Battery Bosch or OEM BMW

The battery in my MB was the original Bosch so 20 years old when I replaced it.

(for general reference Lion are one of the worst battery brands out there. Exide are OK but that's far too expensive. Bosch and Varta are generally the exact same product with different stickers on and are always good, and rarely all that expensive.

But during the ownership i found it really reliable, the only things i needed fixing were: battery (it was the original one over 7 years old), tyres and brake discs/pads (consumables on any car) and the regular oil/filter services.

The battery is most likely to outlive the rest of the car. No need to worry. If the car has enough range for your daily need, then keeping it will be the best option.

I will second a class 3 Bosch. I have one in a hilly city that absolutely rocks the steeps and has a great battery life. Going on 2 years strong and I've had zero battery issues. It rains a lot here but no problems with the Shimano drivetrain either, just regular maintenance.

If you really want to buy this one (I find the price quite high, but I don’t know the specific market in Norway), buy an OBD adapter and EVScanner app on iOS with the BMW module. You can check the SOH of the battery and the general state of it as the replacement could be quite costly (around 1500 per module and you could have to replace up to the six if all fail or the BMS). I’d guess the SOH would be at best around 85%, maybe less. The engine itself is pretty reliable as it’s a detuned B48 from the 330i. Go to the infotainment and check the stats from factory and the percentage of eDrive kilometers (full electric) compared to the total kilometers, it would give you an idea of how the car was used and how much charging it got. This specific model of car is great to drive if you can charge everyday and you drive mainly short distances. I do around 80 km daily, almost all highway and my average consumption on those drives is 3.5 liters and 10 kWh/100, so it’s about 2/3 of the cost of my previous car, while beeing a lot better to drive. I’d still buy a 320 or 330i instead because there will be less things that could fail and I would probably not want to get such a high mileage PHEV without knowing how it’s been previously used. Source: I have a 330e from 2021 with 112k km and the SOH of the battery is 90% with around 1400 cycles. Average consumption since factory is 4.9 l/100 km and about half of the distance have been made fully electric.

The only issue we’ve had with it is recently a bunch of warning lights started popping up randomly but all at the same time. I assumed it was a wiring issue or something since none of the systems it said were disabled actually were. Dealership couldnt replicate it so it took a couple weeks of bringing it back and forth every time it happened before they were able to see anything on their end. Replaced the battery and it’s been fine since.

BMW 3 series in the right rear panel. The location is ok, but the box is just enough to slip in a group 49, and there is an air vent hose on the forward side, and a clamp on the rear bottom that is impossible to reach with anything but little elf hands. Then there's also the starter cable, battery management and regular wires running in the same area, all hopelessly in the way..

I went to a Škoda dealer to look at a car to buy. The car was a Rapid 1.4 SE DSG which was advertised at £8995. The car was stored remotely from the dealer, basically in a field. The battery was completely flat.

My new BMW X3 was reliable.

It reliably would NOT start whenever the temperature dropped below -20C, even with a battery tender on it. The dealer couldn’t find anything wrong with it.