Lithium ion cell charge density.

[Chuck Dye]

Shopping for a replacement cell/battery for the cellular phone, I find that the OEM unit is rated 720mAh but various vendors offer 900mAh, even 1150mAh in the, supposedly, same configuration.  On the theory that "if it sounds too good to be true, it probably isn't true," I thought I'd ask the assembled experts:  should I chicken out, buy OEM, or risk $9 on the 1150mAh?

[RocketMan]

Take a close look at their pictures.  I bought an extended life battery for my company cell a few years ago.  It was thicker and I also had to purchase an extended case for the phone to fit the new battery.  I don't remember the mAh comparisons between the two, but the new units lasts for over a week at idle.
The 900mAh battery may just be using improved technology, but the 1150 mAh unit could be an extended life unit that is physically thicker.

[AJ Dual]

A lot of these are just Chinese specifications which translate as, "Let's just make something up."

[RocketMan]

What AJ said is also true, especially if you found the battery on eBay.

[sanglant]

i bought an after market Li-Ion battery pack for my point n shoot, it was cheaper. it is lighter, and it lasts longer in the camera. the Chinese are messing with some freaky tech. but the battery pack works great, does take longer to charge though.

this un. been meaning to pick up a few more.

but do watch the depth in phone batteries the thicker ones are a lot more annoying in the pocket.

[bedlamite]

Batteries can be made lighter and higher capacity at the same time, by making the foil plates thinner, reducing the maximum current it can deliver, and I wouldn't expect it to be as durable. The 900mAh will probably be fine, but I'd skip the 1100mAh.

[AJ Dual]

i bought an after market Li-Ion battery pack for my point n shoot, it was cheaper. it is lighter, and it lasts longer in the camera. the Chinese are messing with some freaky tech. but the battery pack works great, does take longer to charge though.

this un. been meaning to pick up a few more.

but do watch the depth in phone batteries the thicker ones are a lot more annoying in the pocket.

Yep, we have several "Amazon specials" for things like our Kodak Flip Cam-clone. We bought two extra batteries. One died, the other lasts longer than the Kodak labeled OEM. And compared to the price, we came out ahead by 3X the price of one Kodak branded battery.

Shrug. I refer to them as "Stalin Batteries". i.e. "Quantity has a quality all it's own." 

[GigaBuist]

Based on my experience with NiMH batteries I'd say this:

The mAh rating on any battery isn't worth anything if you don't trust the manufacturer.

I've got Energizer AA cells that'll still charge to 2500mAh after a couple of years of abuse.  Like, sticking them in their stupid 10A 15 minute charger type of abuse.  These are usually rated to be 2450-2500mAh.

I get about the same performance out of some Powerizer batteries labeled 2600mAh too.  These cost about 1/3rd that of the Energizers, though, so I'm not miffed that they don't take the charge they're supposed to.

Then I've got some Targus 2700mAh batteries that won't take a charge beyond 2000mAh, if that.  I forget what it was, exactly, but it's far lower than it should be, and these have barely been used at all.

If it was me I'd look for reviews on the product.  If you can find somebody that's a serious battery dork and they say it checks out go with that.  If not, go with OEM.