Battery problems on a Macbook Pro Retina 15" (mid 2015)

[Lovecraftin]

So a couple of days ago I bought a barely used/like new Macbook Pro Retina 15" (mid 2015) for 1000€, a bargain. Once I checked the coverage it still had on the Apple website I found I still had the Apple 1 year warranty until 17/02/2017 which means this computer isn't even 1 month old. Well, that also explains the 11 cycle count on the battery.

Thing is, the battery seems to be a bit weird. First of all I notice I'm having lower battery life than I expected (Apple says it's up to 9h) and I'm getting 6 hours tops with screen brightness under 50%, surfing on Safari with no other apps open. I've checked the Activity Monitor multiple times, I stopped using Chrome, I think I'm kinda obsessed with this to be honest. I did a reset on the SMC, I've been "exercising" the battery, today I even dropped it low to 1% after charging to 100% and then I charged it back to full. Still the same performance.

Also, the estimated time is always jumping up and down, even if I'm doing the same task with the same apps open. It can start high as 15 hours after I remove the charger and I'm not doing anything special, then it drops to 14, then to 12, then to 8, 7 to finally 6 where it kinda stabilises. Then it goes down to 5, then up to 5:30, then to 4:30, then to 5 again. It's incredibly annoying. And as I said above, it's not like I'm changing my activity, I'm actually trying keep always the same apps open just to test this as I'm typing.

Another thing I noticed.. I downloaded coconutBattery to check the battery. The first time I used it, the day I bought the mac, it said the battery's health was at 96% which is low for a 11 cycle battery on a less than 1 month old mac. Today after I did the "calibration" thing I checked and it's up to 98,5% which I hope means that helped. Maybe a calibration every month might do the trick? Thing is, even today, the battery is still giving me random estimates, half an hour ago it was at 4:00 and now it's up to 5:45 and I'm doing the exact same stuff.

Do you think it's worth it to take this mac to a repair center?

Thank you, guys!

PS: I'm running El Capitan. I haven't done a reinstall since I first bought the mac, maybe that would help?

 

[bfid111]

There is nothing wrong with your computer

 

[Lovecraftin]

There is nothing wrong with your computer

So me getting 3 hours less than advertised by running this computer at almost minimum settings, barely any programs open and getting absurd time estimates is normal?

Also, forgot to mention this, do you get more battery life for using a different display resolution scale? Would using the default one make me get more hours out of the battery?

 

[snaky69]

So me getting 3 hours less than advertised by running this computer at almost minimum settings, barely any programs open and getting absurd time estimates is normal?

Also, forgot to mention this, do you get more battery life for using a different display resolution scale? Would using the default one make me get more hours out of the battery?

It specifically says "up to". You said it yourself right in your first sentences. Resolution will have zero effect.

Apple's estimates have bluetooth off, screen at about ⅓ brightness, safari browsing on sites containing no flash, and having a word document open. Time machine off. Unless you meet all these, you're not likely to get the estimate.

Edit: Oh, and I really think you have way too much free time on your hands to be this obsessed over something so trivial. If it lasts long enough to get you through your work day, then it's fine.

 

[afluriach]

and I'm getting 6 hours tops with screen brightness under 50%

It's worth pointing out LED power does not scale linearly with apparent brightness. (If this seems surprising, remember that your eye's response to brightness is actually logarithmic.)

According to this post on changing the brightness scaling, these are typical PWM scaling numbers for the brightness.

00110000 00210029 00340042 00530069 008700ac 00d30103 013e0187 01e20252 02de038f

LED power use is linear with PWM, so you can see "50%" brightness is actually almost 8 times as much power as the minimum brightness.

The display backlight definitely can use way more power than the CPU does in its lowest power state.

At least on the 13-inch retina, I typically beat battery life estimates for browsing mostly static content (remember that buggy JS can waste CPU just as easily as Flash). But that's usually at minimum (or maybe a quarter) brightness.

It's also worth pointing out that the battery health metrics don't tell you much. If the laptop was left in a hot car for a month with the battery at 100%, then the battery may very well have lost 5-10% of its capacity.

I don't know how different the new Li-Pol batteries are, but traditionally with Li-Ion batteries, leaving them at a full charge causes the cathode to oxidize—and of course heat just makes the reaction happen faster. This is why batteries noticeably lose their capacity when they are just kept on charge.

 

[Samuelsan2001]

It's within warranty take it to Apple to check it out, either it's fine and you expect and obsess far too much or it's not and Apple will fix it.

 

[Hewthetitan]

The iPad Air 2 I have here is immune to running out of batteries. It's impossible, it exceeds the specs listed. For the device costing $1000 more to fall short by over 33% is disconcerting... Yet my rmbp 15" can't get 6 hours if it's life depended on it.

Returned it today. Very sad.