Macbook Pro 15" 2012 battery drains while sleeping. What to do?

Perhaps a bad battery? I've let my 15 inch sleep for a week once with little battery drain.

Reboot without opening your previous programs automatically again.

Try it over night again. If your Notebook loses more than lets say 10%, which is already a lot, your battery is bad and you should bring it back.

phillyfan9090 said:

I got my 15" 2012 MBP retina from the apple refurbished store a week ago. Its had decent battery life but the problem is that whenever I put it to sleep, the battery drains fairly quickly. What do you guys recommend for saving battery while sleeping.. and overall energy consumption

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Your MBP should consume about 1% of battery for every hour of sleep. If it's using more than that, it's very likely that it's not remaining in sleep mode for the entire time. Check to see what you have running that could be waking it up.

Follow every step of the following instructions precisely. Do not skip any steps.

1. Launch Activity Monitor
2. Change "My Processes" at the top to "All Processes"
3. Click on the "% CPU" column heading once or twice, so the arrow points downward (highest values on top). (If that column isn't visible, right-click on the column headings and check it, NOT "CPU Time")
4. Click on the System Memory tab at the bottom.
5. Take a screen shot of the entire Activity Monitor window, then scroll down to see the rest of the list, take another screen shot
6. Post your screenshots.

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. 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.