Macbook battery draining while plugged in and idle?

The charging circuitry takes the battery to 100% charge, then shuts down and the unit will run on the chargeer even while in sleep mode. The battery does trickle discharge, all batteries do, even while on the charger. When the battery charge level gets down to something in the range of 93-95% charge, the charge circuitry kicks in and tops off the battery, then shuts off again. Cycles that way as long as it is plugged in.

It sounds unusual that the machine would draw down the battery almost completely while in display-sleep mode with just something running in the background, unless that something was pulling in the discreet gpu in addition to the normal gpu. Not many processes demand that kind of power...unless you had a power loss on that circuit??

Check the battery condition: apple menu, About This Mac, More Info, System Report, Hardware, Power and what is the battery Condition, Capacity, Charge remaining, Cycle count, and Voltage.

That all looks pretty normal...you want to see the Condition as Normal, otherwise there may be a problem. Capacity of 6928 mAh is essentially an as-built capacity so that is good, and only 13 charge cycles, you haven't used this MBP off the charger very much. Batteries last longer if they get period use, might want to disconnect the MagSafe connector at least a couple times a month or so, and run it down to 50% and then recharge. Exercise is good for batteries, just like people 🙂

The voltage is right where you want it in the 12 to 12.5 volt range so that is good, all cells are healthy.

Overall that looks like a good battery, I would just exercise it off the charger a little more...if you weren't running something really cpu/gpu intensive earlier, who knows, maybe the battery was just expressing it's displeasure at not getting to play 😝

Try an SMC reset. Justifications for doing that are many but include the following:

Power

The computer doesn't respond to the power button when pressed.

A portable Mac doesn't appear to respond properly when you close or open the lid.

The computer sleeps or shuts down unexpectedly.

The battery does not appear to be charging properly.

...

Will I lose and settings, or will any of my preferences be lost? Thanks!

No, nothing will be lost at all.

Ralph,

If you would be so kind as to offer your expert opinion of my battery life I would greatly appreciate it?

Charge Information:

Charge remaining (mAh): 3096

Fully charged: No

Charging: No

Full charge capacity (mAh): 4243

Health Information:

Cycle count: 149

Condition: Normal

Battery Installed: Yes

Amperage (mA): -1148

Voltage (mV): 11783

Thanks in advance for your help!!

Hi Thunderfan,

What machine do you have and vintage? Reason I ask is the capacity is low for a MacBook Pro of current vintage, but would be fine for an older model or MacBook Air or MacBook. Current MBP batteries are usually in the 6000-7000 mAh range. The older machines and others noted are fine below 5000 mAh.

Your cycle count should be ok, again with the same comments just made. Apple has increased the ratings for the newer batteries to 1,000 cycles, while many of the older model machines had ratings in the 300-500 cycle range.

Keep in mind that cycle life is a statistical thing, the predicted life is the peak of a normal, or Gaussian, distribution. Some will fail sooner, some later. So when the predicted life is 1,000 cycles that is a norm and not an individual guarantee.

Voltage is ok at 11.8 volts, again noting the model and age, more typical is 12 volts, but that does vary with load and services you have running. Not something to worry about, especially since the condition is rated as Normal.

I would not worry about that battery unless you are having problems you have not noted.

As a final note: batteries are consumable items, eventually they need to be replaced just like in a flashlight or automobile. Exercise them periodically by unpluging the charger, run them down a ways, maybe half or so, and recharge. Like people, they do better with regular exercise 🙂

Ralph,

Thanks for the quick follow-up🙂

I have a late 2008 MBP 2.66 Dual Core I purchased in early 2009. I'm not sure if this qualifies as an older model that has the lower cycle range with the low capacity? If so, will I need to check the battery condition periodically to see when it fall outside the normal range before I replace?

Kindest Regards

This knowledge base articlegives projected battery life cycle counts for the Apple portables.

A 2008 machine looks like it will be in the 300-500 cycle range depending on the exact date of the MBP. I would not fixate on the battery information unless something seems to be going wrong or you start getting messages to service the battery. Often the first time that pops up people manage to clear it by taking the battery through a full charge cycle, i.e., discharge to the point the MBP shuts off, do not force it to restart, and charge fully before using again. That seems to be clearing the service battery message the first time. Haven't heard from people getting repeated messages that did not end up getting a new battery.

BTW, just noticed when I went to the knowledge base area that Apple store prices on new batteries seem to all come in around $129 (US), not that you need to worry about that right now...just a little tid bit of info 🙂