How to Properly Charge a Drone Battery? A Comprehensive Guide

Drone battery charging is one of the most overlooked yet crucial aspects of the flight experience. Have you ever had a battery bulge or a sudden drop in battery life due to improper charging? In this article, we'll explain the charging techniques you can use to extend the life of your battery by 30% or more.

Understanding Types Drone Batteries Characteristics

Hidden Risks of Lithium Polymer Batteries (LiPo)

LiPo batteries have the advantage of high energy density, which allows drones to store more energy in a limited space for longer flights. However, it also comes with some hidden risks. For example, a pilot's failure to use a balanced charger resulted in a 0.5V difference in voltage between four groups of cells, which eventually caused the battery to swell. This is because Li-polymer batteries consist of multiple cells, and if the voltage of each cell is not balanced during the charging process, some cells will be overcharged while others will be undercharged, which will lead to battery damage and even safety issues.

In addition, for racing drones, batteries with a discharge rate above 35C are usually chosen. However, when discharging at high loads, the battery will generate a lot of heat, and at this time, you must remember to match the cooling fan. If the heat is not dissipated in time, it is easy to cause thermal runaway, leading to battery fire or even explosion.

Lithium-ion Battery (Li-ion) of the Reverse

Li-ion batteries are also widely used in the field of drones. Taking DJI Mavic 3 Industry Edition as an example, according to the winter test report of Extreme Flight Technology, the battery life can be increased by 22% by warming up the battery to 20°C in a -10°C environment. This shows that lithium-ion batteries are more sensitive to temperature, and in low-temperature environments, their performance can be significantly improved through proper preheating.

There are also some tips for storing lithium-ion batteries. When the battery is not used for a long time, you can use a rubber band to tie the battery contacts, which can prevent metal oxidation caused by poor contact. Once the metal contacts oxidise, it will affect the charging and discharging performance of the battery and reduce the life of the battery.

Drone Battery Charger Selection Guide

Life and death comparison of three types of chargers

Different types of chargers are suitable for different scenarios and also have their own taboos.

USB charger: When travelling in an emergency, a USB charger can solve the urgent need. However, do not use a fast charger, a brand of Spark has caused the motherboard to burn out due to the use of 65W fast charger. This is because the drone battery has strict requirements on charging current and voltage, and the high power output of the fast charger may exceed the battery's tolerance range, thus damaging the battery and even the motherboard.

Balance charger: For professional work, the balance charger is a good choice. Tested by DJI smart charger, it is able to automatically identify soldered battery cells, and the detection accuracy is 40% higher than traditional equipment. The balance charger can ensure that the voltage of each cell of the lithium polymer battery is balanced, effectively avoiding battery damage caused by inconsistent cell voltage.

1. Car charger: Car charger can play an important role in field survey. However, before connecting to the cigarette lighter, it must be noted that when the voltage fluctuation exceeds ±0.5V, it should be stopped immediately, and it will be safer to install a voltage regulator module. The voltage of the car circuit is sometimes unstable, too high or too low voltage may cause damage to the drone battery, the voltage regulator module can play a role in stabilising the voltage and protecting the battery safety.

Drone Battery Charging Full Process Specification

There are five-step safe charging method for your drone batteries.

Pre-testing stage: Before charging, use a multimeter to measure the resistance of each contact, and according to the FAA maintenance manual standard, more than 0.2Ω needs to be cleaned immediately. Excessive contact resistance will affect the charging efficiency and may also lead to poor contact and cause safety problems.

Environmental control

When charging in summer, it is recommended to place ice packs in the air-conditioned room to cool down the temperature and control the ambient temperature at 25±3℃. Battery charging at the appropriate temperature can extend its service life, too high a temperature will accelerate the aging of the battery.

Charge Monitoring

When using fireproof bag, leave 5cm space for heat dissipation. There have been cases where the temperature inside the bag soared to 80℃ due to airtight storage, which would cause great damage to the battery and even lead to fire. Leaving space for heat dissipation can ensure that the heat generated during the charging process can be emitted in time.

Post-processing Stage:

After charging, the battery should be left for 15 minutes before use to avoid sudden load damage to the battery cell. The internal chemical substances of a freshly charged battery are not yet fully stabilised, and immediate use may cause irreversible damage to the battery cell.

Abnormal handling

When you smell the sweet odour (electrolyte leakage), immediately put the battery into the sand box, which is a more effective emergency measure than the fire bag. Electrolyte leakage is a very dangerous signal, the sand box can effectively prevent the battery from further combustion or explosion.

Three Ways to Prolong Drone Battery Life

Battery Warming Black Box

Put the battery into a thermos cup and fill it with 40°C warm water, it will recover 80% of its activity in 10 minutes. But be careful, before removing the battery to use, you must completely dry the water, otherwise the water into the battery will cause a short circuit and damage the battery. This method can quickly increase the activity of the battery in a low-temperature environment, increasing the endurance of the drone.

Charging Battery Magic

Using the PD protocol decoy, the output of the 20000mAh rechargeable treasure can be adjusted to 16.8V to achieve emergency replenishment in the field. However, this requires circuit modification qualifications, because private circuit modification may cause short circuits, fires, and other safety problems if not operated properly. In this way, the drone battery can be replenished in the absence of a conventional charger in the field.

Solar Charging

With the MPPT controller, the charging efficiency is 37% higher than that of a regular charger in highland areas. Solar charging is an environmentally friendly and convenient charging method, especially suitable for long hours of operation in the field, and the MPPT controller can maximise the charging efficiency of the solar panels to charge the drone's battery quickly.

Common Misconceptions

Rumour: New batteries need to be charged for 12 hours to activate

DJI official statement: Smart batteries are pre-activated at the factory and can be charged up to 100% for the first time. Nowadays, smart batteries have been pre-activated at the factory and do not need to be activated and charged for a long time like NiCd batteries in the past. Overcharging is not only a waste of time, it can also damage the battery.

Rumour: Charging immediately after a flight saves time

According to UL Labs, charging a battery at temperatures above 40°C reduces cycle life by more than 50 cycles. Charging immediately after a flight, when the battery temperature is usually high, will cause the internal temperature of the battery to rise further, accelerating the aging of the battery and shortening the cycle life of the battery. Therefore, it is recommended to charge the battery after the temperature has dropped to a suitable range.