Battery Replacement On A Dell Vostro?

I replaced a Dell battery with a non-Dell one in a Vostro 1720, under Windows 7. The battery powered the laptop until the manufacturer's charge (as recommended) discharged. It recharged to 10% but no further (perhaps I imagined this and it just did not discharge fully). At boot-up, the message 'Windows cannot identify the battery' comes up. This is the same message that came up when the old dead (and broken) battery was in place. I cannot find any way of managing the battery by software (this is probably a Windows 7 problem - it was possible under Vista, I think). I think that Windows 7 is just refusing to 'identify' the battery. I've tried all the permutations of mains-power/battery connection/disconnection.