[serpix]

You will need batteries with hydrogen fuel cells due to the fact the cells do not throttle quickly based on energy demand. The battery is required as a buffer for quickly discharging larger amounts of energy. So in effect you require a full blown electric drive train but with a smaller battery. In my opinion it is way less complex to just increase the size of the battery and get rid off the hydrogen parts.

[bewilderbeast]

The biggest problem with full electric powertrains is size of batteries and its weight. Keeping the size of batteries small and weighing less is a bonus in ICE car conversions, like I mentioned in my initial comment. Plus better replenishing time, which in most hydrogen fuel cells cars is around 3 minutes.

Edit: the Riversimple Rasa uses a hybrid lithium based battery/supercapacitor pack for this purpose.

[rbf]

With regards to weight - hydrogen tanks are heavy, even if the fuel is light. The tanks on a Toyota Mirai weight 87.5kg (193 lbs). In addition you need the fuel cell, piping, more wiring.. The actual weight advantage is not as great as it might seem.

[rbf]

I see people talking about refuellig time of hydrogen beein an advantage. Although most videoes I see on youtube seem to use ~10ish minutes - and it depends if the pumps has the correct pressure). Recharging an electric car is usually done in a few seconds of active time (plugging in the cable when you park), only if you exhaust the range during one trip you have to wait for recharging.

[magicalhippo]

> Recharging an electric car is usually done in a few seconds of active time

You forgot the 5 minutes spent trying to download and install their own proprietary app, creating an account, just for the app to fail to start the charging...