Battery OEM Mazda or OEM BMW

2014 Mazda 3 with 322,000 kms, it's doing fine. I'm still on original engine, transmission and starter. I use it almost daily in traffic. The only problem is that the battery is slightly more costly than a standard one, which offsets the miniscule fuel savings you're getting from the system

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 have this car. Most important is that below -12C, the gas engine stays on, and won't let you drive around on electric alone. That accounts for several months of driving in our winters. Secondly, even in temps below +10C, you have less access to the battery's energy, so your range drops even independently from the usual cold temp range losses.

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..

My brother and I both have/had 6 speed 2015 Mazda3 (me the hatchback, him the sedan), and both of us had terrible issues with the Mazda brand batteries.

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.

The battery lasted about two years. I had a company car at the time and only drove the BMW on my days off, and didn't drive long or far. The short, infrequent drives basically never allowed the battery to completely charge, resulting in it's early death.

Dealer measured my 2021 m340xi battery at 700cca last week under load test (vs 850 cca capacity) and said battery needed to be replaced. Terminal was stamped 26th week of 2020.