If you're still rocking a Lumia 950 XL (god bless you) but aren't too pleased with how long your battery lasts, we might have a solution. Mugen Power, an accessory maker, happens to sell a huge internal 9,300mAh battery for the 950 XL that costs $100 (though it's currently on sale). But be warned: It makes your Lumia 950 XL look really silly.
There's a reason smartphones don't come with super large batteries, and that's because they make phone super large. A 4,000mAh battery is about as big as you can go before things start getting chunky. So, a 9,300mAh battery is pretty big, and as you can tell by our images, it makes your Lumia 950 XL pretty ... fat. This is an internal battery, meaning there are no external power packs.
Aesthetics
The battery is so big, Mugen Power provides its own custom shell for the 950 XL that you have to use. The 9,300mAh battery doesn't fit inside a normal shell for the 950 XL. With the Mugen Power shell on, your Lumia 950 XL will be a whopping 0.66 inches thick.
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On the plus side, that raw thickness gives you an extended amount of battery. Instead of lasting a day on the normal 3,500mAh battery, you can get up to three whole days off a single charge.
Battery life
I've been using the Mugen Power battery for around two weeks. Most of the time the battery lasts three days, dropping under 10 percent on the third day. Sometimes, however, I just can't get that mileage. I don't know if it's how I'm using the phone, a bug with Windows 10 Mobile, or an issue with my battery. With the 9,300mAh battery, I'll sometimes get two days, or in a worst case scenario, a day and a half. That's still an improvement, but not by much. On average, I get two to three days of battery on a single charge.
Charging the Mugen Power battery is also slightly odd. I've noticed the device will charge to about 70 percent pretty quickly, but from there it'll take two or more hours to charge from 70 percent to 100 percent. I also assume Windows 10 Mobile itself isn't all that accustomed to measuring battery life from a 9,300mAh cell, which might be causing its own issues with the percentage indicator.
The Mugen Power shell doesn't creak, unlike the stock shells that ship with the device. I have noticed that the buttons feel clickier too, although that might just be unique to my shell.
In conclusion ...
Overall, I really like the Mugen Power battery shell. It gives you great battery life (most of the time), and although it is incredibly thick, it doesn't feel too bad when in hand or in your pocket. You may get some funny looks in the street, but what does that matter when your phone is on a three-day streak with no charger in sight?
There's also a version of the Mugen Power battery for the smaller Lumia 950 too. The battery is also smaller, being 6200mAh instead of 9300mAh, but that's because the size of the 950 is smaller in general, and as a result doesn't have enough room to fit a 9300mAh. While I haven't personally tested the 6200mAh battery, Mugen Power says their battery should double your Lumia 950 battery life. Check it out here.
The one thing that may put people off is the price. This battery and shell usually cost $99.99, which isn't cheap by any stretch of the imagination. You can get them for $79.99 right now on Amazon, however. If you really want longer lasting battery, the cost is worth it. If you're OK with getting through a day on a single charge, I'd probably steer clear.
