Excellent! I have 4 that work without supervision for long periods of time without any issues.

I haven't worked with it enough, I have tried it for some time and it doesn't work to charge the AGM batteries. It shows a fault in all cases. If I find the receipt, I believe I can do something with the warranty, otherwise I will only have it for the scooter and I won't buy the same maintainer again

It seems to do its job to some extent. I say this because I wanted a charger-maintainer for a large generator battery (100A). The store that sold it to me told me it works fine. Unfortunately, it doesn't work because in case of a power outage, when the power comes back on, it expects you to select a mode (i.e. what to charge) otherwise it doesn't start. It's not automatic, so it doesn't work. It's purely for a simple manual battery charging.

2 years and something that I have it in an AGM battery (start and stop) with a vehicle that moves once a week, it does its job (the battery almost died the first year, revived it and since then it holds up well (once every 3 months I connect cables to the car and leave it for 24 hours before the cold weather hits exactly.
On the engine that I tried out of curiosity, I didn't have any result as after 10 minutes it turns green (which basically means it has nothing to do) as the engine works every day