40w Dynamic Power Adapter vs. 20w Power Adapter

[mwhite]

I recently bought an iPhone 17 and along with it the 40w Dynamic Power Adapter. However, I'm concerned that using the fast charging all the time might be bad for my battery. Because of that, I also bought a 20w power adapter yesterday. I always charge my phone overnight while I sleep, and I figure the 20w would be better since I don't need fast charging overnight, and I would only use the 40w adapter in situations when I'm low on power and need a faster charge. Or, maybe I don't need to worry about using the 40w adapter all the time? Should I return the 20w adapter?

My other concern is my phone staying plugged in to any power adapter once it's reached full charge. I have experimented with different charge limits, and it seems I can get away with a charge limit of 80% since I am not constantly using my phone. With the 40w, it will reach that limit quickly, and then my phone will stay connected until I wake up. It will take longer with the 20w, but again, stay connected until I wake up. Optimized battery charging isn't available unless you set your charge limit to 100%, so, do I have cause for concern? I would like to preserve my battery health and life as long as possible.

Thanks in advance for any wisdom given!

 

[snipr125]

Personally I would keep the 20W charger as it has the right balance of speed and heat when charging, and set your charging to 100% with optimised charging. Other members will probably say it makes no difference and to just use your phone normally.

 

[mwhite]

Personally I would keep the 20W charger as it has the right balance of speed and heat when charging, and set your charging to 100% with optimised charging. Other members will probably say it makes no difference and to just use your phone normally.

Well, I can’t return the 40w, I’ve been using it for a month, but I never had any intention of returning it. I don’t want to set my charging to 100%, because everything I’ve read says it wears out your battery faster. I’ll have to decide if I want to return the 20w or not, I guess.

 

[Bichon]

For my iPhone 17 Pro, I use the 20w charger, charge overnight with the limit set to 80%. I've never come close to running out of juice, this phone lasts longer with 80% SOC than my 14 Pro did with 100%.

 

[BigMcGuire]

I recently bought an iPhone 17 and along with it the 40w Dynamic Power Adapter. However, I'm concerned that using the fast charging all the time might be bad for my battery. Because of that, I also bought a 20w power adapter yesterday. I always charge my phone overnight while I sleep, and I figure the 20w would be better since I don't need fast charging overnight, and I would only use the 40w adapter in situations when I'm low on power and need a faster charge. Or, maybe I don't need to worry about using the 40w adapter all the time? Should I return the 20w adapter?

My other concern is my phone staying plugged in to any power adapter once it's reached full charge. I have experimented with different charge limits, and it seems I can get away with a charge limit of 80% since I am not constantly using my phone. With the 40w, it will reach that limit quickly, and then my phone will stay connected until I wake up. It will take longer with the 20w, but again, stay connected until I wake up. Optimized battery charging isn't available unless you set your charge limit to 100%, so, do I have cause for concern? I would like to preserve my battery health and life as long as possible.

Thanks in advance for any wisdom given!

Your phone handles its battery intelligently. The fastest rate of charge is usually between 0% and 70%. After 70% the phone will charge less rapidly to protect the battery. You'll notice it will only draw a few watts as it's charging from 90% to 100% (even if plugged into a 200w charger). Also, this is why it can take just as long to go from 0-80% to go from 80% to 100%. Your phone will protect your battery and only ask for the charging rate it wants and thinks is safe.

I set my 17 Pro Max to 80% max charge (and I did this with my 15 Pro Max the 2 years I had it). This helps your battery longevity especially if you leave your phone plugged in all night (like I do). In this case, no difference between 20w or 40w.

BEST thing to help your battery health? Keep it out of the sun, don't leave it in your car, try not to overheat it. This will have the biggest impact on your health. Charging slowly from say, 10% to 80% vs charging at full 40w will not have a ton of impact over the life of your phone. Keeping the phone cool, setting max charge to 80% (especially if you leave it plugged in all night) - will help.

Want to care for your battery? Check out: https://www.batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries/ - depth of discharge has an impact (not going below 20%, keeping max charge at 80%).

But also keep in mind, it only costs $89? for Apple to replace your battery. This is supposed to be something that helps your life, not an inconvenience. If you do the 80% max charge, plug in every night, don't leave your phone in the sun - you should get years of use out of your battery before even having to think about a battery replacement.

My 15 Pro Max was at 99% health after 2 years doing this.

 

[mwhite]

Your phone handles its battery intelligently. The fastest rate of charge is usually between 0% and 70%. After 70% the phone will charge less rapidly to protect the battery. You'll notice it will only draw a few watts as it's charging from 90% to 100% (even if plugged into a 200w charger). Also, this is why it can take just as long to go from 0-80% to go from 80% to 100%. Your phone will protect your battery and only ask for the charging rate it wants and thinks is safe.

I set my 17 Pro Max to 80% max charge (and I did this with my 15 Pro Max the 2 years I had it). This helps your battery longevity especially if you leave your phone plugged in all night (like I do). In this case, no difference between 20w or 40w.

BEST thing to help your battery health? Keep it out of the sun, don't leave it in your car, try not to overheat it. This will have the biggest impact on your health. Charging slowly from say, 10% to 80% vs charging at full 40w will not have a ton of impact over the life of your phone. Keeping the phone cool, setting max charge to 80% (especially if you leave it plugged in all night) - will help.

Want to care for your battery? Check out: https://www.batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries/ - depth of discharge has an impact (not going below 20%, keeping max charge at 80%).

But also keep in mind, it only costs $89? for Apple to replace your battery. This is supposed to be something that helps your life, not an inconvenience. If you do the 80% max charge, plug in every night, don't leave your phone in the sun - you should get years of use out of your battery before even having to think about a battery replacement.

My 15 Pro Max was at 99% health after 2 years doing this.

One thing. I have learned that apparently, according to Apple, when your phone is left plugged in all night it doesn’t use any battery power at all. Instead, it draws power from the electrical outlet, even after charging is complete.

 

[BigMcGuire]

One thing. I have learned that apparently, according to Apple, when your phone is left plugged in all night it doesn’t use any battery power at all. Instead, it draws power from the electrical outlet, even after charging is complete.

Yeah, one thing I have really loved about extending the life of my battery - you can bypass the battery and just run off of wall power - saving a lot of charge cycles. Great for someone like me who works at a desk. I can use 1 cycle in a week if I don't get out and about as much as I should. 😛