HELP My Megane's stop-start hasn't worked in months is that a battery thing?

[orwinkeal]

I honestly didn't think much of it at first, figured I'd accidentally turned the feature off somehow. But nope, the light just blinks a few times and gives up every time I come to a red light. Been living with it because the car starts fine otherwise, but a friend told me that modern Renaults will disable the stop-start system on purpose when the battery drops below a certain health threshold, as a way to protect everything else. That kind of makes sense now that I think about it. I was looking into whether a simple recharge would fix it or if the battery is just tired after five years, and I saw that a proper Renault car battery replacement service usually includes coding the new unit so the energy management system resets correctly. Has anyone here had their stop-start come back to life after a swap, or is there a chance something else is dying on me? Would love to avoid a dealership if possible.