Any options to buy more powerfull one? Does the pack ballance trough quick charging? I have elcon but it doesn't charge to full.. Cell ballance seems good anyway after few months using only elcon..
Diginow Super Charger v2 safely charges the battery to 100% and allows a cell balancing to happen. The SCv2 units I've seen to date need the bike keyed on to close the contactor and begin the charging process (after which time you can key off and charging stays "awake" with some auxiliary connector signalling from the SCv2 control computer). Also the SCv2 does not appear to allow passing direct current like the stock onboard charger, which is a rare trick you can use to charge a few percent of one Zero off of the DC system voltage from another Zero, i.e. "bike rescue cable". Thus I would be careful about using the SCv2 for months-long storage maintenance charging instead of the stock onboard charger; I don't think this has been designed for or tested extensively yet.
The wiring connectors needed to make a bolt-in replacement of the stock onboard charger are expensive to source, and its mounting is of a limited physical size, which is why you don't yet see any direct bolt-in aftermarket replacements. Some folks are already prototyping this kind of replacement but at the moment it involves a lot of warranty-voiding labor with rotary grinders and additional clearances.
For an easy no-modification install you could get a Diginow Super Charger v2 one-module (1x3.3kW) or two-module (2x3.3kW) charging system. Mounting a J1772 inlet is easy you don't need to put it in the tank area, you can use some zip-ties (or a fancier metal bracket - I'm prototyping and will do a run of these soon) and there's a few locations depending on your bike and accessories installed to put the inlet. When mounting the charging modules that is very easy to do on S(R) or DS(R), and the FX(S) a bracket can be made above the pillion seat area (or as a small backpack to carry).