Changing a micra k12 battery

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My aunt's micra ain't feeling too good. Jump started it and it turned over. However after leaving it for about 30 minutes idling under its own steam and trying to start it later wouldn't start. I'm guessing the battery has seen better days. Will change the battery soon but I heard it has a radio code? Is this true and what do you use to change the battery without resetting the radio? I don't know the radio code and not willing to pay for it. Planning to get something like this below.

https://www.amazon.co.uk/dp/B008H14SH0/ref=cm_sw_r...

Im a little inexperienced but I gotta start somewhere!

[Nads02]

Might buy the doodah and give it a go. Got a spare battery from my brothers (scrapped) honda jazz.

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Changed it today with the engine running. Battery was disconnected briefly, done all the prep work (removing battery clamp and vaseline on new battery terminals) first so the terminals were only disconnected for 1 minute.

[Nads02]

Super_G said:

OP if she bought the car new it will have the codes in the manual/paperwork. Or even if used and she still has the radio booklet.

Nope just had service history which I found under the passenger seat. Had full service history but I don't think she even knew...

[Nads02]

Super_G said:

OP try 2032 or 0032.
You have 10 attempts before it locks.
If neither of those work you can buy a code online by inputting your serial number. A squid on flee bay.

Thanks for that but I didn't need the radio code. Changed the battery real quick with the engine running. To double check I turned the car on and off once and tuned into LBC, it was playing so I'm assuming the radio is fine