Has any used N900 batteries that are not officially issued? Share some experiences here. Why is the original battery more expensive than others? Just because it is branded with Nokia, or it is really better than others?
Search will answer this for you. Also try Google for stories about cheaper Nokia 5800 batteries (same battery as N900).
They are poorer quality = nowhere near the mAh value reported, also they don't have the info that gets fed back for the discharge status, so the battery is FULL, FULL, FULL, FULL, EMPTY as opposed to the battery symbol showing a steady decrease.
I love cheap fake Nokia batteries and have very good luck with them. I think that if you are careful and get batteries that look like they are authentic, you may get batteries that are actually from the real Nokia production line but from an unauthorized source. I have been buying cheap Nokia batteries for years without substantial problems, except for one that I got that was not quite sized correctly. So I lost a big $2 on that one.
I've had good luck with Japod branded batteries sold by deal extreme. They're not the cheapest but they are much less than nokia batteries. They are around 7 USD at DX. The 3 USD batteries available there are a lot worse.
I bought a "genuine" Nokia BL-5J from dealextreme.com two months ago for 16.77 US and it is indistinguishable in appearance, function, and capacity from the one that came with the N900 so I think that they are telling the truth.
At less than a third of the 54.95 that Nokia USA charges, I am very happy with this purchase and I wouldn't want to save another 10 dollars if it means dealing with the annoyances that others have reported.
With the fake battery I bought (they claimed it was genuine, but it definitely was not), the hologram was different from the original battery. Though it showed the same image, it lacked the depth. It also failed to report the charge levels to the OS so I sent it back for a refund.
This one works really well with my N900. The battery indicator works as usual. I think it's slightly lesser capacity than an original Nokia BL-5J but costs half as much, so I have nothing to complain about.