I bought this booster pack to replace my old lead acid booster pack. I used it today to boost my car which had been sitting for two months. The voltage was less than 3 volts so I had to use the override button. After a few seconds the volt meter showed 12+ volts and I was able to start the car with no problem!
After I went to charge the pack and the error warning light was blinking. In the manual it says a blinking error light means the internal temperature is too high and to wait for it to cool down. So I left the pack for a half hour and tried again, and it started charging no problem.
Also I bought the AC charge adapter for the booster pack and I highly recommend it. After around a half hour plugged in it was back to a full charge.