RE: Occasional/permanent charger
the opposing opinions are probably both right, depends on what part of the system you're looking at:
- the Fluence is perfectly fine with the reduced charging power from the mobile brick-and-cable, no problem
- the brick-and-cable *should* stand a few thousand hours of operation, but probably doesn't like rain, dirt etc.
- the grid side is potentially subject to wear and tear: So-called "13 amp outlets" can stand occasional short periods of 13A loads (like lawn mowers, hair-dryers, vacuum cleaners etc.) for many years, no problem. But they're definitely NOT fit for constant 13A loads 8hrs a day, 365days a year (which the Fluence requires more or less). They heat up and due to the heat get corroded, and due to increased contact resistance heat up even more - until something melts or burns or whatever. So the mains outlet and wiring need to be real robust and powerful.
My solution: Since 1 year approx, I share a brick-and-cable at work with my colleague (who owns a Fluence too) that's attached semi-permanently to a rain protected industrial type power distribution panel. It's fed by a blue IEC 309 plug (also EN60309, "camping plug" ) from a fully capable 16A outlet of the panel. No irregularities experienced yet.
In your case, I'd suggest you make sure the complete AC path up to the brick is rugged and fully capable (for 16A preferrably) and you check temperature of this path from time to time. Then you should be fine.