LiPo handling is very much important in order to safely use and store your batteries. In this article, I am trying to give you a good overview about what you should do so you don't have to be afraid of lithium batteries and can safely use them. If you do everything right, lithium batteries are safe.
Important: Safe voltage range for a LiPo cell is 3.0 volts min to 4.2 volts max
LiPo batteries can have a voltage per cell of 3.0v to 4.2v (v = volts). If one individual cell goes below 3.0v, they are very likely damaged permanently. This is one of the things you want to avoid if you want to safely handle and use LiPo batteries.
In reality, the performance of LiPos gets really bad below 3.3v-3.5v. For use in quadcopters, which are drawing a lot of current, a good rule of thumb is to stop flying above 3.5 volts per cell to be sure to avoid damage. If it is a battery used for Goggle which does not draw much power, you may be able to run them down closer to 3.0v.
One exception to that rule is batteries that are labelled with HV - high voltage. Labelled HV LiPos are rated to go up to 4.35v per cell.
Another exception are 18650 Li-Ion batteries, which can go down to 2.5v per cell.
What does 4S or 6S stand for and what is a safe voltage range?
6S stands for 6 cells wired in series. 4S thus stands for 4 cells in series. The effect of that is that the cell voltage add up. A fully charged 6S battery thus has a voltage of 6*4.2v = 25.2 volts per cell at full charge.
At full discharge, a 6S batteries has 18v (6*3.0v), however, you wanna keep it at 21.0v (6*3.5v). So land if the quadcopter if the battery gets towards 21v.
A safe voltage range for a 6S battery is thus between 21v and 25.2v.
- Never leave your charging batteries unattended.
- Never charge a battery without plugin in the balance connector.
- Try to always charge the batteries with 1C. Only charge with higher C ratings, when you know what you are doing. C rate refers to how quickly you are sucking energy / current out of the battery. Take the mAh of the battery and convert to amp and that amps is 1C. For example, a 5000mAh battery converts to 5A (5000 divided by 1000). So if you charge your 5000mAh with 5amps (=5A) you are charging it with 1C.
- Only charge at a place without anything flammable nearby.
- Immediately dispose of batteries that are puffed, have visible damage or are clicking while charging. If you want to know how to tell if a battery is damaged and needs to be replaced, watch this video from JB.
- You can use a metal ammo box to charge your LiPos. Watch the video below for more details. If you want the absolute safest way to charge your LiPos, then you want to get a BAT-SAFE. You can get them from Brack.ch and Digitec.ch.
For more information on safe LiPo handling watch JB's video on How to keep LiPos from burning down your house (safe lipo charging) down below: