Battery recharging anomaly

[weedkila]

Does anyone have any idea why the power adapter in a Macbook Pro would show an orange light at start up, indicating that the battery is being charged, when the battery was already fully charged (green light) at shut down just a few hours earlier? After restarting the light remains orange for about 40 - 50 mins before it changes back to green.

After shutting down my computer I have a habit of switching off the power supply, but when in use I tend to use it like a desktop in that it's always connected to the mains. When going out I make sure to shut it down and do not leave it in sleep mode. I can't see any reason why the computer would use the backup battery to any extent during shut down, especially draining it so much that it takes 40+ minutes to recharge.

This orange light/recharge anomaly shows up maybe every 2 or 3 weeks, otherwise the adapter light always shows green at start-up, even after a day of non-use. My mac is about 4 years old and am using OS X 10.6.8.

 

[GGJstudios]

After shutting down my computer I have a habit of switching off the power supply, but when in use I tend to use it like a desktop in that it's always connected to the mains.

It's very bad for a battery to always have it plugged in when your Mac is in use. You should regularly run on battery power to keep it healthy. Also, there's nothing wrong at all with leaving it plugged in after it's fully charged, as long as you're not doing it all the time. There's also nothing wrong with using sleep mode instead of shutting down. Install iStat Pro (free) or iStat Menus ($16) to get accurate readings of your battery health, cycles, and much more.

Run on battery whenever you need to and plug it in whenever you can. You can plug or unplug any time you need to, regardless of the charged percentage, and you never need to completely drain your battery. Just make sure you don't run on AC power exclusively, as your battery needs to be used regularly to stay healthy. The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.

Apple Notebook Battery FAQ​

 

[weedkila]

Thanks for your reply and the link which I read. Unfortunately the info you gave still did not answer my question as to why the battery intermittently recharges after a relatively short shutdown period. As as I see it any system usage of the battery during shutdown, such as the clock, should not later cause it to have to recharge for as long as 40-50 minutes.

I am using a 24" monitor which is powered independently of the mac. I agree that it is a good idea to sometimes use battery only, but for some reason when I disconnect the power adapter and use battery only it causes the computer to go into sleep mode within 5 seconds. If I disconnect the monitor and use the MBP screen it works normally under battery power. (Computer and Display sleep are set to 30 minutes in the Battery section of the Energy Saver pane and the 3 boxes are all unchecked). I did that to try to recalibrate the battery.

 

[Weaselboy]

Thanks for your reply and the link which I read. Unfortunately the info you gave still did not answer my question as to why the battery intermittently recharges after a relatively short shutdown period. As as I see it any system usage of the battery during shutdown, such as the clock, should not later cause it to have to recharge for as long as 40-50 minutes.

I think what you are seeing is normal. The battery will just naturally lose a little charge even when the system is shut off.

I am using a 24" monitor which is powered independently of the mac. I agree that it is a good idea to sometimes use battery only, but for some reason when I disconnect the power adapter and use battery only it causes the computer to go into sleep mode within 5 seconds. If I disconnect the monitor and use the MBP screen it works normally under battery power. (Computer and Display sleep are set to 30 minutes in the Battery section of the Energy Saver pane and the 3 boxes are all unchecked). I did that to try to recalibrate the battery.

That is normal also. The system won't run the external display when only on battery power. I agree this is annoying. It would be nice to be able to just disconnect the charger once in a while and exercise the battery without having to disconnect the monitor also. I use a Apple Thunderbolt display with a Macbook Air and it works the same way.

 

[weedkila]

Weaselboy, thanks for the feedback re the monitor.

Still not sure whether the battery suddenly discharging like that is normal but think I'll keep an eye on System Profiler > Power for a while to see what happens. Currently it's:

Battery Information:
[…]
Charge Information:
Charge remaining (mAh): 4390
Fully charged: Yes
Charging: No
Full charge capacity (mAh): 4514

Health Information:
Cycle count: 9
Condition: Normal
Battery Installed: Yes
Amperage (mA): 0
Voltage (mV): 12436