Battery Council International (BCI) has created standard dimension for lead acid batteries used in various applications.  U1 battery has a dimension of 7.71 inches length, 5.18 inches width and 6.69 inches height.  

U1 battery is one of the most commonly used batteries in power wheelchair or scooter applications.  For this applications the capacity of the battery can vary depending on the manufacturer and design or the batteries.  There are U1 wheelchair batteries available in 32, 35 and 40Ah sizes.  Â