MacBook Pro 13" Mid 2012 battery: concerned

nicolunacba

macrumors newbie
Original poster
Aug 9, 2012
2
0
Hi people,

I've bought a new MBP a week ago. I didn't spend the time I wanted with it, but I'm finally using it.

The first time I used it, I saw in iStat Pro that the battery life was 98%. I was not worried because it was its first use. Today I decided to check it again and I saw battery life is 92% now! Why?!

Also, the battery remaining time of Lion (not Mountain Lion) is pretty variable! While I am writing this, I had 5:35 and 4:45 time remaining in just 5-7 minutes :confused:

Finally, checking system information I am noticing something (my system is in spanish so I wrote some translations):

Información sobre la carga:
Carga restante (mAh): 4398 (Remaining battery)
Totalmente cargada: No (Fully charged?)
Cargando: No (Charging)
Capacidad de plena carga (mAh): 5297 (Full charge)
Información sobre el estado:
Número de ciclos: 4 (Cycles)
Condición: Normal (Condition)
Batería instalada: Sí
Amperaje (mA): -808 (Amperage)
Voltaje (mV): 11927 (Voltage)

Is 5297 a normal mAh for a full charge? Is it normal to have a negative amperage? (not plugged)

I am really concerned about battery life. Now, it's tooking 1 hour to use aproximately 20% of battery.

Help me to take off this fear. Thanks!

Regards!

PD: Finishing this I have now 5:02 of battery time
 

T5BRICK

macrumors G3
Aug 3, 2006
8,095
2,057
Oregon
Everything looks ok to me.

Keep in mind that it isn't necessary to unplug the laptop when the battery is full. It is smart enough to stop charging at that point and just run off of AC power. This will help keep your charge cycles low. Also, just remember to run your battery down at least once a month; you have to use it to keep it healthy.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,419
759
The first time I used it, I saw in iStat Pro that the battery life was 98%. I was not worried because it was its first use. Today I decided to check it again and I saw battery life is 92% now! Why?!
It is perfectly normal if your battery health (maximum capacity) is more or less than 100%, even when brand new, or if it fluctuates up or down over time. For further details, read the CHECKING STATUS AND HEALTH section of the following link.

Also, the battery remaining time of Lion (not Mountain Lion) is pretty variable! While I am writing this, I had 5:35 and 4:45 time remaining in just 5-7 minutes :confused:
From the BATTERY LIFE FROM A CHARGE section of the following link:
  • Your "time remaining" indication is an ever-changing estimate, based on the current workload of your system. It will fluctuate up and down from minute to minute as your power demands change. It is not perfectly accurate, but only an estimate.
I am really concerned about battery life. Now, it's tooking 1 hour to use aproximately 20% of battery.
There are many factors that impact your battery life. See the BATTERY LIFE FROM A CHARGE section of the following link for details, including tips on how to maximize your battery life.

This should answer most, if not all, of your battery/charging questions:
 

nicolunacba

macrumors newbie
Original poster
Aug 9, 2012
2
0
Your battery health is referred to either as a percentage or in mAh and represents your current full charge capacity (mAh) as compared with the ideal full charge capacity (100%). Be aware that battery readings are not 100% accurate and they fluctuate up and down, so if your brand new battery health is somewhat more or less than 100% or if it fluctuates up and down over time (100%, 91%, 95%, etc.), don't worry. It will not only decline. For example, if your battery health is 92% one day, it could be back up to 97% a few days or weeks later. It is not a one-way fluctuation. This is completely normal.
Uhm, okay. Some people told me the same. They said as time passes and charging that status will be ok. But I am not sure.

I will try to use it today. I don't use my mac very often because I am working all day. I think I only used about 6-7 hours since I have it.

One friend told me she recovered the battery life of her notebook (Dell) by using it with the power adapter plugged. Do you recommend me to do the same?

Oh, and thanks for the help and info! :D

Regards
 

GGJstudios

macrumors Westmere
May 16, 2008
44,419
759
One friend told me she recovered the battery life of her notebook (Dell) by using it with the power adapter plugged. Do you recommend me to do the same?
No, running on AC power will not restore lost battery capacity. You can certainly use your Mac while it's plugged in, as long as you unplug and run on battery for a while every few days, to keep the battery healthy.