Most, if not all drones used in STEM education use lithium polymer batteries. These batteries offer great advantages over other types to include high power and fast discharge rates. But these benefits come with some strings attached. Proper charging, use, life cycle, maintenance and disposal are all thing instructors need to know about as they introduce exciting aerial robotics into their school of STEM Camp.
Lithium polymer batteries, called LiPo’s require a charger made for them. LiPo’s have polarized power leads and a balancing cable. Both need to be connected to fully charge or discharge them. The main power lead is mated and can only be connected one way. This is a great safety feature that keeps anyone from reversing the polarity and shorting out the battery. The balancing cable for a 3-cell battery has a 4-wire connector that is also polarized. The balancing cable, as the name implies, ensures the voltage is balanced across all cells.
LiPo batteries offer a lot of power and that is necessary for multirotor drones to get off the ground. That said a short circuit, damage from a crash or, more commonly, misuse can cause the battery to burn. Placing the batteries in a low-cost LiPo protective charging bag is a great practice for both charging and storing these batteries.Overcharging and over discharging are the things that can lead to a fire.
Guidelines for Safe Use in the Classroom
- Before using or charging the battery you should look at it to make sure it does not have a puncture. These can lead to short circuits and a possible fire. If you drone has a bad crash (not uncommon when students are learning to fly) make sure you check the battery for damage and if you find any don’t the battery and make it for disposal.
- Like all batteries, lithium polymers have a limited life cycle. In heavy use, that is, repeated charging and discharging, take a toll on the chemicals that make the battery work. So here are some best practices for long battery life. When charging the batteries always use the balancing cable. Don’t keep the batteries fully charged until you need them. A fully charged battery that sits for a long period without being discharged can deteriorate the chemistry.
- Most chargers have a “Storage” function, charging them to that level between uses can extend their life. Many educational drones have a feature that emits a signal (an LED or audible alarm) when the battery is getting low. It is best to land the aircraft and change out the battery rather than continuing the flight and draining the battery further, this will also extend its life.
- When a LiPo battery starts to expand, and get “puffy” it time to dispose of them. To do this you should fully discharge the battery first. Many charger have a “Discharge” function but you can also take a plastic bucket, add warm water and salt and place the batteries inside. This will slowly discharge the batteries safely as well. Many consumer electronics stores like Best Buy of Radio Shack have battery disposal bins.
The modern multi-copper would not be very capable if not for the innovation of the lithium polymer battery. Knowing how to use, charge, maintain and dispose of these batteries safely will ensure a great safe learning experience.
For more on the use and management of batteries for your drone education program you can watch our Drone Ranger™ video on You Tube.
And you can see our complete line of Drone Ranger™ Education Kits and accessories from OnPoynt Aerial Solutions at our website TheDroneRanger.com.