I have a few chargers including a CTEK but it's the CTEK I use, have been gobsmacked at its ability to revive a battery that would otherwise have been in the bin.
I have an Accumate, a couple, or three, Optimates and several Aldi chargers. In my opinion, there's nothing much to choose between them, but if pushed, I'd go for the latest Aldi version which now comes with crocodile clips, and those battery terminals that can be left attached to the battery, instead of just the crocodile clips as per the previous models. They are made to pass stringent German approval tests, have all the modes (car, bike, cold weather fast charge etc...) and LED readouts for all those modes, plus at £13.99, are unbeatable value for money. The only real problem with the Aldi offerings is that they only appear on sale a couple of times a year, so if you miss 'em, you miss 'em.
IMHO I've never come across a lead acid battery that had suffered deep discharge be restored fully to its original CCA. Always at least 20 to 35% down. This is hard to measure without the right bit of kit. Yes I've brought batteries back from the dead, but I'd never rely on them.
Yeah I gotta say I have no way, or don't know how, to check the resulting CCAs of a battery and also take spares such as batteries in my van so can't usefully comment, am happy to accept you experience All I know is 'beyond the grave' batteries have been returned to life started and run my SBKs for the limited usage they get - and that's all I can say.
When I have needed them, in the early days I used optimates but moved over to Ctek and not had a problem. https://smartercharger.com/
