Mugen Power Battery Case for Lumia 920 review

Mugen Power Battery Case for Nokia Lumia 920: Hands-On Review

A few months back I reviewed the Brando Power Jacket case for the Nokia Lumia 920. A case with a built-in battery, it could potentially double the battery life of the Lumia 920 – a dream for gamers. But the Brando case didn’t perform all that well as a charger, limiting its usefulness.

Enter Mugen Power, makers of many external batteries and cases. At long last, Mugen now offers an extended battery case for the Nokia’s original flagship Windows Phone 8 handset. The Mugen Power Battery Case for Lumia 920 comes in black or white, as well as two different battery capacities: 3000 mAh and 4700 mAh. The 4700mAh model offers 2.35x extra power on top of the 920’s built in battery. I’ve spent the last few weeks using that version as my case in order to bring you this detailed review.

Mighty Mugen Power Ranges

Mugen Power Battery Case for Lumia 920 review

The Lumia 920’s built in, non-replaceable battery holds 2000 mAh of power. The Mugen Battery Case comes in both 3000 mAh and 4700 mAh sizes. The price difference between the two is only ten dollars, making the choice between models come down mostly to size and weight. The larger capacity case is a few millimeters thicker than the smaller one, and presumably heavier too.

Even the 3000 mAh case will provide more power than the Brando Power Jacket, which has a capacity of 2200 mAh. At 3000 mAh, you’re looking at 150 percent extra power on top of the 920’s internal battery – more than doubling the available power, in other words. The 4700 mAh case I’ve been using exceeds the phone’s standard battery by 235 percent, basically tripling the power it has to work with.

How well does one of these cases extend the 920’s battery life in practical terms? An unenhanced Lumia 920 will likely get 2-3 hours of playtime from a graphically intensive game. After that, you’d better plug in or you’re going to miss some calls.

With Mugen’s 4700 mAh case, I played Temple Run 2 for five hours (yar, a tad boring) without fully draining the case. The phone itself showed some battery drain; these cases can’t eliminate the fact that 920s sometimes use power faster than they can charge. But the case certainly helps!

Retraction action

Mugen Power Battery Case for Lumia 920 review

The Mugen Battery Case connects to the Lumia 920 in a most unusual way. Unlike the Brando Power Jacket, this case doesn’t cover the bottom of the 920 where the phone’s micro-USB port calls its home. The bottom of the phone remains largely exposed while inside the case. The bottom-left side of the case houses a retractable micro-USB plug that provides power to the phone.

A hole at the bottom of the case holds the plug snugly when not in use. Pull the plug out of the hole and you’ll find a thin, coiled wire about three centimeters in length. The wire is built into both the micro-USB plug and the inside of the case itself. It allows just more than enough room to connect the case to the phone’s power jack.

After plugging the Mugen Battery Case’s male connector into the power jack, the case automatically starts charging the phone. No pressing a button to switch to charging mode here; connecting the case while it holds a charge is just like plugging in a charger. One won't get into situations where the case is charging itself but not the phone (both can charge simultaneously), unlike the Brando Power Jacket which often stopped charging the phone.

Mugen Power Battery Case for Lumia 920 review

However, the retractable plug betrays some significant design flaws. The cord itself is quite thin and can’t be replaced if it breaks on either end. Cut or tug too hard on it and your hundred dollar case drops to a value of zero. The charging plug itself is too fragile as well. It sticks out from the phone, completely unguarded during use. If the plug is bumped too hard or the phone gets dropped and lands on it, the plug will bend or break - possibly even damaging the phone's micro-USB port in the process.

That fragility of charging plug and cable means you shouldn't leave the case charging your phone all the time, as nice as the constant power supply is. When you’re walking around with the phone in-hand or in-pocket, you’ll probably feel a lot safer with the plug retracted inside of the case. Not a tradeoff we should have to make. At least Mugen Power offers a one year warranty, but those don’t usually cover damage from dropping and other accidents.

Big is beautiful

Mugen Power Battery Case for Lumia 920 review

Power connector issues aside, the Mugen Battery Case is mostly a good case. It adds a significant depth to the phone and a noticeable amount of weight. The extra size doesn’t make the phone too hard to pocket or anything, though it’s certainly hard to miss when looking at the phone.

The extra weight could be a concern for some users, but not this guy. As a gamer, I’m used to holding controllers that weigh just as much as a 920 with the 4700 mAh case on. I find it perfectly comfortable; it doesn’t fatigue me a bit.

The Battery Case has cut-outs for all of the buttons along the right-side of the phone: volume, power, and camera. A little behind the volume buttons, you’ll find the micro-USB port used to charge the case itself. A tiny red light next to the port comes to life when the case is charging.

On the rear of the case, a conical cutout allows the camera and flash to work unimpeded. Four LEDs and a button occupy the bottom rear of the case, just below the Mugen Power logo. Pressing the button will light up the LEDs and indicate the case’s remaining charge. I like that the lights only come on when checked instead of wasting power on them all the time.

Not the full wraparound

Mugen Power Battery Case for Lumia 920 review

If the Mugen Battery Case has one more flaw, it’s how much of the phone it actually covers. The case does not cover the top or bottom of the phone, although it does extend about a millimeter beyond the phone’s borders on those sides. This provides some minimal protection to the top and bottom areas, but not much. More egregiously, the case does not cover the front of the phone and the screen at all. The 920’s most fragile side - the one that most needs protection – is the only side that gets none.

Overall Impression

The lack of protection to the front of the phone belies the Mugen Power Battery Case’s strange design ethic. The number one reason anybody buys a case is to protect their phone. This case offers more protection than no case at all, but not to the all-important screen. I dropped my phone and got several new scratches that wouldn’t have happened had I kept using the Brando Power Jacket. The fragility of this case’s charging cable and plug is also worrying, especially given the high cost of the case.

On the other hand, the Mugen Power Battery Case for Nokia Lumia 920 is one hell of an external battery in either power capacity. I absolutely adore how much extra playtime and usage I get from my 920 with this thing attached. When I’m not gaming, I can go an extra day or two without plugging into a wall. And when I do game, I can play for as long as I want without being tethered to a charger.

For me, the benefits of the case’s voluminous power supply just outweigh the protection I give up from other cases. But I might feel differently if my Lumia 920 was at the beginning of its life instead of the tail end. If you’re looking to extend your 920’s day-to-day gaming life and you don’t have trouble keeping your phones free of bruises, give Mugen Power’s solution a look.

  • Mugen Power Battery Case for Nokia Lumia 920 – 3000 mAh – $89.99
  • Mugen Power Battery Case for Nokia Lumia 920 – 4700 mAh – $99.50 – Mugen Power Store Link (all varieties)

Reader comments

Mugen Power Battery Case for Nokia Lumia 920: Hands-On Review


With the USB out like that it gives it chance to snap the USB port in the inside when it drops. Happened to my Samsung Focus while I was charging it and dropped it.

Broke one on L710) now my L928 always charging on the floor))

But that thing looks ugly. Remember ppl complaining about 920s weight now this one is a huge brick)

I have strange problem with my device's battery. Problem is that it takes almost 2 hours to reach 99% once it reaches 99, it takes another 1 hour or more for making it 100% !! Is there anything wrong ? Sorry for my bad English :)

I had similar charging issues and found that it was the actual charger itself.. The cords ware out and they need to be replaced from time to time.. Another thing is if you're using a no name aftermarket charger then they work significantly worse than the Nokia branded chargers that the phone came with.. Unless you're using a Belkin charger, which I'm sure is the same as the Nokia chargers.. I'm pretty sure Belkin makes these chargers for Nokia.. Anyways, check your charger❕❕

Hey bro, i use original Nokia accessories(charger) which came with along with the device.

Function over form in this case.. But, you're right.. It's so ugly it's almost funny looking.. Lol❕

For me....if i play game while charging,then the phone gets so hot....and the battery starts draining faster than charging.....

This looks insanely horrible. You are not going to carry this thing around, and if you need to charge your phone on the go, I'm sure you'd rather get an external battery like Anker.

External batteries are bad for gaming, though. I think having the battery firmly connected to the phone is the appeal of battery cases.

Thanx... But don't u think 1800 mAh battery capacity little on lower side??!! Because 820's battery capacity is 1650mAh, and mugen power offers only 150mAh higher with a lot high price..... Is it worth to give a try?? What u think??
and 3600mAh comes with bulky back cover and in that price i can buy a external battery backup or a phone.
location: India.

I personally would buy whatever extended battery options are available for my phone of choice. I want to be able to game for as long as I can, and I'm willing to spend a bit for the privilege.

I agree that the 1800 mAh battery is not a significant upgrade, but every little bit of power helps. Especially if you've had the 820 for a while, your phone's battery is already losing a bit of its capacity. So a new 1800 mAh battery would seem like a bigger upgrade over a somewhat used 1650 one.

If you want more power but not specifically for gaming, an external battery might still be the best value. They're not good for charging while playing a game (unless you can set the phone down on a flat surface while playing) but still a nice way to charge the phone when it's not in use and you're not near an outlet.

All depends on your needs and preferences.

With that size I suppose I can spend the $100 to buy a Lumia 520 and carry that with me as spare. Shouldn't be any heavier than this 'thing'.

There's a lot of things they "could have" done with this case. The whole thing is a failure. I've seen better. This was simply a cheap build to see if there's interest. Than if there is they'll come out with the "air" version.

Also how does this effect camera, with my case, i have to remove it before using camera to avoid all the flash echo from the case

Gross. I remember the one for the iPhone 3GS before the "Air" version came out... This one is worse than that. Its the thickness of three 920s... And I've held a 920 before... There bulky enough as it is. No thanks. 50,000mAh Portable charger for $24 on eBay thats the same size as the phone is much more predictable and will keep your phone charged for a few weeks lmao.

LOL where are they getting those numbers from? 50,000 mAh would be A LOT larger than that thing. Look at the pictures in that same item, the product itself lists itself as 20,000 mAh.

Looked it up. The 50k one is no bigger than the galaxy s4. About the same size. Obviously a little thicker. Batteries for your phone have alot of plastic holding them together. If you create a battery with more cell/plastic ratio you can fit more into a space like these packs. Believe that's plenty of space for 50k mah

Why can't they just make a version with Qi charger?! If they can reach efficiency of 70% (most pessimistic factor value, it will be more effective indeed) due to wireless charging, that'll be around 4.7*0.7=3.3 Ah which still comes one and a half times more than built in the 920! That's totally enough for full day of intensive use, who needs more?

The phone will not receive all the energy in the battery so a 3000mAh battery isn't really 1.5 times the internal battery. This is because a USB port uses 5V whereas the battery is nominally at 3.7V. There is a DC-DC converter in the battery to step up the voltage to 5V and another DC-DC converter in the phone to step the voltage back down. At each conversion energy is lost. Anker claims 70% of the bettery energy makes it into the phone battery and that their newer battery systems have improved that somewhat. If this battery case is about as efficient as the Anker 10,000mAh battery then only expect about 2100mAh equivalent for the 3000mAh model.

Wow, who in their right mind approved that design? Like which guy said "I know, I got it!!" More importantly who was the suit that agreed with that guy to actually move things forward? Could be the ugliest accessory ever, for any phone.

That's just.... horrid.  Who thought that was a good idea?  If it was just bulky and nasty-coloured, then maybe it would have some merit, but that charging cable sticking out the bottom?  Did they leave the design of this up to a 12-year-old?  An abomination.

There is no design reason they cant do a similar one to apple, plugs into usb directly, and is less than half the fatness of this thing

One huuugge fail cover.


Yet, had it been with wireless charging, then... a logic choice and actually worth peoples time.


But seriously. Who ever buys this, deserves the ridicule.

I'm glad it doesn't cover the speakers or microphone. I wouldn't say that's a flaw, more of am advantage.

Not covering them is good, but you can accomplish the same thing with cutouts for those items. That's what other cases do.

Looks bad... the USB connection is just waiting to be damaged. This slapped on slab thingy should at least be wireless. And thinner... much much thinner...

I think Nokia should make a phone with an option to have it charge with solar power, have an option to turn on/off solar charge, so when your outside your battery could charge abit.. Just a suggestion..

It's not a beautiful case, but I don't think the average passer-by looks all that closely at whatever phone someone is playing with.