Research commissioned by Heliguy shows that low storage temperatures can have an adverse effect on the performance of drone batteries.
Power levels drop significantly, particularly in the first 5 minutes of flight. In partnership with the Business and Intellectual Property Centre, Heliguy (Colena UK Ltd) asked Northumbria University to test the effects of extreme environmental temperatures on battery storage and discharge.
The research was divided into two stages. 1) the effects of temperatures between -10 degs C and 40 degs C on the stored charge and 2) how the same storage temperatures affect the rate of discharge when a drone is flying. Both stages were divided into two sections with the new, four-cell lithium polymer batteries in parallel being exposed to different storages temperatures for a short, two hour period and a longer, 12-13 hour period. Drones supplied by Heliguy are used by a wide range of operators who use their aircraft in extreme conditions such as wind turbine inspection, cold storage work and geographical mapping. Although the research revealed no loss of battery charge when stored for both durations at lower temperatures, the colder temperatures did speed up the rate of discharge in flight, particularly during the first 5 minutes.
Heliguy's battery discharger used to simulate flight conditions. At or below zero degrees this could lead to significantly shorter flying times and that could catch out an inexperienced pilot. Cold conditions can also lengthen the time it takes to charge a charge a battery and may, if it becomes a regular occurrence, shorten the operational lifetime of the power pack too. So the report recommends that batteries are not exposed to very cold conditions prior to use and that an ambient temperature as close to 20 degs as possible, but certainly above zero, should be maintained for best battery performance. Where cold temperatures can't be avoided then insulated storage and transport of batteries should be considered. Warming batteries and then keeping them warm when they're flying is also an option. DJI has come up with these two options for the Inspire 1.
The first is a battery heater
, which brings the power pack up to optimum temperature before flying. The second is insulating stickers which go on the outside of the TB47
batteries to help them to retain heat when operating at temperatures below 5 degrees C. Different size stickers are available for each battery.
Drone batteries under test in Northumbria University's environmental chamber. The research at Northumbria University was conducted in an environmental chamber normally used for testing human performance in extreme conditions. It was carried out by Dr Martin Barwood, who's a Research Fellow in the Department of Sport, Exercise and Rehabilitation at the Faculty of Health and Life Sciences. “We found that the drones and their components stand up to the extremes of temperature in which they are being used, which is excellent news," says Dr Barwood. “However, they are still affected when the temperature changes – particularly when it gets very cold - so we are recommending a reduced flying time in extreme cold conditions. This new information will help safeguard the drone and could help reduce pilot error when the pilot is faced with bitterly cold conditions. “These initial tests have provided both Heliguy and ourselves with a platform to progress in this vibrant area of business and research.” Heliguy provided the batteries but also produced a bespoke discharger which simulated the demands placed on the power pack during typical flights conditions.