I have tried 3 different replacement batteries for my Dell Vostro 1520.
The message is the same - it does not recognize the battery and cannot charge it.
I have plugged and unplugged, updated my bios... When the battery arrived it did recognize it
while it had the orginal charge, but then stopped once it ran out. I can no longer us it.
This is a geniune Dell replacement battery and all numbers on the back match the original battery.