In my opinion it charges the batteries quite quickly. We recently purchased a new home and thought this would be perfect near the front door. Workmanship? These slippers used to be top of the line, unfortunately no longer! The connectors on the circuit board are marked M+ and M- for proper orientation of the motor wires. We ordered a size 7 and she is 17 months old. Ive only had it a day so time will tell as to the longevity of it but, it seems promising. I thought I was through with wearing any kind of shoe with a heal. That being said, the phone is extremely fast. I believe they will stretch or the inside fleece will flatten over time making them more comfortable. You would think something that costs 70 dollars would work better.