Charging // USB vs AC

GoldMan

macrumors member
Original poster
May 4, 2009
72
0
Europe
Hi. Yes i know its faster charging with the AC, but which one is good for the battery? USB Charging or normal AC charging?


Me: I've noticed that i sometimes get 1-2 hours more battery life when i full charge with the AC :confused:
 

takeshi74

macrumors 601
Feb 9, 2011
4,972
68
Yes i know its faster charging with the AC
Not necessarily. Depends on the specs of the charger. If you use a 500mA AC charger it's going to be the same.

It's the same.
^ This. Generally speaking, slow charging can be beneficial if it minimizes heat but I have yet to see anything that indicates that using the stock AC charger for your iPhone would cause a significant negative impact.

Me: I've noticed that i sometimes get 1-2 hours more battery life when i full charge with the AC :confused:
You might want to read up on causal versus coincidental. What you're seeing may be the latter but it's impossible to say based on what you've provided. If you really want to compare charge then you shouldn't rely solely on the battery meter as it's not all that accurate IIRC.
 
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BiggAW

macrumors 68030
Jun 19, 2010
2,542
171
Connecticut
I actually think devices hold the charge better when charged with the high-current chargers, but I have nothing to prove it. It definitely doesn't have any long-term effect.
 

AllieNeko

macrumors 65816
Sep 25, 2003
1,004
57
I actually think devices hold the charge better when charged with the high-current chargers, but I have nothing to prove it. It definitely doesn't have any long-term effect.
You're definitely wrong. Charging batteries more slowly means less heat means longer lifespan. That's why the final few percent of the charge happen so slowly. Most of the charge can run faster and then the last few percent can be trickle charged.

And I DO have the proof if you want it, to show you higher current charging kills batteries. Newer lithium chemistry is so intelligently charged that it makes little difference I'm sure, but look at the damage "15 minute" chargers do to NiMH batteries....
 

BiggAW

macrumors 68030
Jun 19, 2010
2,542
171
Connecticut
You're definitely wrong. Charging batteries more slowly means less heat means longer lifespan. That's why the final few percent of the charge happen so slowly. Most of the charge can run faster and then the last few percent can be trickle charged.

And I DO have the proof if you want it, to show you higher current charging kills batteries. Newer lithium chemistry is so intelligently charged that it makes little difference I'm sure, but look at the damage "15 minute" chargers do to NiMH batteries....
Again, I have nothing to prove it, except anecdotal evidence, and it may just be that the effect of newer battery technology is much larger than the degradation due to fast charging, but my now several year old 15 minute Rayovacs are absolutely the best rechargeables I have, with the possible exception of my brand new pre-charged ones (I got pre-charged so they wouldn't drain themselves out in a month after recharging like many do).
 

AllieNeko

macrumors 65816
Sep 25, 2003
1,004
57
Again, I have nothing to prove it, except anecdotal evidence, and it may just be that the effect of newer battery technology is much larger than the degradation due to fast charging, but my now several year old 15 minute Rayovacs are absolutely the best rechargeables I have, with the possible exception of my brand new pre-charged ones (I got pre-charged so they wouldn't drain themselves out in a month after recharging like many do).
Absolutely true on that, newer batteries are MUCH better tech. Batteries sold today charged on "15 minute" chargers will still perform much better than NiMH batteries from a decade ago. Likewise with lithium batteries, they have got the chemistry for lithium batteries much more stable. My 14 month old MacBook Pro has 132 cycles and is still capable of 92% of it's design capacity. I'm careful to almost never let it fully die, and to avoid leaving it in my hot car, but other than that, normal use. DANG IMPRESSIVE. 132 cycles was the point of around 70% or so of design capacity in batteries made 5 years ago. Apple claims 1000 cycles to 80% of design capacity for MacBook Pro/MacBook Air/iPad and 400 cycles to 80% for iPhone/iPod. I'll believe that when I see it. But a few years ago 300 cycles to 50% was the industry standard for all lithium batteries.
 

BiggAW

macrumors 68030
Jun 19, 2010
2,542
171
Connecticut
Absolutely true on that, newer batteries are MUCH better tech. Batteries sold today charged on "15 minute" chargers will still perform much better than NiMH batteries from a decade ago. Likewise with lithium batteries, they have got the chemistry for lithium batteries much more stable. My 14 month old MacBook Pro has 132 cycles and is still capable of 92% of it's design capacity. I'm careful to almost never let it fully die, and to avoid leaving it in my hot car, but other than that, normal use. DANG IMPRESSIVE. 132 cycles was the point of around 70% or so of design capacity in batteries made 5 years ago. Apple claims 1000 cycles to 80% of design capacity for MacBook Pro/MacBook Air/iPad and 400 cycles to 80% for iPhone/iPod. I'll believe that when I see it. But a few years ago 300 cycles to 50% was the industry standard for all lithium batteries.
Quite true. Even MB to MBP transition for me the battery tech got a lot better, and those machines were only 4 years apart.
 
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