Battery capacity development over a week, and a year

[ungua]

I have a Dell XPS M1530 that turned one year last week. During that week I made screenshots of the CPUID-information delivered to me. I use this wonderful piece of software to monitor the temperature of the notoriously hot computer, and after mye last harddrive-crash I found the new version contains information about the battery, too. I wonder: How can the current full charge capacity swing so much on a day to day basis? And is it normal that the battery has lost 16% of its capacity during the first year? Even though lithium batteries are not supposed to have a memory-effect, I still cling to the "empty first, load thereafter"-strategy, and have had good success with that on cell phones. But the Dell disappoints me (as it does in any other respect anyway - 2 new harddiscs, new motherboard, and a new battery already in week one are the results of the first year's use and maintenance need. Never needed maintenance on any PC or notebook ever before, PC-use since 1994).

Best regards
ungua

 

[nismo91]

16% loss after one year is reasonable. ok, so not all battery manufacturers have "accurate" battery wear level but i will post mine: i got 2 laptops with accurate battery so far (acer TM4000 and 5930G)

the latter, was bought in early dec 2008. so today, after about 1.5 years it has 31% wear level. now = 48988mwh. was = 71040mwh.

in my case, the level get worse if i use the laptop everyday on battery. once I kept the battery and use the laptop as a desktop replacement the level barely increase. one tip to keep it is that to "calibrate" your laptop battery as often as possible. In some cases I successfully decrease the wear level by doing that. It's clear that short discharge of battery actually worsen the age of the battery itself.

I saw few sony vaio & toshiba laptops, with battery wear level at 0% but battery dies within 5-10 minutes of usage.

 

[ungua]

Wow, 31% after 18 months is a lot, in my eyes! They can't be engineered like that? I bought the XPS as a desktop replacement, but its awful reliability record makes that impossible. So I just use it as a walkaround-notebook at home, the change happened only in march.

I am also thinking about the implications for other batteries: If my cell phone would lose one third of its capacity within 18 months, I would ask for a replacement. What about those Tesla-cars that run on notebook-batteries - can't be worth the buck?

 

[s400py]

my lenovo battery has worn down to 76%, and I've had the laptop for roughly 8 months now. This is indeed quite annoying.

 

[ungua]

That was a ridiculous wear! So how does the Tesla car company with its laptop battery driven car complain that to customers? "Sorry, but it's normal that your cars maximum mileage decreases by 25% per year"...? My crappy Dell is down to 65934mwh maximum capacity, that's a 24% loss. No competition for you Lenovo, though.

 

[ungua]

Here we go again...

For a week I haven't restarted the computer, just put it in "waiting mode" or "sleep mode". Full charge capacity moves between 76 and 87% of battery capacity. Though I just discovered the high value, 65xxx has been the norm over the last couple of weeks.

... A good reason not to buy a Tesla roadster, I guess!

 

[nismo91]

Well hello again, just in the right time i was just running "Battery Eater" for the first time, after 19months with my current laptop. With the old laptop, I did not know that I have to calibrate the battery often to keep the percentage level accurate. I also have tested few 2-3yo laptop and it always give the same 'inaccurate' result.

Thanks to the calibration, my current laptop has a decent accuracy, although the wear level seems to be 35% right now. Checking with the full charge level I do understand that basically the more you use your battery the faster the full charge level drop but it's acceptable, considering laptops batteries are meant to be used isn't it?

laptop spec:
Intel P8600, 4GB RAM, 320GB HDD, 9600M GT GDDR3, Vista HP 32bit
Scheme: Power Saver
AERO transparency: OFF
CPU: Min-Max 0%
GPU: Max Power Saving
Wi-Fi: Max Performance
LCD: 100%
Activities: Streaming movies online with wi-fi
Bluetooth: OFF
External USB devices: NO
Stock Speed for CPU & GPU: YES
BatteryEater Mode: Idle

report:
Main Battery Info
Device Name AS07B32
Manufacture SANYO
Serial # 6284
Unique ID 6284SANYOAS07B32
Chemistry Lithium Ion
Temperature Termal Control Not Present
Designed Capacity 71040mWh
Full Charged Capacity 46931mWh
Designed Voltage 14.4V
Current Voltage 13.675V
Manufacture Date 0/0/0
Cycles Count 0
Cells count 4
Force charge support Not Supported
Force discharge support Not Supported
Results
Total time 1:30:27
Discharge rate (maximum) 4294949136 mWh
Discharge rate (average) 4277825562 mWh

Notice the inaccuracy after it reaches 10%. Well, the battery aren't used daily (only in some occassions) but for 19mths old I think it's 'uniform' enough. I have run BatteryEater on other old laptops and got disappointing results: the graph is not uniform / flat, it can suddenly drop from i.e. 20% to 5% and have flat 5% to 4% for 30min and decrease uniformly again. Example:

((Google Image for : Battery Eater Discharge Graph)) and you know what I mean.


Try it, download here