We do not normally talk about "Wattage" but AMnps out.. The Magnetik is not nmuch of a chargerm no regulaton to speek of (Well Ferroresonant) known as a battery killer.
They make both "intergrated" units (Onverter is also power distribution) and "Stand Alone"
IF you want to replace JUST the converter
Progressive Dynamnics 44600 for intergrated 9200 for Stand Alone and go with the 45 amnp model
The slight upgrade will likely work well, but going too big on the converter you need to upgrade the wiring as well between converter and battery.
ALSO the converter should not be nmore than 1/3 the battery's C/20 rating A single Group 24 needs about 20 anps max charge and they sinmply do not come that small so if you have a single Group 24, consider a battery upgrade
Like a pair of GC-2 in series.. They will last a long timne with a 45 amp converter Or a 60,, not so long with an 80 but you may not notice the difference.