Did you know that the Nissan Leaf and Volkswagen e-Golf lack active cooling of the batteries? Nissan has put restrictions on fast charging. Volkswagen dampens engine power if you drive too hard. It does not matter which solution is chosen to control the temperature. Read why!
The quality that is rarely mentioned
Modern electric cars should have systems that control the temperature in the battery cells. It is important for performance, for the batteries to take a fast charge, for range and for the life of the batteries. The factory numbers only apply when the batteries are at the correct temperature. The batteries prefer the same room temperature as us humans. Not all electric car models have satisfactory solutions. We have tried to find out which solutions are used in the most popular models. It's no easy task, even for car geeks.
Reverse Engineering
Car manufacturers prefer to present the battery packs as black boxes. They are generally reticent to provide detailed information. Even simple questions such as "Who produced the battery cells?", can be deeply embedded. It will then be much more difficult to find out how excess heat is conducted from the batteries under load, or how efficiently heat can be supplied on cold days. Fortunately, there are actors who make a living by picking things apart to document how they do it really is constructed, – the unvarnished truth. Cars such as Tesla 3, BMW i3, Opel Ampera (Chevrolet Bolt) and Renault Zoe have already been dissected.
Passive or active cooling?
Flat or round cells?
Worldwide, there are only a handful of manufacturers who supply the entire world with battery cells. The best known are LG Chem, SK Innovation and Samsung SDI in South Korea, BYD and CATL in China and Panasonic, originally Japan. The battery manufacturers only deliver celler and allows car manufacturers to build their own battery packs. The following types of battery cells are used:
Pouch cells
Almost all new battery packs today are based on flat cells wrapped in plastic - so-called pouch cells (also referred to as pocket cells or pouch cells). These can be stacked close together (but not for close) – and usually vertically.
Prismatic cells
Here, the cells are wrapped in more solid material, such as aluminium, which absorbs more heat than the plastic in the bag cells. The BMW i3 and Volkswagen e-Golf use this.
Round cells
Round cells are reminiscent of flashlight batteries. Used by Tesla, but Toyota uses/will use round cells as well. These can also absorb more heat than the bag cells.
Liquid cooling
Tesla 3
Opel Ampera/Chevrolet Bolt
Vertical bag cells from LG Chem. Separate cooling frame under the batteries with coolant channels controls temperature. For reasons of space, the battery cells are stacked with two layers at the back - as an extra elevation. It is uncertain whether the topmost cells get as good cooling as the cells closest to the cooling frame.
Audi e-tron
Jaguar I-Pace
Vertical bag cells from LG Chem. Liquid-cooled temperature control. Unknown how the channels run, but it is assumed that they are located under the battery pack and consist of several loops. Jaguar is reticent to publish detailed information.
Hyundai Kona
Bag cells from LG Chem. Active thermal management with liquid-cooled channels in a cooling plate under the batteries that transports away heat when needed. The system has several loops and its own cooler. The system can also produce heat when needed. NB! Only cars for the Nordic markets have a battery heater.
KIA e Niro
Bag cells from SK Innovation. Liquid cooling. Same system for thermal management of the batteries as the Hyundai Kona.
Models that have been upgraded from air to liquid cooling
Hyundai Ioniq
KIA e-Soul 64 kwh
Models from 2020+ have pouch cells from SK Innovation. Uses the same system for battery cooling and heating as the Hyundai Kona. The first series of KIA e-Soul – before 2020 – ventilates the batteries based on air from the car's air conditioning. They have their own fan to draw air if needed.
Active battery cooling with air
Renault Zoe
New 2020+ models with 52 kwh have vertical bag cells from LG Chem. All models (also older ones) have active air cooling that uses air from the car's air conditioning to supply cooled air directly into the battery box - one hole for intake and two for venting. During charging, the car can therefore start the air conditioning if necessary. The system can also use warm air from the heating system, for example during preheating.
BMW i3
Without active battery cooling
Nissan Leaf
Lying pouch cells from Chinese AESCs. Nissan claims that there is no need for active battery cooling, even for 62 kw batteries. Leaf has put a limitation in the software to limit fast charging several times in a row - on the same day. The phenomenon is hashtagged #rapidgate. This is probably done to prevent damage to the battery due to a lack of active battery cooling. Cars that are delivered to cold regions have battery heaters that are primarily intended to protect the batteries from being destroyed in extreme cold - not to provide an optimal operating temperature.
Volkswagen e-Golf
Prism cells from Panasonic. Volkswagen claims that the batteries do not need an external source for battery cooling and heating. In addition to passive cooling, the e-Golfs have a function that automatically reduces the current when you press the gas too hard for a long time. It official the rationale is to reduce consumption. It real the rationale is likely to reduce the possibility of the battery overheating. Likewise, the charging power is limited if the battery is too hot. This is common on all electric cars, but is rarely a problem on cars with active battery cooling. Volkswagen has given a recommendation that the e-Golf should not be fast-charged more than every other charge.
Conclusion
It is not surprising that premium cars such as the Tesla 3 and Audi e-tron have proper temperature control of the battery cells. Although performance degradation has been demonstrated in the Tesla after repeated accelerations due to the battery cooling not being efficient enough. If it is not the world's best, it is a benchmark for the other electric cars.
I am impressed that even affordable electric cars have active, liquid-based cooling of the batteries. I'm thinking in particular of the new KIA e-Soul and Hyundai Ioniq. Mentions on the fly also the Renault Zoe passenger car with separate air ducts from the air conditioning directly into the battery box.
It's about what we get for our money. If you use an electric car in temperate environments with quiet charging, you can certainly save a few kroner by choosing a model without active battery cooling. The most important thing is that you make conscious choices.
The car manufacturers must then explain how they ensure that the battery cells reach the optimum working temperature. Please mention it in the brochures!
See
Jalopnik have visited Munro & Associates which has screwed three leading electric cars completely apart. Jalopnik characterizes the three cars as "conventional approach", "weirdo approach" and "blank sheet". Guess who is who!
