I am glad I got the 11"inch I-5 
with 512SSD/8GB
I7 has been having a lot of bad battery issues reported through this forum
with 512SSD/8GB I7 has been having a lot of bad battery issues reported through this forum
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Battery Life i5 vs i7, anything definitive yet?
- Thread starter Jazwire
- Start date
- Sort by reaction score
I don't know that it's useless - you still get an idea of % difference. Sure, saying "an hour less time" isn't useful, but saying "23% less time" is.
I am glad I got the 11"inch I-5
I7 has been having a lot of bad battery issues reported through this forum
Yeah, I've got an i7 one arriving on Monday and I'm wondering if I should swap it before opening it...
Last edited:
Yeah, I've got an i7 one arriving on Monday and I'm wondering if I should swap it before opening it...
Open it. You get 14 days from deliver to return whether or not you open it.
I got the 13" i7 model (8GB RAM, 512GB HD), and it definitely doesn't get nearly the battery life the reviewers are reporting for the i5 model. It still gets the best battery life I've ever gotten from a laptop, though, and I'm glad to have the more capable processor. Overall very pleased with the purchase.
my i7 8/512 is giving me about 7 , maybe 8 hours of real world use with screen turned up 2 clicks below max, wifi on and me doing a lot of futzing around with various software.
I consider that pretty good. Anyone who takes manufacturers batt life marketing estimates as anything more than wishful thinking in the real world is ... well ... is not a good consumer.
I consider that pretty good. Anyone who takes manufacturers batt life marketing estimates as anything more than wishful thinking in the real world is ... well ... is not a good consumer.
I just ran out of battery with my ultimate 13" i7 MB Air. Clocked usage time was 12h 15 mins. It included indexing the whole migrated hard drive and updating and using (about 20 minutes) 2 virtual machines in Parallels (Ubuntu and Win 8). Rest of the time was surfing the web, using terminal with SSH and also driving 3 benchmarks with Geekbench 2.
BTW, Geekbench 2 with 32-bit test produced almost exactly 7500 points, in comparison to 7007 for the 2012 ultimate model. That is about 7% more power. That obviously does not tell the whole truth, but it gives some indication, that in wide variety of CPU intensive tasks, the new Haswell performs just a bit better while also saving on the wattage.
BTW, Geekbench 2 with 32-bit test produced almost exactly 7500 points, in comparison to 7007 for the 2012 ultimate model. That is about 7% more power. That obviously does not tell the whole truth, but it gives some indication, that in wide variety of CPU intensive tasks, the new Haswell performs just a bit better while also saving on the wattage.
Thanks for the report! So you had parallels running that whole time? I've heard reports that parallels wrecks battery life down to 4-5 hours!
No, I didn't have Parallels running except for the duration I needed the virtual machines (which was quite a small period of time). If I had kept it running all the time, battery life would definitely be significantly lower. I might do a test soon with my Ubuntu VM to see, how running a VM drains the battery. But so far, I have been really impressed with the i7 battery performance!
The i7 doesn't run much faster by default than the i5, but it can turbo a higher clock speed than the Core i5.
If you're running a high CPU workload that never lets up in a continuous loop, the i7 is going to die quicker than the i5. Active power is greater at higher frequencies (assuming everything else remains the same) and with no chance to get to sleep the i7 will eat through the battery faster than the i5.
Where the i7 stands a chance however is in workloads where you aren't running the CPU at full tilt all of the time. The i7 needs tiny, tiny, tiny fractions of a second of idle time to throttle down and go to sleep. It's in these sleep states that it'll draw very little power and avoid being a major consumer of the battery. From the CPU's perspective, it wants to finish its work as quickly as possible so it can get back into its really low power idle states.
For workloads with balanced periods of load and idle time, the i7 should be able to at least equal the battery life of the i5. Short bursts of instructions can execute up to 25% faster on the i7, allowing it to go back to sleep that much quicker. Any energy expended from running at higher clock could be saved by spending more time at idle.
The other advantage is the larger cache. A larger cache means a higher likelihood of finding data in that cache, which saves trips to main memory. Anytime you go off-chip for data the power penalty is tremendous. You have to fire up a powerful memory interface, drive requests back and forth over a high speed bus and actually pull the data from DRAM. The entire process is far more power intensive than just grabbing data from the CPU's on-die cache.
Personally, I'll be going for the i7/8/256 varient of the MBA11". Battery life varies depending on how the CPU is used. Asking others how the battery life fares for them will not give any indication of what you will receive yourself. The i7, although using more power, should, in theory, finish the task quicker, and hence go back into its low power idle state quicker then the i5, thus saving power. The battery life for both models should, in theory, be more or less equal unless you throttle the i7 at its high clock speed for long periods of time.
If you're running a high CPU workload that never lets up in a continuous loop, the i7 is going to die quicker than the i5. Active power is greater at higher frequencies (assuming everything else remains the same) and with no chance to get to sleep the i7 will eat through the battery faster than the i5.
Where the i7 stands a chance however is in workloads where you aren't running the CPU at full tilt all of the time. The i7 needs tiny, tiny, tiny fractions of a second of idle time to throttle down and go to sleep. It's in these sleep states that it'll draw very little power and avoid being a major consumer of the battery. From the CPU's perspective, it wants to finish its work as quickly as possible so it can get back into its really low power idle states.
For workloads with balanced periods of load and idle time, the i7 should be able to at least equal the battery life of the i5. Short bursts of instructions can execute up to 25% faster on the i7, allowing it to go back to sleep that much quicker. Any energy expended from running at higher clock could be saved by spending more time at idle.
The other advantage is the larger cache. A larger cache means a higher likelihood of finding data in that cache, which saves trips to main memory. Anytime you go off-chip for data the power penalty is tremendous. You have to fire up a powerful memory interface, drive requests back and forth over a high speed bus and actually pull the data from DRAM. The entire process is far more power intensive than just grabbing data from the CPU's on-die cache.
Personally, I'll be going for the i7/8/256 varient of the MBA11". Battery life varies depending on how the CPU is used. Asking others how the battery life fares for them will not give any indication of what you will receive yourself. The i7, although using more power, should, in theory, finish the task quicker, and hence go back into its low power idle state quicker then the i5, thus saving power. The battery life for both models should, in theory, be more or less equal unless you throttle the i7 at its high clock speed for long periods of time.
If you need absolutely the best battery life go for the i5, if you need a little tiny bit of extra power and less battery life go for the i7, it is pretty clear now.
Yes and no.
The i5 will most certainly give the best battery life - completely agree - although when performing non-intensive tasks, like checking emails, browsing the web, word processing, etc, the i7 will be on par when it comes to battery life. The difference would be minutes, not hours, and hence a non-concern. Heat would also be a non-concern, due to the light usage.
I wouldn't call the difference between the i5 and i7 tiny though. You have more cache as well, which is also an important factor to consider, as highlighted in my previous post - its not just about the raw speed.
For most peoples uses, the i5 will probably be just fine. For those who want that extra bit of oomphh, the i7 will give very similar battery life to the i5 under light load, but you have the speed there when/if you should need it.
Happy to report my i7/8/256 will be showing up 1 day early, should be here any moment. (Not supposed to be here till tomorrow, FedEx even showed a 26th delivery date.) But I just checked tracking and it had my hometown and "On truck for shipment" woohoo...
Now i'll be able to compare it side by side with my wifes i5.
Now i'll be able to compare it side by side with my wifes i5.
That is the theory at least. My current machine is a 2011 i7 and the same discussions were going on two years ago - the consensus was that the i7 suffered from a lot more heat and significantly worse battery life than the i5 no matter what the activity.
It just showed up, I'm just getting a few things set up and I'll report back later.
I will say I am setting up & installing some programs and also about 50% into my Time Machine back up (which makes my rMBP hot) and the bottom of the laptop isn't hot. Just a little warm to the touch.
I will say I am setting up & installing some programs and also about 50% into my Time Machine back up (which makes my rMBP hot) and the bottom of the laptop isn't hot. Just a little warm to the touch.
