[Droid Incredible Android Development] byrong:
ms79723,

I'm not a coder, so I can't comment on what the kernel is actually doing, but if it does what you claim, it is problematic at best. Your statements show a lack of understanding of how lithium ion batteries work, which is worrisome given that you are tweaking how it is charged.

First off, you list trickle charging as a "feature" in the original post. Trickle charging should be considered a liability with our battery chemistry, not a feature:

"No trickle charge is applied because lithium-ion is unable to absorb overcharge. A continuous trickle charge above 4.05V/cell would causes plating of metallic lithium that could lead to instabilities and compromise safety." [Source]

Nonsense. It doesn't matter if the phone is consuming power: if the current that it is receiving from the charger is greater than the current being consumed, the battery charge keeps increasing.

Your argument is akin to saying, "I can never fill this bucket with this hose, because the bucket has a tiny leak in the side." Not only can you fill the bucket, you can make it overflow.

It's not as if the phone consumes more power at 95% than it does at 50%. That has nothing to do with the 0-90 / 90-100 difference, and that difference exists even when charging devices that are off. You can refer to my same source above: the charge current is decreasing as the cell approaches its voltage limit. Whether the device is on or off is irrelevant.

If the charger itself could power the phone, the battery depletion while on the charger would be so insignificant that you would never notice it. No trickle charge would be needed, and no topping charge would be needed. Batteries have a self-discharge rate, but would only be noticed over weeks.

Unlike many other electronic goods in our life, the Incredible cannot run directly off of AC. It is always running off of its battery. You can test this in two ways:

1. Plug the phone in and pull the battery (it will turn off)

2. Try to power the phone on while it is plugged in, but has no battery in it (it will not turn on)

How can you control the current so precisely that you end up with a net of only +2mA? Even relatively idle devices will have fluctuating power needs. Given the vast number of applications that any given user could have installed on his or her phone, how do you scale current rapidly enough to maintain the delicate balance that you describe?

Well said.

Thanks for that link: I hadn't read that specific piece before.

Good question. Maybe none, but I agree that further disclaimers should be put into the original post.

With custom themes, ROMS, etc, the worst that people can do is brick their phone. When we start hacking charging methods though, the stakes have just gone up exponentially. We're no longer just talking about the risk of a bricked device, we're talking about the risk of fire, explosion, and injury.

Am I saying that this kernel will light people's phones on fire? No, I seriously doubt that it will. I trust that the engineers of this device (and our batteries) have put in enough safeguards to otherwise prevent explosion. With that said, however, this sounds like it will still accelerate wear and damage the battery.

Again, I can only speak to the claims that are being made about this kernel. I have not tested it or looked into the code. But the claims themselves are worrisome. I don't doubt that the described methods can increase available battery in the short-term, but it remains to be seen how much damage it is causing in the long (or medium) term. And given the drastically different performance that users are reporting, it seems like a risky bet.