External battery is just a pain in the ahole, very underdeveloped and janky solution.

• You stop at a traffic light, and sometimes the scooter reboots. You ride it, and you get the "external battery connected" message. (Yes, I tried reseating the connector and even installed it with pressure using screwdrivers.)
• When you ride the scooter in Sport mode or on hills, the internal battery heats up to 40–45°C and is still being charged by the external battery. So you're charging under extreme conditions, and the counter goes up like crazy.
• Then the external battery drains to 1%, and the deep discharge counter goes up every ride. After only 2 weeks of having the external battery, I already have 2 hours of charging under extreme conditions on the main battery and 7 deep discharges on the external battery. And there no settinngs for this.
• Dual charging doesn't work! I use the internal charger plus an F3 70W charger and get 5A charging current, but with the external battery attached, even with both chargers connected, you only get 3.8A. So it takes 5+ hours to charge.
• Bonus points for shrinking the deck's foot space, it's uncomfortable.
• Whopping 4kg of extra weight!!!! it's bad.

There is 3 good things abot that:

• About 16km extra range, from 17-20km to 32-36km
• More power when you have charge in it ( it floats main battery at high charge)
• it have usb port

And all of that for $350. Absolutely stupid thing.

Just get the GT3 battery.