Apple's MagSafe Battery Pack has more capacity than it seems - here's why

Posted:
in iPhone edited August 5
The MagSafe Battery Pack appears to have a tiny capacity when examining its milliamp-hour rating, but that isn't the whole story. Here are the battery ratings and what they mean to users.

Apple's MagSafe Battery Pack has a higher capacity than the specs make it seem

Apple hasn't provided full specs for the MagSafe Battery Pack. Official photography shows a few numbers that give us insight into how much charging capacity it has.

At first glance, the numbers appear mildly disappointing, with a capacity one-third of the iPhone 12 Pro Max battery.

More important than milliamp-hours, though is power and voltage. The milliamp-hour rating is often used to define how much a battery can charge a device, but this only works as a comparable metric if both the battery and the charged device have an identical voltage.

• 1,460mAh
• 7.62V
• 11.13Wh

iPhone battery capacities

• iPhone 12 Pro Max - 3,687mAh
• iPhone 12 Pro - 2,815mAh
• iPhone 12 - 2,815mAh
• iPhone 12 mini - 2,227mAh
All iPhone 12 models use 3.81V batteries, so the MagSafe battery pack has a higher voltage potential, and therefore, a higher watt-hour rating than the iPhone it is charging. This means that the MagSafe Battery Pack can provide more power to an iPhone than its milliamp-hour rating implies.

Conversions

Understanding the effective power that the MagSafe Battery Pack can provide lies in a simple math equation.
Amps * Voltage = Power (in watts)
By utilizing this equation, we can figure out the effective milliamp-hours of the MagSafe Battery Pack for a given voltage. Or, more simply, we can figure out the Watt-hour ratings of each iPhone and use this as a direct comparison to the MagSafe rating.

In terms of milliamp-hours

If the MagSafe Battery Pack provides 1,460mAh at 7.62V, then the effective milliamp-hour rating at 3.81V would be 2,920mAh. This number is found by taking the battery's power rating and dividing it by the voltage of the iPhone.

At an effective 2,920mAh, if we assume 100% efficiency (which you can't in real life, but we'll get to that in a moment), the MagSafe Battery Pack would be able to fully charge an iPhone 12 or iPhone 12 Pro without much issue. However, users shouldn't expect a perfect transfer of power between the devices due to heat loss and poor efficiency.

Wireless charging is about 50% efficient, meaning half of the power is lost to heat or other losses. That being said, it's hard to figure out MagSafe charging efficiency. Apple's "special sauce" may lead to better efficiency than "basic" Qi.

There will be some discussion surrounding wireless charging efficiency later. But, with this initial look at effective milliamp-hours given the iPhone's voltage, the MagSafe Battery Pack doesn't seem so underpowered.

The MagSafe Battery Pack is the exact width of the iPhone 12 mini

In terms of Watt-hours

Mathematically, we can compare these ratings in many ways, but the amount of charge the battery provides will remain the same. While most battery packs use the milliamp-hour rating to represent capacity, Watt-hours would better explain the overall capacity without errors due to voltage differences.

The watt-hour value is a better indicator of overall device capacity because it takes voltage and amperage into account.
• MagSafe Battery Pack - 11.13Wh
• iPhone 12 Pro Max - 14.05Wh
• iPhone 12 Pro - 10.73Wh
• iPhone 12 - 10.73Wh
• iPhone 12 mini - 8.48Wh
Using this metric, we can see the MagSafe Battery Pack lies squarely between the iPhone 12 and iPhone 12 Pro Max in terms of total capacity. When we account for charging efficiency then the numbers aren't quite so impressive, but adequate given the battery pack's size. At 70% efficiency, the MagSafe Battery Pack would charge the iPhone 12 mini to about 90% capacity from zero.

Charging efficiency

There are a number of factors users should take into account when considering the battery capacity. While the numbers look good on paper for the MagSafe Battery Pack, once the ratings are properly examined, efficiency isn't 100%.

Apple acknowledges this by programming in some intelligence into the iPhone and MagSafe Battery Pack. To get the most out of using the MagSafe Battery Pack, Apple doesn't allow it to charge the iPhone at the same speed, given the conditions of the charge, including heat, and the charged iPhone's battery characteristics.

Apple's Intelligent charging features

• MagSafe Battery Pack will stop providing a charge if the iPhone reaches 90%
• If the iPhone becomes too hot, the MagSafe Battery Pack stops charging over 80%
• The MagSafe Battery Pack will ensure the iPhone reaches a full charge first before using connected power to charge itself
• The iPhone can charge the MagSafe Battery Pack through reverse charging if its internal battery is full and connected to power
Apple takes into account temperature considerations during any charging process. Introducing too much heat to a lithium-ion battery will cause it to degrade faster, so it isn't recommended to use wireless charging in overly hot environments.

Luckily, users do not need to consider charging efficiency or temperature when using their devices. Baked-in intelligence will handle all of this for them, so inefficient charging isn't taking place.

Charging efficiency via standard Qi is 50% as effective as a wired charger

Regardless of charging intelligence features, wireless charging is still inherently inefficient. Heat loss and magnetic loss will cause some of the MagSafe Battery Pack's power to dissipate at a rate faster than over a cable.

AppleInsider will test the charging efficiency of the MagSafe Battery Pack to determine exactly how much power it will provide in a stable environment. As previously mentioned, Qi charging is about 50% efficient, but we expect MagSafe wireless charging to be between 60% and 70% with Apple's battery intelligence.

The MagSafe platform has shown it uses proprietary technology and intelligence to overcome some of the issues with wireless charging. The MagSafe Battery Pack can provide 15W of power to the attached iPhone until it reaches one of the requirements mentioned above.

Is the MagSafe Battery Pack underpowered?

Our initial examination of specs and data here has shown that Apple's MagSafe Battery Pack isn't as weak an offering as initially feared. Its power rating shows it will have enough capacity to come close to doubling the battery life of an iPhone 12 mini during use.

Efficiency aside, we believe using the MagSafe Battery Pack will be a good experience for those who want a little more power throughout the day. Small battery packs like Apple's aren't meant to replace a dedicated power supply or daily charging routine but provide a few hours of extra device use when needed.

Apple's offering appears to be rather small and thin while providing nearly 100% of an iPhone's battery charge at 15W. We expect it to be sufficient for users seeking this type of battery pack.

Many were quick to compare the MagSafe Battery Pack to one made by Anker but didn't have the full story. The Anker battery pack has a 5,000mAh capacity but only charges at 7.5W and doesn't have the same charging intelligence features as Apple's battery.

AppleInsider will test the Apple MagSafe Battery Pack and compare it to its rivals once it becomes available. Customers can purchase the MagSafe Battery Pack for \$99 on Apple's website.

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Posts: 525member
I wasn’t really good in math and science in high school and 50 years later still confused by it all. But an excellent article regardless.
Posts: 3,251member
Amps is current. Watts is power. If you’re going to compare, you have make an equal comparison. Simple as that.

“ Wireless charging is about 50% efficient
This is what I find baffling about this product. The whole reason for having an auxiliary battery pack is because you’re running low on power, so why waste 50% of the reserve power you have on an inefficient charging process? Even if Apple improves significantly on Qi charging metrics, you’re still losing power.

Fundamentally, this is why I don’t care for wireless charging in general. It will always be slower and less efficient than wired charging. We should be looking to improve efficiency and power usage, not worsen it.
Posts: 12member
So they are using two 3.8v cells to get to 7.6 volts. My guess is they are using similar pouch cells as to what's in an older iPhone. Though  1460 mAh is pretty weak these days. I have cylindrical 18650 cells that are used out of scooter battery packs that I've tested @ 3000mAh. It could have been so much better if they had made it just a little bit thicker. As usual Apple cheaped out to maximize profit.
The iPhone 12 mini's battery is 2,227mAH, why didn't they just used those.
Posts: 65member
MplsP said:
Amps is current. Watts is power. If you’re going to compare, you have make an equal comparison. Simple as that.

“ Wireless charging is about 50% efficient
This is what I find baffling about this product. The whole reason for having an auxiliary battery pack is because you’re running low on power, so why waste 50% of the reserve power you have on an inefficient charging process? Even if Apple improves significantly on Qi charging metrics, you’re still losing power.

Fundamentally, this is why I don’t care for wireless charging in general. It will always be slower and less efficient than wired charging. We should be looking to improve efficiency and power usage, not worsen it.
Point taken but this charger isn’t supposed to do what a wired charger does. It’s not a daily driver, it’s for ppl who want something for on the go or just to have peace of mind for a night out. It’s perfect for those test cases.
Posts: 14member
I’m very tempted to get one, but I really wish they made one in black.

I’ll wait to official reviews come out to see how it looks. I’m afraid of it turning yellow.
Posts: 275member
ssalb said:

BLASPHEMY!

But seriously, recommending Apple's over the (little bit thicker) Anker seems like a really odd choice.  Even giving Apple's battery the benefit of all voltage/efficiency doubt, the Apple battery boils down to 7.8Wh delivered (1460mAh / 7.62V / 70% charge efficiency) vs Anker's 9.5Wh (5000mAh / 3.8V / 50% charge efficiency).  Oh, and Anker's is half the price.

Well, unless you're just deciding on thickness...
Posts: 2member
Hunter13 said:
I’m very tempted to get one, but I really wish they made one in black.

I’ll wait to official reviews come out to see how it looks. I’m afraid of it turning yellow.
Indeed, a black option or even an option in one of the new colors like Pacific Blue would be great. But I don't see Apple going that route. Black however along with the white option, would be a safe bet in my opinion. Still, I'm intrigued and am looking forward to the reviews on it.
Posts: 8,717member
50%!  Wireless charging is such a shit show.  I can't believe anyone is going for this crap.
Posts: 465member
The charging efficiency drops even further if the iPhone has a case on. And due to more heat, it will shorten the life of your un-swappable iPhone battery. It's totally meant for convenience which maybe useful for some people.
Posts: 3,251member
MplsP said:
Amps is current. Watts is power. If you’re going to compare, you have make an equal comparison. Simple as that.

“ Wireless charging is about 50% efficient
This is what I find baffling about this product. The whole reason for having an auxiliary battery pack is because you’re running low on power, so why waste 50% of the reserve power you have on an inefficient charging process? Even if Apple improves significantly on Qi charging metrics, you’re still losing power.

Fundamentally, this is why I don’t care for wireless charging in general. It will always be slower and less efficient than wired charging. We should be looking to improve efficiency and power usage, not worsen it.
Point taken but this charger isn’t supposed to do what a wired charger does. It’s not a daily driver, it’s for ppl who want something for on the go or just to have peace of mind for a night out. It’s perfect for those test cases.
Many people do use an auxiliary battery as their ‘daily driver,’ but more importantly, 50% efficiency means the battery is twice as big as it really needs to be.
Posts: 107member
That's why I've been ranting against mAh for years. It's meaningless information without giving the voltage.

Just use Wh, everybody. That's what it's for.

I hope AppleInsider will report it in the future.
Posts: 1,600member
Does it work with iPhones that have a protective case?
Posts: 10,260member
It feels to me that this whole thing is getting lost in the forest of trees...

I look forward to a hands-on review of how it works in real life under real world conditions.
What exactly is this thing good at?  And, what are its limitations?
edited July 15
Posts: 2,311member
foobar said:
That's why I've been ranting against mAh for years. It's meaningless information without giving the voltage.

Just use Wh, everybody. That's what it's for.

I hope AppleInsider will report it in the future.
Marketing. mAh is a bigger number than Wh. They could use amp hours (Ah) but they don't, again bigger numbers. Hilariously I've actually seen AI use kmAh...
Posts: 3,810member
I’m glad AppleInsider cleared up the confusion. Yeah, it was always just a little bit lazy to state only the current rating and assuming the voltage was always the same. But once the voltage wasn’t the same, the simplifying assumption no longer held up. These kinds of simplifying assumptions aren’t unusual in technology and sometimes leak over to nontechnical realms, even when they don’t apply, and none more so than use of terms (and their abbreviations) like kilo, mega, giga, cyber, and of course declaration of things as “digital.” Simplification can be a lossy process, especially with language.
Posts: 3,251member
elijahg said:
foobar said:
That's why I've been ranting against mAh for years. It's meaningless information without giving the voltage.

Just use Wh, everybody. That's what it's for.

I hope AppleInsider will report it in the future.
Marketing. mAh is a bigger number than Wh. They could use amp hours (Ah) but they don't, again bigger numbers. Hilariously I've actually seen AI use kmAh...
That’s why you use mWh, or, if you want your battery to seem really big, microWh!
Posts: 2,311member
MplsP said:
elijahg said:
foobar said:
That's why I've been ranting against mAh for years. It's meaningless information without giving the voltage.

Just use Wh, everybody. That's what it's for.

I hope AppleInsider will report it in the future.
Marketing. mAh is a bigger number than Wh. They could use amp hours (Ah) but they don't, again bigger numbers. Hilariously I've actually seen AI use kmAh...
That’s why you use mWh, or, if you want your battery to seem really big, microWh!
Keep that quiet or that’ll be next!
Posts: 11,565member
MplsP said:

Fundamentally, this is why I don’t care for wireless charging in general. It will always be slower and less efficient than wired charging. We should be looking to improve efficiency and power usage, not worsen it.
Wireless charging is about convenience, not efficiency. When I get into the car and plop my phone down for a short trip, or if it’s bedtime and it will be sitting all nite, that convenience is more important to me than efficiency.

Yes, losing wasting power is unfortunate. But people make this same decision every day -- ice, AC, TV on in background, etc…Not needed, but often enjoyed. If I choose to indulge with this I don’t see how it’s any different.
Posts: 909member
But who carries their phone around (outside at least) without a case?  These devices are way too expensive to risk dropping onto pavement without protection.

I suppose if you buy AppleCare+ and you’re rich enough to be able to buy a new phone on the spot or don’t care about the excess, then you mightn’t care.  Booking service at Apple can take a week or two sometimes as well, so there’s a huge inconvenience factor to deal with regardless.  My phone just took a hard drop onto tiling in the bathroom and without a good quality case it would’ve broken.

I’m pretty sure Apple only bothers with these batteries and many of their other accessories because they’re able to manufacture them for peanuts and sell them for huge markups.
edited July 16