Post Your Air Battery Status

[NC MacGuy]

Per iStat:

Battery Health 93%
Cycles: 29

Per "About this Mac"

Battery Information:

Amperage (mA): -1051
Voltage (mV): 7631

Is it odd that the Amperage is negative?

Anyway, I generally use it on battery until it needs to be charged, then let it charge overnight... I usually shu it down when charging (seems to do it quicker) but I leave it on and just let it sleep when it is in my bag... I usually charge it maybe every 3-4 days...

I usually just use it for email, web and the occasional Parallels/WinXP when i need to admin my client's servers.

Amperage shows up as a negative when running from battery. If you plug in your charger and restart system profile you should see it go positive.

 

[somonster]

Here's my guess based on sookainians info.



I think that the health is based on the ratio of charge remaining when fully charged and the full charge capacity. In sookainians case it's the following:

4928 / 4985 = 0.98856 ... or 99%

So it's the percentage of the full charge you're actually getting. So with my 97% I'm only getting 97% of my batteries full potential.

My Full Charge Capacity is 4951 mAh
97% Health
Last charge was up to 4802 mAh (appr)

I'm not sure when iStat or System Manager refreshes these so it's obviously not a completely accurate reading, but kind of a guideline to let you know if something might be wrong.

I have to state that this is all theory though, so don't go quoting this as fact.

wow. that was more than i can wrap my brain around at this time.
thanks for the input - excellent thought. I'll have to go back and review some of the other numbers and see if your theory pans out.

if that is a case, then i suppose health is a *relative* term (and perhaps an indicator of much your battery likes how you treat it), not an absolute measure of a battery's "endurance."

thanks again.

you guys are *swell*

 

[chewbaccacabra]

I guess I am returning mine tonight. Still in the 14 day window. I used it last night on the power adaptor because the battery hadn't held a charge. The battery is now at 0% health and 5 cycles.

 

[SthrnCmfrtr]

wow. that was more than i can wrap my brain around at this time.
thanks for the input - excellent thought. I'll have to go back and review some of the other numbers and see if your theory pans out.

if that is a case, then i suppose health is a *relative* term (and perhaps an indicator of much your battery likes how you treat it), not an absolute measure of a battery's "endurance."

thanks again.

you guys are *swell*

Yes: health is current max capacity divided by factory max capacity.

Different types of batteries prefer different treatment. The old laptop batteries preferred to be discharged and recharged fully. The more recent batteries (in MacBooks, for instance), prefer to be discharged and recharged partially, which fits better with the "desktop replacement" use that most laptops get these days.

As an example, I had a white MacBook that I bought at the same time as my wife's black MacBook. She took hers to work, drained it, and brought it home and charged it in the evenings -- and did this very often. I used mine nearly constantly but only had it unplugged for short periods of time.

The result was that my cycle count was nearly three times hers, but I had over 100% health (because my battery's capacity actually improved over the factory capacity) and her battery's health is, IIRC, about 60%. When I sold my MacBook a couple months ago it still had 99+% health.

Our batteries' healths would be reversed if we were using the old Ni-Cad batteries or the Li-Ion batteries (IIRC). With Lithium Polymer, the battery's optimal cycle has evolved to be closer to my pattern of usage rather than my wife's.

So keep that in mind.

(Also, a cycle on a modern battery does not count the number of times the battery has been fully discharged and fully recharged; it counts the number of times that the battery has been fractionally discharged and fractionally recharged. In other words, if I discharge my battery 10% and recharge it 10%, and do that about ten times, that's a cycle. It might seem obvious, but I've seen some people get confused by it -- assuming their power supply was ****ed or something -- so I thought I'd mention it.)

 

[Santa Rosa]

Anyway, I generally use it on battery until it needs to be charged, then let it charge overnight... I usually shu it down when charging (seems to do it quicker)

The one time I tried to charge my Air when it was off it refused to work and the orange magsafe light went out!!

The battery on it seems to be good though as I can get about 5 hours out of it.

 

[hildegueden]

Health: 97%
Cycles: 39

I’ve never been able to get the 5h (4h max.). Could be because I live in a hot country?

 

[ayeying]

Health: 96%
Cycle: 4

Battery life: 4.5 hours last night.

 

[fredrickyoon]

Health : 95%
Cycles : 37

Should I get worried? I've had 37 cycles right now according to iStat and the battery health has hovered between 94% to 95% these days.

I thought that it was supposed to get better?

I've callibrated it twice so far, had it since February 08.

Thanks

 

[awvan]

Cycles: 5
Health: 100%

I have calibrated once (as soon as I got my MBA) and consistently get 4 hours+ of battery life. Haven't really hit the 5 hour mark, though with WiFi and Bluetooth turned off and the screen dimmed quite low I think I could get there.

 

[Jimmie Geddes]

97%
53
yes

 

[Suncusser]

Week2 MBA

41 cycles
96% Health

 

[BryanLyle]

32 charges
99% health

Painfully slow recharge times.... My only complaint about the MBA. If I unplug it and use it for 30 minutes, it takes almost 90 minutes to recharge to full capacity. Booooooo.

 

[ubercool]

Battery Health: 94%
Battery Cycles: 88

 

[buccsmf1]

couple months ago i was at 96%. Now im up to 98% on 15 cycles

 

[rost12]

Cycles: 49
Health: 96%

Health dropped to 93% within a week of purchase, then slowly crept back up.

 

[stsanford]

Battery Health: 95%
Battery Cycles: 90

 

[K4VKS]

sorry for this potentially stupid question - how do u calibrate ure battery? what exactly does this do/mean?

Health - 98%
Cycles - 7 (new mba)

 

[hildegueden]

Battery Health: 96%
Battery Cycles: 51

 

[ayeying]

96%, 17 cycles.

 

[Santa Rosa]

Results So Far

Big up to everyone that has submitted so far.

Have taken all the data and made a really simple graph Cycles vs Battery Health. Will try and update it if I get a chance if you post in some more data. So here it is (gonna have to click on it for a larger has come out too small on here!!):



So what do you all make of that??

 

[ayeying]

so our battery's on crack and cant maintain a steady health %