18 months after getting my GH7, the non-maintenance free battery that came with the car gave up the ghost. A friend came along, jump-started it, and we made it to a shop nearby and changed it out for a Bosch S3 battery.
Another 1.5 years down the road, the battery was showing signs of needing to be replaced. I drove to the same shop and this time round they sold me a Bosch S5.
I don’t really know what the difference is, but I guess the proof of the pudding is in how long it’ll last. Fingers crossed.