The first one they sent me worked for about a month. I inflated 1 tire per charge. Then I got the code "Err" and it stopped working. I contacted customer service and they responded quickly and sent me a replacement within 5 days! I was impressed. But the new battery didn't work no matter how much I charged it. And yes, it was charged. I used an old battery and it works! Albeit a bit temperamental. I need to make sure the battery is installed securely or it won't work. I still only get 1 tire fill per battery charge.