I have been thinking about adding range extender generator option to my Q210 for some time now and would like to exchange ideas with you to explore possibilities. Initial calculations say that with just 3.0kW generator my Zoe could travel around 300km @70km/h and around 230km @80km/h with gasoline consumption around 2.5-3 litre / 100km. Of course, all those are all just theories and will have to be (dis)proven in real life testing. 
First, connection to the battery bus - best place and most logical candidate I found is battery disconnect "switch" under the floor on the front right side in the cabin. It has to be modified with external wires and connected via fuse to Anderson (or similar) connector where generator will connect.
Second is the power source - there are multiple possibilities (e.g. expensive DC power sources with additional conversion losses from regular 230V AC generator), but the simplest and cheapest one I found is 3-phase power generator with full bridge rectifier to produce needed DC voltage. Standard 380V AC generator is producing around 540V DC, so it has to be rewound to 28% lower voltage to get 390V DC. Of course, there's also a question of the generator location - it can be on the trailer (pitty that option is illegal since Zoe doesn't specify tow weight on the homologation), it can be in the boot (needs good air flow for cooling, getting out exhaust pipe, sound proofing, loss of space in trunk...) or it can be on the roof racks (possible if the generator weighs less than 70kg, needs to be enclosed in the waterproof box).
So far, so good - but that is leaving us with third part of the puzzle...
The car itself - how will the electronics in Zoe react to fact that you are adding power source between the battery and inverter? In the best case car will see that now it is using less power (e.g. 4kW from the battery instead of 7kW assuming generator is providing 3kW) and enable driving longer distances. In the worst case, car will see that current in the battery (if there's such measurement) is much less than current in the inverter and it will raise error and refuse to drive on.
So, my question is if someone has already tried something similar?
And of course - all comments and ideas are welcome!
Kresimir
First, connection to the battery bus - best place and most logical candidate I found is battery disconnect "switch" under the floor on the front right side in the cabin. It has to be modified with external wires and connected via fuse to Anderson (or similar) connector where generator will connect.
Second is the power source - there are multiple possibilities (e.g. expensive DC power sources with additional conversion losses from regular 230V AC generator), but the simplest and cheapest one I found is 3-phase power generator with full bridge rectifier to produce needed DC voltage. Standard 380V AC generator is producing around 540V DC, so it has to be rewound to 28% lower voltage to get 390V DC. Of course, there's also a question of the generator location - it can be on the trailer (pitty that option is illegal since Zoe doesn't specify tow weight on the homologation), it can be in the boot (needs good air flow for cooling, getting out exhaust pipe, sound proofing, loss of space in trunk...) or it can be on the roof racks (possible if the generator weighs less than 70kg, needs to be enclosed in the waterproof box).
So far, so good - but that is leaving us with third part of the puzzle...
The car itself - how will the electronics in Zoe react to fact that you are adding power source between the battery and inverter? In the best case car will see that now it is using less power (e.g. 4kW from the battery instead of 7kW assuming generator is providing 3kW) and enable driving longer distances. In the worst case, car will see that current in the battery (if there's such measurement) is much less than current in the inverter and it will raise error and refuse to drive on.
So, my question is if someone has already tried something similar?
And of course - all comments and ideas are welcome!
Kresimir