I had the same problem with my original MX-980 battery (purchased April 08). It worked fine for a while, but then started giving out after a couple hours. It was also charging too fast, maybe 20 min from dead to blue light (full charge).
Not sure who the manufacturer was.

I didn't get a free replacement battery. No one had ever had this problem a year ago. Dealer response was "When not in use, the remote should be on the charger". OR "You could try a new battery, but we have to order it". I won't tell you what I paid for an official URC battery. I should have called URC directly, skip the dealer.

Since then it's worked fine. The new battery is a Bexel 1100mAh.

Then my LCD screen was cracked mysteriously, hence the return post.

You can bet I popped the old battery back in before sending it off. Now I'll have an extra.