Actual capacity of your battery

sibere

Retired Recognized Developer
May 14, 2006
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Paris
After more than a year of usage, I started to feel that the battery was getting old. BMW pro was reporting an estimated capacity of 2000mah. So I decided to buy recently an ANKER 2700mah and I really felt the difference!! BMW pro is reporting a capacity of 2800mah now which is close enough to the real capacity of the Anker. That's almost 40% more juice to power my (not so) little precious :)
 

Formhault

Senior Member
Jun 10, 2011
11,517
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Bucharest
After more than a year of usage, I started to feel that the battery was getting old. BMW pro was reporting an estimated capacity of 2000mah. So I decided to buy recently an ANKER 2700mah and I really felt the difference!! BMW pro is reporting a capacity of 2800mah now which is close enough to the real capacity of the Anker. That's almost 40% more juice to power my (not so) little precious :)
Make sure that you are using a TW-based ROM... BMW's estimations seem to be wrong with a, say, CM-based ROM. I get 2300 - 3850 mAh estimates (on CM10.1), lol.
 

A-mak

Member
Sep 16, 2011
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I have 3 batteries, 2 aftermarket, 1 original. I'm a bit slack with letting the program know when I've changed but:

Android Tuner Pro
Average use: 2587mAh

The two aftermarkets are rated for 2600 which are the ones I mainly use. They were generic ones that came with a external charger.
 

g3k

Senior Member
Jul 17, 2006
128
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0
Istanbul
Yes it's accurate if you respect the conditions

Hello,
Being a long time user of Battery Widget Monitor, i wanted to try that Nova tester, though at first sight, i've thought it would be another useless "battery info collector" to show nothing more than Android but in a fashion way.

No. In fact, this tool can succeed to reveal reliable results. I can confirm that. But the user should pay attention to assure stable testing conditions.

If you assure the following, the final mAh value should be close to reality:
1) Keep brightness at maximum during the test. Don't try to tweak it after the test starts.
2) Same for all wireless connections. Phone, wireless, bluetooth etc. They must be all disabled. You tweak it, you get lower mAh result.
3) In case you overclock your CPU, don't do it during battery test. Set it to default stock speed, default governor. If you leave it overclocked and on performance governor for instance, you will see a lower mAh result.
4) Forget the standard and fast tests and prefer the full test from 100% charge. Larger drain cycle is better for reflecting the whole capacity. Faster tests can also calculate results but these would be just a sample area of the whole battery cycle.
5) Don't mess with the device until the end of the test. Let it drain peacefully :)

The main advantage of this app is measuring the capacity through a drain cycle which is a better simulation of "capacity". Battery Monitor Widget is not too bad in measuring mAh value either but it uses the charging cycle.

However, do not forget that all batteries are rated according to constant 0.1 C discharge rate by their manifacturers, like 250mA for a 2500mAh battery. Thus, a standard capacity mesaurement requires a test of 10 hours exactly, which is too long to spend for end users without using the device.

Hopefully, Nova goes faster than that, like 2-3-4 hours for a full test, at 0.3-0.4C discarge rates. Although the duration looks bearable, the pay-off is probably a result below the battery spec. The more is the discharge rate, the less is the capacity measured as a basic rule!

Even a brand new battery may give lower mAh than what's written on it's label. Don't be surprised and remember that 5% to 15% less is just usual even for a new battery.

The app certainly needs to use a current value as a key parameter, either via internal sensor (better case) or from the developer's database (when no real time value). The calculation method is not hard to decrypt at all. It tries to measure the average of the time needed to lose 1% of the charge during the whole test and multiplies this by 100 to estimate total battery time. This total expected time of a full discharge from 100% to 0% is then multiplied by the average current value to obtain hours x milli amps which is exactly the mAh value we need to know.

That's why the mA value is certainly necessary and without it, no mAh value will come but only a test time. If your device can't report the mA by itself and if the device is not found in the database either, you can just uninstall Nove tester.

My 1 year old N7100 Galaxy Note II has a 3100mAh. It was measured at 2600 mAh during full test. The mA was not reported by the OS, alhough i know it exists somewhere in the OS becaue BMW can see it. Nova could not. No worries anyway, the database value of 859 mA was used to calculate a result. By using above formulation i was able to calculate the same mAh. If the result is not accurate here, the only thing to blame would be that 859 mA value. If the database average value is correct, the result is accurate.

That why you should respect the test conditions, especially if you have to use a database value. They come from identical devices with max brightness, flight mode, stock cpu etc.

Try and see for yourself.

PS: I mention mAh value as capacity unit above. However it's not the correct unit by definition but people understands this better than Wh which is the correct capacity unit. Please know that a 3100mAh battery is always a 3100mAh battery until death. Read it like speed. What matters is the distance, speed by time, which is Watt.hours for batteries. They lose WH and not mAh, in fact.
 
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fierogt42

Senior Member
Mar 10, 2012
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I hate to necro, but this thread came up on Google and I wanted to add that if you look up the internal technical specifications on batteries (for LG for example), they often state the maximum charged capacity is 85%.

That means a 2100 mAh battery is 1785 when brand new and charged to 100% at perfect "health"!

Modern smart phone batteries are intended to operate this way. If you're showing lower than 85% advertised capacity, you have definite "wear" or "aging" causing diminished charging capability.
 

Tinderbox (UK)

Senior Member
Mar 31, 2010
2,275
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England, UK
Well i ran the Nova Battery Tester on my HTC Evo 3D and my Samsung S3 and after running for over an hour it said the battery capacity on both phones was still at 100% and had lost 0% capacity, though i had expected a bit of capacity lost because the battery`s are a couple of years old, so is app just showing the stock battery capacity as it has to connect to the internet to download the phones profile if one exists.

Nova Battery Tester is no longer on Google Play i wonder why, but it can be found if you search for it , the real file is 1.36mb in size, one website had it at 9mb (most likely malware) so be careful.

John.
 
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issy_i

Senior Member
May 22, 2011
335
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Flushing
testing my Note2 right now with Nova battery Tester, doing a full test from 98%-5%. This battery is the original one deliverd with the phone in 2012..
will post result in a hour when done!