We have a Torqeedo which I think is a similar battery and charge from our solar panels, 2 x 100 watt. Connection is via an old 12 volt supply laptop charger which raises the output voltage to I think 17 volts. It works well raising the charge level by about 10% an hour.Can anyone offer any advice on the best approaches to charging an electric outboard - ePropulsion - solar? Dedicated solar panel? 12v battery? Inverter?
That's exactly what I do, never had a pub turn me down yet when asked if I can charge my Epropulsion. Failing that then use the inverter when engine is on.The ePropulsion's battery is really quite big: 1.2kWhr (at 48V I think) which equates to around 100Ahr from a 12V battery. So charging it from the boat's batteries without any additional, external, source of power such as shore-power, engine or substantial solar will put quite a dent in the boat's batteries state of charge whatever combination of inverters or chargers you use.
Thus go for whatever is convenient rather than attempt to optimise efficiency which will only make couple of percent difference.
FWIW, I think a mains charger is the best option as it can be taken with you and often you can plug-in at your destination ( eg a bar but surely you never go to these ). And, since you already have the mains charger, just use it with the inverter when aboard; a tad less efficient maybe, but it avoids carrying extra stuff. Use of such things as old laptop chargers of unknown efficiency or safety seems a complication too many to me!