Our DC59 stick was lasting 1-2minutes. This battery replacement solved that and restored it to functioning as-new. The changeover is relatively simple, but not immediately intuitive, but there is a Youtube video that shows how to remove the old battery and replace it. Once the few "tricks" are revealed, it merely involves removing two phillips head-screws and replacing them. Highly recommended if your vacuum is waning. Simple DIY fix.
The battery looks almost identical to the Original Dyson one, and seems to perform as expected.