size, more cells can make higher voltages. One of the familiar uses of Li-Po multi-cell batteries are RC (Radio control) devices, like quadcopters; which need high capacity, high current and high discharge rate. To make the best choice of battery for every use, specifications of the battery is important, so come to get know them.
The item that makes Li-Po comfortable for RC applications is C or discharge rate. In a simpler way, with this factor you will determine the speed of battery is what you need or not. For better understanding “speed”, think about a watch. Watches use battery very slow because they don’t need a big amount of current in any moment; but a quadcopter or robot or even a GSM needs at the start moment of their function use more current, so they need battery that can supply it. So what’s the best one for you?
We have three types of Li-Po/Li-Ion: high-energy, high-current, high-safety. from Ohm law we can find out more internal resistance made lower current (the discharge rate is depending on this feature); high-energy types have big internal resistance and high-current one has lower internal resistance to make high discharge rates, which is important in RC uses. For best understanding, mobile phone batteries are High energy (small with low current and high capacity) but a RC car is High-current.
First of all, calculate your voltage and current needs. pay attention to maximum current moments and the size of device that needs battery, too. Your minimum time of each use and the average current device needs will show capacity you want. Higher peak-current need more C, higher voltage needs more S. now you can select what you may need.
Now if you want to use a Li-Po, you would need a charger.the parts we will need for Charge are two connectors: JST for balancing and T for high current. High current connector, the way of charge via voltage and recharge to use current but the balance is the way for “safe” charging. in the charging process, it will be start from one cell. The first cell is completely done and sometimes more than what should be so other cells would be over-charged and finally the battery is unusable at all. What balancing can help is to charge all cells at the same capacitance so please use balance chargers for multiple cells Li-Po.
Another famous Li-Po charger is Imax B6 AC. Unlike previous charger, this charger has setting for modes you can choose. In addition to the Li-Po, other batteries like some of nickel-based rechargeable batteries can be charged with (check the correct battery type before charging). voltage and cell should be selected, too.
Another way of having a charger is to use charger modules. Different chargers are in shops but what we have here, is a 1-2S Li-Po charger. The “SET” jumper is to solder if you need 2S mode. This charger is not balanced but via an Arduino or other controllers you can control it and have different projects. as an example here we have one test circuit for our module:
Now we know Li-Po but the world of batteries and their adventures is bigger than this article. So if you have any question or interesting experiences share it with us. We will do our best to find the answer for you and to know more together.