iPhone 4 Gear Review: The Etón Mobius Rechargeable Battery Case with Solar Panel

Can you picture yourself out camping for a week? Your car is parked in a lot miles away, and you have been hiking for days. You’ve got everything you need in your backpack, and you’ve been eating those freeze-dried dinners that they sell at REI. Civilization is nowhere near, and you are looking forward to having a shower … in a few more days. You want to stay in touch with your family, but there are no chargers built into the side of the trees you’ve been passing, and your iPhone died yesterday. What do you do?

Okay, I am having trouble picturing myself in that situation, so let’s try a different scenario. =P

Let’s say that you live in one of the states that is prone to hurricanes, earthquakes or tornadoes. Disaster struck a few days ago, and power still hasn’t been restored. You want to call your out-of-state family members and let them know that you are okay, because by now you are sure they must be frantic. It doesn’t help that the last thing you tweeted, which also posted to your  Facebook wall, was something along the lines of “OMG! Tornadoes do sound just like a freight train as they pass by!”, followed with “I just saw a car sail down the street!” The problem is that your phone didn’t have a full charge when disaster struck, and you were too busy hiding and then digging out and helping the neighbors to even check your phone … which is now dead as a doornail. What do you do?

Well, if you planned ahead, you’d just snap your phone into the Etón Mobius Solar Rechargeable Battery Case. If you’d had time to set it up beforehand, you could have charged it via the included microUSB cable, and it would be ready to go once snapped onto your iPhone. If you hadn’t had a chance to charge it fully, or if you’d used all of its additional battery power already, the solar panel on the charging case’s rear would be all that you needed to convert  the sun’s energy into iPhone battery power. That’s the premise, anyway. To see how the Mobius performed during my testing, read on!

The package contains the charging case, a microUSB cable, a user manual, a single page on how to insert or remove the iPhone from the case, and a USA & Canada limited warranty.

The charging case is composed of shiny black plastic, and it measures 5.1″ long x 2.44” wide x 0.875” thick. Without the iPhone inserted, it weighs 3.4 ounces; add that to the iPhone’s 4.8 ounces, and you get a package weighing in at 8.2 ounces. That’s a heavier and bulkier handful than what you’re used to holding, no matter how you try to spin it. But if the case does what you need it to, then having what amounts to a chubby and hunchbacked iPhone may be easier to accept. At first glance, the interior of the case appears to be  lined in a thin layer of neoprene, but alas — it is just textured black plastic.

The solar panel itself measures approximately 4.1″ long and it sticks up about 0.5″ from the lower level on the back of the case. The solar panel is shiny plastic, but its four sides are composed of black plastic that’s been covered with non-slip paint.


There are a series of switches and indicator lights on the bottom rear of the case; let’s start with the very bottom of the case. The two larger ovals are the microphone and speaker ports, and they do work nicely to keep the phone’s sounds and the user’s voice from being muffled. The round button in the center is actually an LED that blinks orange when the exterior battery is charging in the sunlight; it will also come on if you are charging the battery pack via microUSB in a well-lit room. It is definitely light-activated, though, as it will stop flashing if you cover the solar charger with your hand.

On the upper level, going from the left to right, there is an on/off switch so that you can conserve the external battery pack’s reserved charge when it’s not needed; there is no point in trying to force-feed a charge to an already full iPhone battery, right? Next is a long narrow button that when pressed shows you the external battery’s power level; four glowing means that it is full, and the less LEDs showing means the less charge you have in reserve. The LEDs on either end will glow back and forth when charging via microUSB, which just so happens to be the port on the far right.


You can tell just by looking at it that the Mobius is going to make the iPhone look huge … can’t you?


To insert the iPhone, you slide down the bottom portion of the case and then you insert the iPhone left side first and then slide in the right. The case is closed when you slide the bottom — the portion which contains the charging apparatus — into the iPhone’s charging port. This is probably one of the more clever methods I have seen to close a slider case, and it does work well.


The case is held on the iPhone via friction, and there is understandably a very tight fit. Putting the iPhone into the case is easy enough, but getting it out is a whole different issue. I’ll talk more about that in a bit. The cutout on the side is wide enough to create easy access to the mute switch and the volume buttons; it works on both the AT&T iPhone 4 and the AT&T iPhone 4S, and it should work with other carriers’ iPhone versions as well.

There’s a generous cutout around the rear camera lens and LED flash, and a nearly invisible “mobius” is embossed in the shiny black plastic.


It doesn’t take much natural light to start the solar panel charging; lying on my dining room table at 5pm in October, I can still see that there is a benefit being received — although I have found that the solar cells work even more efficiently when the phone (or case alone) is lying in brighter light. Through my  testing, I found that I could completely untether myself from any and all electrical outlets by keeping the Mobius charged.


If you vacation (or live) off the grid, and you need to keep your iPhone charged, the Etón Mobius would be a great way to manage your power.

Here is the downside, though. The Mobius is big, there is no way around it. I would have probably preferred it if the Mobius had been more of a holster style with an open top — something I could have slid the phone into when a charge was needed, and yes — I know that defeats the purpose of the Mobius being a case. With how hard it is to remove the iPhone from the shell, your best bet — if you need a case like this — is to insert the iPhone and leave it in there. But when you do need to get your iPhone out, pressing a finger into the camera hole while pulling up on the left side of the phone is about the easiest way to coax the iPhone out.

You remember how in the early days of solar mobile accessories, they never seemed to charge fast enough or strongly enough to be much use? The good news is that those days are gone. The Etón Mobius Rechargeable Battery Case with Solar Panel easily does what is expected, and it does it without a lot of thought on the user’s end. Flip your phone over when you aren’t using it, and the solar panel will go to work. Use your phone in a well-lit room, and the solar panel is working. Turn the battery off to stop delivery to your iPhone and conserve its stored charge, and press the button to see how much power you have in reserve; it couldn’t be more simple.This 1800 mAh battery pack is more than sufficient to keep the iPhone’s battery topped off throughout the day, or recharged if you’ve let the battery run down. The tradeoff for all this available green power is that your iPhone will be a bit of a brick; only you can decide if that’s a deal-breaker or not.

The Eton Mobius Rechargeable Battery Case w/ Solar Panel for iPhone 4 [affiliate link] is available from Amazon.

MSRP: $80

What I Like: Generous 1800 mAh battery pack; on/off switch so that you can conserve the battery’s reserved power; four LEDs indicate how much battery power remains;

What Needs Improvement: There’s no way around the fact that this charging case makes the iPhone resemble a brick; Case is very hard to remove, and I don’t recommend doing it frequently

Want More? Follow Us Here!

Please be aware that when appropriate, we sometimes place affiliate links in our posts. If you make any purchases through those affiliate links, you will be supporting Gear Diary with a small percentage of your sale. As an Amazon Associate, we earn from qualifying purchases. Thank you for your support!

For more info on Reviews & Disclosure, click here.

About the Author

Judie Lipsett Stanford
I've had a fascination with all types of gadgets and gizmos since I was a child, beginning with the toy robot that my grandmother gave my brother - which I promptly "relieved him of" in 1973. I'm a self-professed gadget magpie. I can't tell you how everything works, but I'm known world-wide for using a product until I have a full understanding of what it does, what its limitations are, and if it excels in any given area — or not.