I've been using the fan a little over two weeks and have found it very helpful keeping our dog cool in her K&J custom crate on hot days when traveling. It's fast & easy to mount or dismount, and on high speed has some serious fan power. I actually haven't yet timed how long the fan will stay on until it needs charging, but it lasts quite a while on full speed and works perfectly for my needs. However, my crate is mounted in my truck bed and is exposed to direct sun, so I only put her in her crate with the fan on while doing detection work, training or short drives lasting 30 to 60 mins. I also use a wireless thermometer to monitor the internal temperature of her crate so I can constantly check my phone to ensure it's not to hot for her.
All in all, the fan 2.0 is a great product and highly recommend it 👍