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Re: Charging drops to +4mA after 2 hours
What voltage does the battery read when the charger reduces the charging voltage?
Originally Posted by irie27
I have the extended battery, and from "battery low" it can take about 4-5 hours to get to 100% and the green light of happy. But that's on a charging curve that starts with a very rapid increase to about 4v, then a slow decline in charging speed as the charge reaches 4.2v.
Keep in mind that there are two ways of charging a battery - you can charge it up really fast which does a little damage to the battery every time you fast-charge it when it's over 4v, or you can charge it really slowly which preserves the overall capacity of the battery in the long term. Given the cost of these extended batteries, I don't feel the need to cram mine up to 100% as fast as possible.
The way your current ROM seems to be doing things appears to be a good compromise. Fast-charge it while it's still in the "safe zone" (up to about 80%-ish or 4v-ish), then charge it very slowly from there on. That way, if you have consistent access to a charger, you can simply dump power into the battery at a fast clip as needed while never charging the battery up to 100% (increasing the useful lifespan of your battery at the cost of duration of the current charge), and when you need a full charge it will do that with the least possible damage to the battery.
Ideally you really want to keep these batteries between about 20% and about 80%. That's where they are the "happiest" in terms of the battery not losing capacity over the long term. So if you can charge it most of the time to "only" 80%, you won't need a replacement battery as soon.
What the phones should really have is an option when you plug the battery in to choose a charging profile:
- "fast boost charge" the battery to absolutely full capacity (4.2v+) when you know chargers are going to be few and far between and you don't have 5 hours to wait for a normal charge (with a warning that each time you do this you lose a little battery capacity),
- "boost charge" the battery to 4.2v but much more slowly, doing less damage but taking longer to fully charge.
- "preserve charge" would charge the battery to about 4v for the times when you know you don't REALLY need the battery to last as long (you have a charger at your desk or in the car, or you don't need a full day of heavy use). The battery only charges to about 80%, but the battery should last a lot longer.
Instead, most charging profiles do something similar to the "boost charge", and your best bet for battery longevity is to unplug it at about 80%.
ROMs that do a "fast boost charge" are not really doing you a favor unless the cost of a new extended battery is less important to you than the time spent charging it. You're really better off just charging the phone more slowly overnight if you can.