This battery lasted just a few months past the warranty. Now, it powers my laptop for only a few minutes before shutting off. If I plug my brick in to external power for a second or two, I can squeeze another fifteen or twenty minutes out of it, and if I allow it to "rest" overnight, it shows greater than half charge, so there's clearly just one weak cell out of the entire pack that is bringing down the whole thing. I've read other reviews saying similar things about these bricks, so this is not an isolated failure.
Unfortunately, Sanho won't fix these things out of warranty, or so I've read in multiple reviews. Based on that, I decided to crack this thing open to see what I found inside. What I found was absolutely appalling for a product that costs half a grand.
The first design problem I encountered was that the main circuit board is mounted improperly. It slides into two rails in the metal case, but the rails are entirely too close together for the board's thickness. This makes it incredibly difficult to remove the main board (and the front panel, which is screwed to the board). I was actually concerned that the board might break under the strain; it was that tight.
The second design problem I found is that the circuit board is hard-wired to the battery pack with no connector. This makes it borderline insane to do any repairs because everything is live all the time.
The third design problem, and the one that makes this a terrible purchase, is that the entire battery pack is GLUED to the inside of the case. This means that even though I should be able to buy replacement cells, there's no way to get to the defective cell to replace it. For a product that costs $500, you don't expect the device to be glued together, but this one is.
Of course, the device has many other design flaws, too:
* The supply's power light stays lit even when external power fails, such as when the charger becomes unplugged from the wall. This means that the manufacturer failed to use a protection diode on the brick's input connector. This means that it should be possible to easily cause a fire by shoving metal into the input connector. I have not tried this for obvious reasons, but IMO, that makes this device fundamentally unsafe, and it should be recalled. In hindsight, I'm terrified at the number of times I carried this around in a backpack with various metal objects.... :-)
* The input and output plugs are confusingly similar. In the manufacturer's defense, the connectors have a different pin size, which means that you can't plug the charger into the output and fry things, but there's nothing stopping you from plugging the output cord into the input. It doesn't provide any power when you do, because the smaller pin on the input connector doesn't make contact with the inside of the plug, but you can plug it in. This is problematic if you are trying to plug it in blindly, such as you might do if you are carrying the brick around in a backpack or other bag, and this flaw could have been avoided easily by using a different type of connector for the input.
* The MagSafe cable (I bought this shortly before they stopped including them) failed twice under warranty, and again just weeks later. This illustrates the problem with using cut-offs from dead supplies--many of them likely died because the cables were on the verge of failing.
In short, I'm not impressed with this product, and I would not have bought it had I realized that it was glued together and could not be repaired if a cell failed (which Lithium ion cells are notorious for doing).
My advice to potential customers would be this: Avoid buying high-watt-hour batteries. The odds of a cell failing are about the same whether they're in a single pack or several packs, but if they're spread out over several packs, you've only lost part of your capacity. Better yet, buy a product that isn't held together with glue so that when they fail, they can actually be repaired.