[Samsung Galaxy Nexus] ttabbal:
I will keep updating this Google spreadsheet as we go. I'm the only one that can edit it for now, but I'm willing to add contributions from others, just email me. If you wish to do a few of them, I'll give you edit rights. I'd make it fully public, but every time I've seen someone try that, they spend more time reverting vandalism from random children on the net than updating it.

http://goo.gl/ws87w

There's only one battery in there right now, the Hyperion 3500, but I'll be adding more as I get them. I'll also be testing the stock GSM 1750. I'm re-testing the Hyperion now and I will keep the doc updated with the latest/averages. The next battery purchase I make will likely be the Samsung 2000 mAH, just to compare.

Testing method:

I'm using an R/C battery charger/discharger for the testing. It measures true battery capacity on charge and discharge. For discharge, I set the voltage cutoff to 2.9V (2900mv) which is the safe zero point for a single-cell lipo. I'll report averages when multiple tests are performed. I will also be evaluating the effect of various discharge rates, currently I'm testing at 1A discharge. For extended batteries, 1A is well below .5C, this is well within range. The next Hyperion test will be at .5A just to see if it makes a difference.

What will NOT be reported on this spreadsheet is anecdotal evidence like "ran my phone for 12 hours with screen on for 2.5". I am interested in real data across a known load. There are plenty of stories on here now, there's no point in restating them.

What about <random ebay battery>???:

You have a couple options. You can send me one for testing, which I will return to you at your option (I'll pay for return shipping), or you can set up a tester of your own and report data to be included in the list. I don't have unlimited money to spend testing batteries. That's also why I won't be testing Mugen/Sedio batteries unless someone sends me one. They cost too much. Though if someone has the offer for a $20 NFC upgrade from Sedio, I will cover that cost if you send me the non-NFC battery for testing.

I think your method sucks:

Well, that's your right. If you think you have a better one, post. I'm willing to listen. Know this though, I've tested this setup against known batteries and get consistent results. If you don't have data to back up your claims, I probably won't change my mind.

What about "reserve capacity" (below 2.9V):

Discharging below 2.9V will damage the battery cells. I have no interest in doing that. Cell phone batteries include a protection circuit that would likely prevent discharge much below this level anyway. If a user can't actually USE the capacity, it's irrelevant to the user. If I have to destroy the battery cell to get at the capacity, it's not really there. Unless what you are selling is a single use battery?

Why should I care? It's still a good deal:

Perhaps you don't. But consider this, if they lied about capacity, what else might they lie about? Perhaps they used the cheapest cells they could find, so you only get tens of cycles instead of hundreds. Perhaps there are other problems. Perhaps not. I also take issue with made-up numbers being used to sell products. It's no different than advertising 1 gallon of milk, then only giving the customer 75% of that. It's not acceptable with other products, why should it be acceptable for batteries? The OEM cells test out fine, I see no reason aftermarket batteries should be held to a lower standard. Particularly for those that cost significantly more than OEM batteries.

License: Anyone is welcome to repost the data anywhere. I do ask that you link to this post though, just so that any other data reports can be added.