End of the scare of expensive traction battery replacements. That’s probably what Volkswagen thought when it came up with the idea of organizing a training session for a group of motoring journalists, which it usually gives only to technicians from authorized service centers. In it, he tried to show that defects in the battery of an electric car do not necessarily ruin its owner.
“Almost everything you see here can be repaired,” says trainer Roman Pošva at the beginning of the workshop. He and his partner Radek Nekněz give repair lessons to mechanics, without whom, really only with a slight exaggeration, they are not even allowed to approach electric cars. So-called EPOs, electrically educated persons, usually leave their courses. More diligent listeners can take it to VNT, or high-voltage technician.
But only high-voltage experts, VNE for short, can even repair traction batteries. “They are the smartest people with electrical engineering education,” assures Mr. Pošva. Which, just by the way, shows that the old stereotypes about the car service environment, fueled by frequent reruns of the movie Jáchym, throw it into the machine!, are no longer completely valid.
At the same time, a layman might think that something like this can be learned in a weekend. The repair itself is similar to when the pencil flashlights in a children’s toy reach their end of life. With the difference that not all eight change at once, but usually only one.
It is also different in that instead of pencil batteries there are so-called modules in the car. The current MEB corporate platform uses eight to twelve of them in batteries, depending on the capacity of the battery. And only the guts of these modules form the battery cells.
“If the battery cell is defective, the entire module is always changed,” explains Roman Pošva. According to him, the very design of the module precludes further repairs. “When you try to take it apart, something always gets damaged,” he adds.
Owners of electric cars do expect that their battery will lose capacity over the years, but they often don’t even think that they could end up standing on the road due to a sudden malfunction. At the same time, a seemingly banal stimulus is sufficient: for example, when the cell stops supplying information about the temperature to the control unit. Or when the voltage difference in the cell reaches 200 millivolts.
Handling with gloves
While up until now, car mechanics could only worry about getting their hands dirty from oil, current electric cars are dangerous machines for them. There is definitely a difference if they are tickled by the voltage from a 12 volt battery or hit by the 400 volts that an electric car drive works with.
Any handling of the battery therefore begins by disconnecting the entire car system from high voltage. For this, a special maintenance connector is used, which the technician secures with a padlock when it is switched off. So that someone doesn’t accidentally turn it on again.
Then there is the voltage measurement via the control units, each step is recorded in the protocol. Records of what, when and who did to the electric car are an integral part of every repair. It’s all about life.
Just removing the battery from the car chassis takes about an hour. Despite the weight of up to half a ton, it is not a physically demanding task thanks to the mechanization. “You might be interested in the fact that you must not sit in a car with the battery removed,” points out Roman Pošva, saying that it is a structural element of the car.
Before the specialists begin the repair, the battery must be acclimatized to the temperature of the surrounding environment. And also perform a pressure test, which will reveal any leaks. “Repairs are always carried out in pairs. One technician is in charge of the work and determines what and how to do with the battery at any given moment,” explains Pošva.
However, technicians do not need to remember the work procedure, there is a manual issued by the car manufacturer for everything. It’s a bit like a furniture assembly guide, only a bit more detailed.
So removing the faulty module and replacing it with a new one doesn’t seem complicated, but as the trainer points out, many things can go wrong. For example, disconnecting the module from the rest of the battery has its own precise procedure, the violation of which at best results in the burning of several relays and fuses.
Special high-voltage overalls and a protective shield made of darkened Plexiglas to protect the pupils from possible electric shocks prove that it is not all fun. Both men wear it every time they even come close to the exposed battery. And although handling the module requires feeling in the hands, solid leather gloves certainly do not help.
But in reality it is even worse. Underneath the leather gloves are another pair of rubber gloves. This is to prevent the leather glove from becoming conductive due to a sweaty hand.
During work, expert Radek Nekněz often remeasures whether the voltage has reached places where there should be none. And as soon as he disconnects a wire, he immediately covers the exposed terminal with a plastic cover.
A workshop crane called a giraffe is used to remove the module from storage. Although the module has the dimensions of a smaller safety deposit box stored in a bank, it weighs about 30 kilograms. As soon as the giraffe delivers the module to the workshop, Roman Pošva picks up a marker and immediately marks it. There is a ready-made new module next to it, and both look absolutely identical: “You can’t tell the difference between them, they are both clean. Even the date of manufacture may not always be a clue,” the technician points out.
And then the high-voltage expert becomes a handyman for a while. Together with a colleague, he fills a special dispenser with heat-conducting paste, in which the new module will be seated, and applies the mixture to the prepared template. When storing a new module, it is a matter of millimeters: once its cover is attached to the paste, it cannot be moved in any way.
Fifteen centers, one hundred cases
There are currently fifteen places in the Czech Republic where they can deal with electric Volkswagen batteries. And during their existence, they already have a hundred solved cases. “In many cases, it’s about checking the condition after an accident. But the massive case can reliably protect the inside of the battery in most cases,” says Roman Pošva. At the same time, he points out that the Czech Republic was one of the first countries where the high-voltage accumulators of Volkswagens began to be repaired. “We have overtaken even countries such as Austria or Denmark,” adds the expert.
The complete traction battery is by far the most expensive part of any electric car, accounting for a third to a half of its price according to various calculations. Automakers themselves do not like to talk about its price, so as not to scare potential customers unnecessarily. But also because its complete replacement due to a defect is rarely in reality.
It could be compared to an internal combustion engine, which is also not normally replaced entirely in a car. And if so, it is usually due to a manufacturing defect, which usually becomes apparent already during the warranty period.
It is precisely the warranty on the traction battery that tends to be remarkably long for automobiles, for the Volkswagen concern it is eight years or 160,000 kilometers driven. And so cases where someone would pay for a battery repair out of their own pocket have not yet been recorded.
When that happens one day, it will probably not be hundreds, but rather tens of thousands of crowns. The price of one battery module of the MEB platform is around fifty thousand, to which must be added the work of two specialists for the duration of one work shift.
For such money, particulate filters are changed for some car brands, automatic transmission repairs tend to be even more expensive. Almost every car has an Achilles heel. Only time will tell if it will be the electric car’s traction battery.
