The CTEK 5 is, according to its blurb (
https://smartercharger.com/?s=reconditi ... de&x=0&y=0)
far more advanced than the Halfords standard £9.99 trickle charger we're all used to.
They claim smoothed out (much reduced) 100Hz ripple on its 12V supply meaning far safer to connect in car without first having to disconnect battery from the car as should be done on today's digitally controlled car sensitive electronics if using an olde-style charger.
And that they have an advanced monitoring process (including ambient temperature control) that will ensure greater than 80% of your battery's
available capacity being re-charged.
But, having said all that, once a battery's life is reduced -- and that life starts reducing once the electrolyte is added (10:1 sulphuric acid) -- then no amount of care and monitored charge rates will give back life that's gone past. CTEK are using the word "recondition" in a manner that implies that life can be given back to a Pb-acid accumulator by their product. It can't
