Adri

I don't understand all the fuss about VOV and VOO.  
In 20 years I sold over 300 x '6500' gens (for petrol or LPG), so called because they're all practically the same, including Honda, made in China.
A decent sparkie will install a change-over switch and socket for the gen and it will work perfectly up to 4kW load (at 50Hz ... the 6500Va rating is for 60Hz) and will sign a CoC on completion of the job.  If it's rated 230Vac output there's no need to modify the alternator or use a transformer. Finish.
(It's the usual story : "Bnllsh1t baffles brains"....)
 

Someone might be interested in my monitoring of my batteries : to show true batt. volts and charge/discharge current.
I use a Mooshimeter I bought on the 'net.  It can display 2 functions simultaneously : my case batt. volts and true charge/discharge current.  I connected 3 input plugs to (a) B+ terminal of Axpert, (b) B- terminal on Axpert and (c)  B-  terminal at the batteries, so creating a small volt-drop. It's then displayed in the 100mV range which is exactly proportional to the current [in both directions].  By quick calibration I measure about 5mV/A.
It's that simple and I carry my phone/display anywhere in the house.  It has logging functions I haven't mastered yet!
If someone needs help/more info, let me know.
 

I once converted a mains-type lead light (the workshop type, for working under cars) with a standard headlight bulb where the low-beam filament had burned out, with croc clips.
Turned out to be the best 'rough' load for many 12V (and less) applications, like testing batteries and chargers. Particularly because of the steel wire lamp protection cage-design.

I don't understand all the fuss about VOV and VOO.  
In 20 years I sold over 300 x '6500' gens (for petrol or LPG), so called because they're all practically the same, including Honda, made in China.
A decent sparkie will install a change-over switch and socket for the gen and it will work perfectly up to 4kW load (at 50Hz ... the 6500Va rating is for 60Hz) and will sign a CoC on completion of the job.  If it's rated 230Vac output there's no need to modify the alternator or use a transformer. Finish.
(It's the usual story : "Bnllsh1t baffles brains"....)
 

Google for suppliers, e.g. SparkFun.
 

Someone might be interested in my monitoring of my batteries : to show true batt. volts and charge/discharge current.
I use a Mooshimeter I bought on the 'net.  It can display 2 functions simultaneously : my case batt. volts and true charge/discharge current.  I connected 3 input plugs to (a) B+ terminal of Axpert, (b) B- terminal on Axpert and (c)  B-  terminal at the batteries, so creating a small volt-drop. It's then displayed in the 100mV range which is exactly proportional to the current [in both directions].  By quick calibration I measure about 5mV/A.
It's that simple and I carry my phone/display anywhere in the house.  It has logging functions I haven't mastered yet!
If someone needs help/more info, let me know.
 

I was unclear about warranty : the unit was originally bought by another business but remained new and unused until I bought it October 2018.
I would  like to make contact with folk who do such repairs. I am electronics technician (for 40 years) with some experience in PV  but still could not find the fault in the unit. (No load connected.)
And thanks for the suggestions so far!