Beginners Guide To LiPo Batteries - FPV Freedom Coalition

The usable voltage range for a standard lipo battery cell is 3.2v to 4.2v. Any lower than 3.2v and the battery may be permanently damaged. Any higher than 4.2v and you significantly increase the risk of a battery bursting into flames. Normally you will start with a battery cell that is at storage charge or 3.8v, place it on the charger, let the charger charge the battery to 4.2v, then go fly until the battery cell voltage drops to somewhere in the 3.5v to 3.7v range depending on how nice you want to be to your batteries and your comfort level. You might ask, why not fly until they are all the way down to 3.2v? Well, you can, but that puts additional strain on the batteries, shortens their life a little bit, and typically when you fly and give the drone a burst of throttle, the battery will sag and the voltage will drop as it tries to provide all the power it can. If this sag causes the battery cell to go below 3.2v, it will cause more damage. Also many drone batteries are created from multiple cells and you don't always know the exact voltage of each cell. If you have a battery created from 6 cells, they won't all discharge at exactly the same rate and you could end up with one cell at 3.0v and others at 3.4v. In that case you risk damaging a cell or the entire battery. So that is why the recommendation is to land when your batteries are at 3.5v per cell or greater. You may also notice that after you land and give your batteries a few moments to recover from their hard work, the voltage will recover slightly and your 3.5v battery cells may stabilize closer to 3.6v or 3.7v per cell. Some people will even stop flying at just the right time such that their batteries are at 3.8v per cell so they won't have to storage charge them when they are done. You get less flight time this way but it might be worth the trade off to you.

Battery Cells

Drone batteries come in all sorts of shapes, sizes, cell counts, connector types, and more. Everything from a very small single cell battery for a "Tiny Whoop" to a large 6 cell battery often used in drones with 5" propellers. ( Yes, they do come larger than 6 cell varieties, but if you need one of those this guide is probably not for you. ) When you add multiple cells together to create a bigger more powerful battery, the voltage of the entire battery is multiplied by the number of cells. For example a 4s battery, which contains 4 lipo cells in series, would have a maximum charge of 4.2v x 4, or 16.8v. A 6s battery would have a maximum charged voltage of 25.2v. And the more voltage you have, the faster an electric motor will spin. Which is also why it is important to pair the right rpm motor with the right battery voltage. But we will leave that for another guide. The important part here is to understand the relationship between voltage and cell count. I would also recommend having your OSD display the average cell voltage in your FPV goggles. That way it won't matter if you are flying with a 4s or 6s battery, either way it will show you the average cell voltage and you will get used to using that value to decide when to land.

You may also see a battery listed as 4s2p, or 2s2p. That is just letting the buyer know that there are some cells in series and some cells in parallel to create the voltage and capacity necessary for the overall battery. So in the case of a 4s2p it lets you know that there are 4 cells wired in series each made up of 2 cells wired in parallel for extra capacity without increasing voltage.

Any lipo battery made from more than one individual cell has the potential to have the cells become out of balance. Ideally you want all the cells in a single battery to be at the same voltage at all times. To help you achieve this, your lipo charger has a charging option called "balance charging". Some chargers will also split the charging up into "fast charging" and "balance charging" phases where they will first quickly charge up the cells to something close to fully charged, and then slowly top them off while checking the voltage of each individual cell to make sure they are all equally charged when finished. For maximum health, you should always balance charge your batteries. This is also why your 2 cell or greater LiPo battery has a second plug on it. This second plug is called the balance plug and is used by your charger to individually monitor and balance charge each cell.