The 20% to 0% is certainly nothing new. That's the true usable capacity. Li-on batteries need protection from running down. All desires shut down at around 15% or so.

However, the problem is that that 15% should register as 0%.

If you see it shut down at 15-20%, if you boot it up immediately (may need a little power to do so) it will read at 0% - which is what it should have read as.

So the fact that it shows fully charged at 80%, although I've never witnessed this - actually comes as no surprise to me. That 80% is actually the true usable capacity of the battery. The battery stops charging when it hits the battery's capacity in millivolts.

In short, you are not losing anything. You are using the full 100% usable capacity of your battery, however only around 80-85% of the battery is usable. Your software is seeing the entire battery as 100% where it should only see the 80-85% as 100%.

I hope that at least helps some way towards understanding.

Now is it possible to truly calibrate the battery to show 15-20% left as 0%? Yes, however this requires a very specific kernel which requires being rooted. There may be other ways, but I've not tried any.

 

ive also got this problem with my wifes desire, altho slightly worse, it dies at around 35%. as you say, when its switched back on it shows 0%.

my wifes desire IS rooted tho, so could you let me know how i can at least get it to show the correct %age please? which kernel do i need? at present shes got manu1.4 or something i think.

one other thing, it dies mid-afternoon on light usage, so is it about dead anyway? its only around 20 months old :-/

thanks

 

Manu 1.4
Nexus one battery calibrator app
This link http://forum.oxygen.im/viewtopic.php?id=723

 

thanks, already got that kernel, so running the app now. bit confusing, thought i was doing it wrong having to keep putting those different values in, and also a bit unsure about how ill know when its charged, as it says to LYPTFA, which means screen will obviously be off, so cant see when the CHGTF flags lit.

but...... ill just follow instructions and see how it goes. possibly leave it charging all night.

thanks

 

ok, not too sure whether thats gone ok or made things worse to be honest.
it was all a bit strange really, but made me hopeful that it was improving matters, as, during the calibration, it would reach 15%, then down to 10%, then shoot up to 18%. it did this a couple of times, so i was hopeful i was 'discovering' new juice that was being ignored in the past. all the time i was watching the voltage didnt reach 3201 and it did indeed seem to be going down slowly.

one hiccup was that on about 10% i left it for a few mins (voltage didnt show any signs of reaching that figure yet) but when i came back the phone was dead!! grrrr..... i was so annoyed id missed the 'plug it in NOW' message.

had no alternative but to start charging again and hope for the best. and again, something happened to give me hope. firstly, i switched it straight back on, it showed 0% and died. i charged it for about 10 mins, then unplugged. it showed 30%, then as i was repeating the early steps, it was taking its time dying, so again i thought i was discovering new juice that would be mine all mine when it was recalibrated

all went ok this time, plugged it in when it said and left for 5hrs to charge in airplane mode. switched off and rebooted this morning, phone started at 100%.

however, after 10 mins on facebook, phone was showing 94% :-( half hour later it was 90%. its not looking good. battery may be dead by dinner :-/

anyone know this software and whether theres anything else i can try?

thanks

 

Well OK, youi have to keep the screen awake and the phone in your hand whilst its deing. This can take 5 minutes or so. When it says plug it in, plug it in. Your radio at this point is still off (leave it off) and let it charge. Thats all.

Yes it does appear to shoot to 30% when learn mode is enabled.. Mine does that too.

I would say calibrate again.

10mins facebook, 6%. Yep thats about right. Although if you're hoping for us to spot anomolies, we cant without knowing screen brightness, screen on time, and screen % from the battery info screen.

 

ok ill do that. just one thing that i dont understand about your answer. you said i have to keep screen awake and phone in my hand for 5 mins whilst its dying. thats sort of what i was expecting to have to do. i thought the software would drain the battery quickly whilst i waited. however, it was a couple of hours or so. and probably took longer because i was in airplane mode.
have i missed something out?

thanks

 

maybe your battery is so far off the true value that it shuts down far too early. Watch the mV section and match it to where it should die as according to the guide.

 

do you mean the 3201 figure? it should hit that then die? what if it doesnt? it would still just calibrate it anyway wouldnt it and nothing i could do to change it?

thanks

 

It will. That is when the battery cuts off, regardless of what the software tells it.