Super-Drain when under 25% battery?

[Biggest Fro]

Rooted CDMA Hero running FRESH 1.1+Gumbo (0.31)+SetCPU (528/160 OnDemand)

My battery is great, until it hits 25%...

Lasts all day, until late in the night (depending on how much I used it, sometimes it doesn't get that low).

When it hits 25% it starts rapidly dropping, and the lower it gets the faster it drops. Once I hit 15%, I lose nearly 1%/minute.

I don't believe this is caused by a recently installed app, as it has been happening for around a week.

Anyone got any ideas? Is it just a bad battery?

 

[mehbones]

same thing happens to me, same exact setup minus SetCPU

 

[rhunter1]

I noticed the same exact thing today with the same setup. I was shocked I was going to get through 2-full days without recharging and then my battery hit 25% and died within an hour.

 

[Bob Loblaw]

Mine has done this also. Any clue on what causes it would be nice. I've been around 30% only to come back an hour or so later and find the phone dead.

 

[pwrmedia]

What app is everyone using to measure the battery percentage?

My guess is that, regardless of the app, the measurement is not 100% accurate. That would explain why a charge can read "100%" for hours w/ min or no use, and then drastically reduce after a few short app launches or tasks. By the time it reads a 1/4 percentage remaining, I'd imagine it's probably only 1/2 that amount in real time, if not less. I don't see it being a battery issue.

 

[scottmbolt]

What app is everyone using to measure the battery percentage?

My guess is that, regardless of the app, the measurement is not 100% accurate. That would explain why a charge can read "100%" for hours w/ min or no use, and then drastically reduce after a few short app launches or tasks. By the time it reads a 1/4 percentage remaining, I'd imagine it's probably only 1/2 that amount in real time, if not less. I don't see it being a battery issue.

I use Spare Parts to check my battery percentage. I have notice that battery apps tend to actually drain battery more with than without them. HTC Battery Widget seems to be one of the worst.

 

[Biggest Fro]

I'm using BatteryLife from CurveFish

I would guess it has an inaccurate reading, seems to be the most likely idea.

Glad to see I'm not alone, thanks everyone

 

[PGR]

Li-Ion and LiPo batteries have a relatively flat discharge curve, especially at low discharge rates like a cell phone draws. What that means is the battery will hold a pretty constant voltage until they're almost dead and then the voltage will fall off quite quickly.

For example, a LiPo cell has a critical "never exceed" voltage of 4.2V, a nominal voltage of is 3.7V, and they're essentially dead at 3V resting voltage. I'll add that discharging them below 3V quickly does irreversible damage to the cell chemistry so most devices which use LiPo cells have a cutoff voltage of 3V. Li-Ion cells have the same characteristics, but at roughly 0.3V lower voltage across the usable range.

The bottom line is it's real complicated to make an accurate battery gauge for LiPo and Li-Ion batteries. At best they're only measuring a 0.7V difference between fully charged to completely discharged and the voltage drop isn't linear.

I can't find any LiPo discharge curves for consumer electronics type loads. The closest I can find are for bicycle headlights which will draw significantly more current than a cell phone, but the curves should give you an idea of what I'm talking about. And FWIW, my own knowledge about LiPo cells comes from years of using them to power electric R/C planes and helicopters.

Pete

 

[HTCHero203]

I'm using Battery Indicator, It goes to fully charge and if i use it for 1 hour it goes from 100 to 80 and its still good with use like texting, internet, last.fm, built-in music, talking etc. "depends how you use the phone"