With effective battery thermal management your lithium battery pack performs at its maximum potential

Effects of temperature on lithium batteries

It goes without saying that battery pack thermal management is a critical functional aspect. The operating temperature of a battery plays a crucial role in its lifespan and performance, so it is wise to keep the temperature within the right range.

Too low a temperature can reduce the battery’s capacity; too high a temperature can cause degradation and as a result, a lower number of life cycles.

This is the reason why lithium batteries that encompass an advanced battery management system (BMS) and heating and cooling systems (where necessary) will ensure the machine operates at its optimum performance under any temperature and ambient condition without compromising battery life.

At Flash Battery, we build battery thermal management into the battery system. This ensures the correct operation of the battery pack under extreme conditions, such as in temperatures as low as -30°C or as high as +45°C, plus the life and efficiency of the lithium battery remain unaffected.

Types of Heating and Cooling Systems

Heating systems can be implemented in two different ways:

• With electric heating elements applied to the cells
• With a fluid circuit

Cooling, on the other hand, can be implemented in three different ways:

• With a forced ventilation system, to allow the exchange between the air inside the battery pack and the outside air.
• With air cooling system inside the pack
• With liquid cooling system inside the pack

The best solution from the listed choices will depend on the field of application, the stress on the battery pack and the expected mass production numbers.

The Heating System in Lithium Batteries

A heating system is highly recommended in a lithium battery designed for a hybrid or electric vehicle. At Flash Battery, we implement it in almost all of our batteries.

Why?

In order to avoid safety issues on the battery pack.

One of the limitations of lithium batteries is that they are unable to charge at a temperature below 0°C. In addition, if left at temperatures below 10°C, their internal resistance suffers, which causes the voltage to drop and, as a result, a loss in efficiency.

Fitting the battery with a heating system to ensure correct operation and consistent performance even in frigid temperatures is therefore very beneficial.

Thanks to the heating system, a vehicle or machine plugged in for charging can maintain the temperature of the lithium battery at, for example, 15°C, and be ready for use at maximum performance.

What’s more, besides having a low impact on the overall cost of the battery, the heating system allows you to leave the vehicle or machine outdoors regardless of the weather conditions.

The Cooling System in Lithium Batteries

The choice of whether or not to integrate a cooling system into a lithium battery pack is a bit more complex. A cooling system can be especially costly and will have a significant impact on the final cost of the battery. And actually, it might even be unnecessary.

For this reason, it is crucial to thoroughly study the operational requirements of the applications beforehand. As a rule, if neither short charging and discharging times nor multiple cycles in the same day are expected, then a cooling system is not necessary.

Take for example a road sweeper: it only works a few hours a day so a cooling system would not be an effective choice. In fact, if the battery is cooled but then the vehicle remains inactive for the rest of the day, the integrated cooling system would be useless anyway because the battery would remain exposed to the outdoor temperature for most of the time.

Conversely, a cooling system is a good choice for intensive use applications. The stress on the battery in these cases is very high due to numerous short charges and discharges, which contribute to an internal temperature rise.

Let’s use as an example the AGVs and LGVs working 24/7 in a logistics system based in countries like Morocco, Brazil and Qatar, which have particularly hot climates: without a cooling system the battery life in these vehicles under these conditions will be reduced drastically.

Which is the best solution for your vehicle or machine?

Each application has its own unique requirements. Before making an important decision such as the purchase of a lithium battery, be sure to place your trust in an expert manufacturer for competent advice on the features best suited to the vehicle or machine you are planning to electrify.

The working temperatures and ambient conditions, as well as the work cycles of the application, could prove to be decisive factors in choosing which system – heating or cooling – to use inside the battery pack.

The type of application, its consumption, size and weight, how it will be used, and the characteristics of the operational spaces and context are all essential elements used by our team when customising your vehicle electrification project.