Great that you got it back but any idea why this took so long (getting on for 2 months?)? In theory swapping the battery pack should be quick & easy
for a site with expert staff and the right facilities. Transporting the car to Hyundai UK should only have added a trivial amount of time.
You'd think that... but the amount of admin around the warranty repair was incredible.
Firstly, the dealer took one week trying to troubleshoot the issue. First couple of days they tried charging the car in various ways, then they told me that they opened a technical case with Hyundai and were instructed to carry out various software updates - each time trying to charge the car again. I could see this activity on my app.
It was one week before the dealer told me that Hyundai's tech dept diagnosed the fault as a faulty battery cell, and that the car will need to go to Hyundai UK (I knew from the beginning that it was faulty cell... many posts about it on various EV car forums, not just Hyundai, but I suppose that the techs need to adhere to their standard protocol).
Then, it was another week before the car arrived at Hyundai UK (again, as seen on the app), and another week before the car got disconnected from the app - presumably that's when the techs at Hyunday UK shut down the car's electrical systems in preparation for the 'transplant' .
I don't think that replacing the battery pack on an EV is 'quick & easy' - the removal and refitting of a battery weighing hundreds of kilos from under the car will require special hydraulic equipment, trained staff, and many safety procedures that will need to be followed. Then, there's the draining and refilling of the coolant fluid, electrical connectors, computer adjustment, testing.... I can't imagine that it can be done in less than three days, possibly more if adding a charging cycle and road testing, and will require a minimum of two trained staff (for safety reasons). But this is just my guess.
Either way, the actual labour time is obviously not the reason for the long process. I don't know if working on the car was delayed because they were waiting for spare parts that weren't in stock, or because of issues with availability of the lift bay and/or trained staff.
The other perplexing thing is that according to the paperwork I found in the car, the vehicle was picked up from Hyundai UK on 13th March, and dropped-off at the dealer on 26th March. I have no idea why it took one week for the car to travel from the dealer to Hyundai UK, and nearly two weeks to travel back, especially given that the distance between the two locations is only 50 miles...
Hyundai were definitely dragging their heels with this process, which is odd given that I had a loan car, that presumably they'd want back as soon as possible.
As previously discussed though it's not really the same thing. If a low mileage ICE engine fails then once the failed part/parts have been replaced (often with upgraded ones designed to prevent a recurrence of the issue) it's essentially good as new.
If some cells in a low mileage battery fail then replacing the affected module(s) with new will 'fix' it in the short term, but the hundreds (or thousands) of other cells in there almost certainly came from the same manufacturer and batch and have led an identical life in terms of age, charge/discharge cycles & rates & temperatures, depth of discharge, time left standing unused, etc. So it's quite likely that some of those will start failing too. Which is probably why manufacturers seem to fit new packs while under warranty, and why aftermarket companies in the US typically don't give any warranty on the 'repairs' they do to older EVs.
I don't know much about battery technology, but a quick Google brought up a few companies that offer EV battery repairs here in the UK, see for example
Electric and Hybrid Battery Repairs | Cedar Electric | Worthing , so I guess that there's a market out there.
Having a defined policy is good but does suggest they are expecting some warranty repairs to take 3 months or more??
Maybe it's indeed rare, which is why they are being so generous..
But it can certainly happen - I remember when MB had the Piezo Diesel injectors fiasco, cars were stacked up at the dealerships for months waiting for new injectors to be manufactured (by the Delphi Diesel Systems factory in Blois, France). So probably not common, but it can certainly happen.
In any event, Hyundai's offer is quite generous, given that a 'big' service (spark plugs, filters, ATF, etc) can be expensive. My point was that Hyundai's customer services are better than MB's, at least based on members' posts on this forum.
