The battery cooling system by dry ice

The battery cooling system by dry ice
The battery cooling system of the MotoE

In an electric motorcycle, when the battery temperature rises above the optimal limit, the available power drops from its maximum value. For this reason, in 2020, Energica had developed a cooling system to lower the internal temperature of the battery while riding on the track. This allowed all the riders to have the maximum power of the bike for the entire duration of the race, regardless of the ambient conditions and their riding style.
The battery cooling system, introduced by Energica last year, allowed to race regularly in Jerez despite the 37°C air temperature. The system serves to convey fresh air to the battery while the bike is on track but also to cool the battery when it returns to the pits before recharging it. This operation involves 'blowers' that take air from the environment and convey it into the battery. This avoids reaching the maximum temperature threshold of the electric cells and at the same time extends their life. The air, purified by a filter that retains impurities and humidity, is sent directly into the battery to cool the connections between the cells, which are the hottest part.

The cooling of the battery of the MotoE in the pits

In the first official test of the MotoE 2021 in Jerez de la Frontera, in March, Energica had brought an additional system to cool the battery of motorcycles in the pits, when the climatic conditions are extremely hot. Giampiero Testoni, the CTO of Energica, explains here in detail the operating principle of the new system:
"This idea came from the fact that, during winter testing, we want riders to do as many laps as possible during the three sessions per day. With fast charging and the actual riding on the track, it can happen that in the last session of the day, a situation of power limitation by the bike can be triggered. Therefore, we decided to implement a system with dry ice; we firstly created a test system, and we made some trials with different configurations: different type of systems (open/closed, fan/blower), while simulating battery heating – and keeping track of the temperature. In the end we chose the one that we reckon was more fitting to the situation.
This system is simple: it is basically a thermic box containing dry ice: our Makita blower blows air through a tube into the box, and, with the dry ice, the air temperature decreases considerably an in a very short time. The cold air is then sent out to the bike through another tube and the cooling process begins."

The dry ice cold box system

After the first test in Jerez, we saw that there were things that could be improved, so we made a modification to the system. What we noticed last month was that with higher humidity levels, some ice was forming on the intake grid of the battery. Obviously, with the temperature of the air being around -15/-20°C (5/-4°F) a sort of ‘wall’ of ice was formed. That meant that we had to wait for the ice to cool down before resuming the procedure.
For the test in April, we have added an intermediate filter and decreased the flow of the blower, which should prevent any formation of ice and therefore allow us to use this system no matter the humidity levels.
This system will also allow to keep the battery in the ideal temperature especially in the racing weekends that are marked by extremely high temperatures (as experienced last year in in Jerez): it will be possible to cool down the battery before the race, and that will also make it easier should the need of three sessions on the same occur during an official MotoE event."

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