Is this actually true or a scare story perpetuated by the trade to discourage even the simplest of diy in changing a battery? Car batteries are fairly basic things with a few variations on the same basic chemistry. What exactly is there to program in? And it if is, what manufactures are at it so that I know to avoid them in future.

My Mazda6 has a fairly sophisticated charging system (IELOOP) paired with an EFB battery. I cant find anything on the various Mazda forums I check in on about reprogramming in replacements. Some folk have even swapped them for an AGM replacement apparently without ill effect.

Recently I've had to pull my battery out on a regular basis for recharging due to lack of use at the moment, its a bit of a pain having to go through the relearn procedure for the start stop system every time I do so. I recently bought a memory saver (Draper 22231) to try and mitigate this somewhat, waiting on it arriving still. What is it about these that you don't recommend elekie? Is it down to the potential to hook it up incorrectly, or accidentally shorting out the terminal clamps when it plugged in or something else?

When I've disconnected the battery on my Mazda for recharging, the radio pre-sets and settings have all been present when power is restored again. The things I lose are my saved seat positions, one touch windows positions and trip data (and probably many other things too).

I think as the CMU unit which holds all these bits of data uses non volatile flash memory (its basically a small computer in its own right), so it wouldn't be lost when the power goes off.

Edited by moward on 10/12/2021 at 12:53

Thanks all for the info. Whilst I was very disappointed that a modern battery should fail so dramatically on a 2020 car after just 11 months of daily use, I’m left wondering how to prove if a new battery has actually been fitted. The work was done under warranty so I didn’t get a ‘receipt’ and as the car engine bay is very clean it’s not possible to tell if the battery is new.

Is there any chance that the battery has discharged because of a fault somewhere in the car itself ? Or in other words, will a replacement go the same way ?

Try looking for the manufacturing date on the battery. They can fail in such a short time. A lot of cars require the battery to be "" paired to the car"". There is software in most new cars that can adjust the charge rate of the battery as it gets older. If the car is not told it has a new battery the system can overcharge the battery which is not good for its new life. Maybe your car overcooked its original and hopefully this is now sorted