How can I tell which of my batteries is in the best health

[Chairman]

I have 3 bosch 625 batteries. All of different ages and had a variety of treatment. The all charge to 100% but how do I actually test to see which one is the best? Thanks in advance for any help. Even if there is only a few % difference between each of them I would still like to know the various differences between each of them if possible

 

[Beaker2135]

A Bosch dealer can do a discharge test, it use one full cycle from the battery life though
I had one done on a used battery I bought, it was 90% so in my case originally a 500 as bought used 450. That was fine for a spare and good to know, although I’ve never had my original tested
There will be a fee for the service so maybe someone will have a way to test it yourself

 

[cozzy]

Fit each and do an identical ride, see how many miles they do.
My new spesh 700 was pretty much identical to my original 2020 battery, which surprised me.
Unless my new battery is rubbish haha.