Anyone unfamiliar with battery electric cars (BEVs) may think that all you have to worry about when buying a used (or even a new) car is the price and more mundane characteristics, such as how many seats it has, the preferred body type, and so forth. Should they move forward with their decision to go electric, these folks will learn some lessons the hard way about battery chemistries, charging systems, weight, range, durability, and thermal runaway risks. A relatively recent story from The Autopian adds another layer of complexity to these cars: you should also ask about the thermal management system they use.
Although that is a common way to talk about how a failed compressor can kill the entire AC system, BMW customers adopted the term to discuss a much deeper problem. When the AC compressor fails in some electrified models from the German brand, it affects the battery pack. The reason for that is how BMW decided to save money with the component’s thermal management system.
Most BEVs use an indirect battery pack cooling system, where the cooling channels only interact with the refrigerant circuit to lower the temperature. BMW engineers decided this AC refrigerant loop could take care of everything, so they made it run through the battery pack to save costs. Theoretically, it is a touch of genius. In practice, it was a disaster, with repair bills north of $10,000. Some owners received $20,000 estimates. Several must have sold their affected cars for junkyards (if they were lucky) because it was not worth fixing them.
Tracy disclosed that at least three models are involved with the situation: the i3, the i8, and the 330e. He also wrote that he still loves his i3 and that we do not know how BMW addressed the problem with updates to these vehicles. Those are questions that deserve an answer, so I got in touch with the German carmaker to clarify all of them and a couple more.
According to BMW, apart from the i3 and i8, all plug-in hybrid vehicles (PHEVs) the company sells also adopt the direct cooling system. In other words, the 330e, the 550e, the 750e, and a long etcetera, which should include the Mini PHEVs that share their underpinnings with BMW vehicles. I also asked BMW whether it took any precautions after noticing that an AC compressor failure could cause issues with the battery pack cooling. The German automaker said that the battery software “constantly monitors the status of the system and reduces maximum charging and discharging power accordingly in case of limited cooling.” BMW also said this is the “intended behavior of all EV batteries, independently of the brand.” Fair enough, but that only means the German automaker wants to stress the problem does not damage battery packs.
Photo: BMW
Whether that is true or not, the deal is that BMW’s customers are still receiving hefty estimates to fix the issue. Even if the battery pack is preserved, replacing damaged cooling circuits is quite expensive. The German brand then added that, beyond the software monitoring, its electrified models with a direct cooling system use a filter to avoid refrigerant contamination. However, it did not inform when this filter was adopted. Tracy said several owners tried to adapt a filter in their vehicles, so it is clear it was a remedy rather than something conceived for these models since their original development. Otherwise, they would already have such filters. In the units that do not have a filter, why are the repairs so expensive? I made this question to BMW, but the company is still studying all concrete situations to provide me with the full picture. This is what held this article for some days, but I’ve decided to publish it with what I already have and write another article with the information the company promised to give me as soon as possible.
The German brand reinforced that “the repair bulletins issued by BMW Headquarters describe the necessary procedures after an EV compressor failure with potential contamination of the refrigerant. It is worth noting that, in these cases, replacement of parts within the battery housing is not needed because of the filter.” That led to another crucial doubt. If the issue is with the AC compressor and not with the battery pack itself, how does BMW deal with it? In other words, is a battery pack cooling system defect covered by the eight-year warranty for this component? Or does the German brand consider it an AC defect, hence something that the battery pack warranty does not cover?
Photo: BMW
BMW also promised to clarify that based on former cases as soon as possible, which makes my future article about the situation even more pressing. The German brand also considers that the issue is restricted to US vehicles, but all of the models involved were also sold in Europe and countries on other continents. Although I have only heard about them with American customers so far, people elsewhere may have experienced the same problems. If you are one of them, please get in touch and tell me what happened to you.
More than knowing what BMW has done to correct the situation and which models were affected by it, the main goal of this text is to show how much more complex it is to purchase an electric car than to select one powered by an internal combustion engine (ICE). Although that was predictable, it will certainly surprise those who are used to buying the latter.
In the early days of the automobile, ICE vehicles were anything but predictable. Not even the steering wheel was a given: you could have to use a lever. Each automaker decided how many pedals and controls their cars would have, how the gear selector would be, where it would be located… Nobody had established a standard. In a way, that’s precisely what we are witnessing with BEVs. Some manufacturers even tried to reinvent gear selectors and windshield operation. Thankfully, nobody followed their attempts to reinvent the wheel – and almost everything else they tried to “improve.”
Photo: Nissan
When it comes to how a vehicle is built, BEVs allow for even more variations. Unfortunately for customers, they are all things that must be considered because they were not tried and tested as much as they should by customers. After all, these vehicles are relatively new. The oldest modern production BEV was introduced in 2008, which means it is only 16 years old. The first mass-production model with lithium-ion cells arrived in 2010. Sure, electric cars were some of the first automobiles ever created, but modern ones only reached the market because of environmental regulations and incentives. When you are forced or seduced to sell something you never did, you bake your noodles in an effort to deliver a competitive product and hope for the best. Again, BMW made this move because it thought it was the more sensible one. It just did not count on something so trivial as an AC compressor dying, which it probably should have considered.
That shows that even the guys playing safe by owning a BEV only while its battery pack warranty is valid may face unexpected hurdles. What if BMW considers that, since the compressor was the root cause, the battery pack warranty does not cover that repair? It will be enlightening to learn how BMW handled these cases, but it would also help to hear how things went from the customers involved. As a former BMW PHEV owner, the German brand was always impeccable when dealing with defects in my car. However, it would not surprise me if it said a defect on the AC compressor had nothing to do with the battery pack – even if they are so intimately connected when it relates to the i3, i8, and the PHEVs.
Those brave enough to do what David Tracy is doing with used electric cars should read a lot before making any moves. Does the BEV you want use NMC, NCA, or LFP cells? Does it have fast charging capability? How fast? Has this model faced any serious recalls or problems, particularly anything related to fires? How much depreciation does it experience? Being way more affordable than it was when new can be a massive red flag. Finally, add this crucial question to the list: Is its thermal management system direct or indirect? This question alone may save you a pretty penny down the road.