It costs $10 for first 10 minutes or $10 per day. The way it works is we pre-authorize $10 on your card, and once the power bank is returned back into the station, we only keep the rental fee based on how long you use the power bank. For example, if you used the power bank for up to 40 min – we charge the fee of $4 and release the remaining amount, if it is more than 40 min you will be charged per day.