TechnologyTell Review: LinearFlux LithiumCard Pro battery

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The portable external battery pack market is huge and saturated, which can make choice pretty hard. Thankfully, the selection dwindles down quite a bit once you focus on important aspects and stick with it. But sometimes you’ll find a device that impresses all over, even if it may not truly fit your criteria. So then what do you do?

You buy it anyway and add it as part of your gear, silly.


Sticking with the whole wallet-sized feel, the LithiumCard Pro maintains a profile that is very close to the length and width of a standard credit card. If you set one (card) on top, the edges of the LithiumCard Pro stick out 2-3mm on each side. It’s not a lot, ensuring this battery is still very compact. While the overall thickness – about 9 quarters worth – prevents it from being wallet-friendly, the LithiumCard Pro is definitely pocket-ready.

LinearFlux LithiumCard Pro battery box

Both the battery and its packaging is eye-catching.

Although slightly bigger and twice the thickness of the original LithiumCard, the Pro version maintains similar shape and style. It’s also a lot lighter than one might expect it to be. The top and bottom feature brushed metal plates that feel embedded in the hard plastic body. Peeking through the engravings is the power LED indicator light, which looks artsy when it’s not on or flashing.

The construction quality of the Pro is better than the original LithiumCard. And that has been able to take quite the punishment over the past year, yet it keeps on going with the same performance as ever. Sure, maybe neither LinearFlux batteries won’t look pretty after being put through the ringer of daily use and life, but know that both will last and work reliably.

Anything other than the standard 4-LED power indicator lighting method, used by most external battery packs available, is welcome to me. I think it’s good enough that the LithiumCard Pro only flashes white for high (90% capacity and above), red for low (10% capacity and under), and blue for everything else. With the 3000mAh capacity, most users might be using the whole lot in one go anyway.

LinearFlux LithiumCard Pro battery thickness

Measured in quarters, the LithiumCard Pro (left) and original (right)

The LithiumCard Pro has more going for it than sleek looks. USB cables are built in, one hidden on each side, so you can charge and recharge on the go. You’ve got the standard USB tip (power in) and a choice between micro USB and Lightning (power out).

Apple users can fear not, since the Lightning models are MFi certified. Each cable is made of a flexible, reinforced rubber that can hold some serious weight (e.g. dangling tablets, smartphones, portable speakers, etc). The cables on the Pro are twice the thickness of the original.

If improved cables and increased battery capacity wasn’t enough, there’s also a standard USB output port on one end and a micro USB input port on the other (right underneath the power switch). Each of these ports are covered by an attached silicone seal to keep dust, liquids, and anything improper out. Sure, you’ll have to provide your own separate cable to charge a second device simultaneously. But now when someone asks you, the reply would be, “sure! Do you have a cable?”, instead of, “No! MINE! Begone!

LinearFlux LithiumCard Pro battery microUSB

Micro USB input (left) and output (right)

Unfortunately, you can’t charge the Pro faster by having power going into both the USB cable and the micro USB port (confirmed, and then confirmed by testing).

Although the LithiumCard Pro is not likely to fit in your wallet, the included NanoStik pad lets you piggyback the battery on virtually any flat, smooth surface. Like the back of your smartphone or smartphone case. Or a book. Or a portable speaker. Or the back of your smartphone or smartphone case. Why get stuck by an outlet to charge your device when you can have a portable battery to charge on the go – why be inconvenienced by holding a portable battery in your hand when you can stick it to the back of your device with a NanoStik pad?

Did I mention that the LithiumCard Pro can also sync? That’s right. Not only do you have energy when you need it most, but you never have to worry about looking for a data cable when you want to transfer files. It doesn’t matter if there is power in the LithiumCard Pro or not. That’s an easy 2-in-1 right there, and there are very very few other external battery packs that can claim the same.

Battery Performance

Even though the LithiumCard Pro has a single LED in the shape of a wooden toothpick, it does a fine job at letting you know what’s going on with a single glance. If the LED is flashing, then it’s either in the process of charging up to full or charging out. If the color is solid (not blinking), then the battery is on but not connected to anything, and it will turn itself off in about 10 seconds.

LinearFlux LithiumCard Pro battery USB

USB output (left) and input (right)

You’ll know the LithiumCard Pro is totally empty when you press the power button and the LED remains dark. You’ll know the LithiumCard Pro is fully charged when you press the power button and the LED stays lit for about 10 seconds before turning off. It’s smart about detecting and shutting off quickly. All totally simple, very effective.

There is no auto-detect with this battery – you’ll have to manually press the power button each time. But it is smart enough to turn itself off (quickly) once a connected device has reached full charge. Keep in mind that the LithiumCard Pro is going to run warm/hot, far more than the wide majority of external battery packs do. It’s the trade for it going to work and pushing the amps!

The LithiumCard Pro advertises a total of 3A output, and it certainly makes good on that promise. By itself, my Lenovo S8-50 tablet can suck up power at the rate of 2.27A when it’s connected with a fast cable and wall adapter that outputs at 2.4A. The LithiumCard Pro output matches the same when it’s charging my Lenovo tablet. My Galaxy Note 4 smartphone tops out close to 1.7A with the same cable and wall charger, and the same rate is duplicated by the LithiumCard Pro. So far so good.

LinearFlux LithiumCard Pro battery dangling

That’s some serious tablet-dangling power!

When I try to charge my Galaxy Note 4 (via built-in cable) and the Lenovo S8-50 tablet (via cable and USB output port) at the same time, the LithiumCard Pro shuts itself off after about 30 seconds. That’s probably about the point when the demands of the mobile devices exceeds the 3A total output by the LithiumCard. The circuitry seems to work as intended – I’m not sure if it’s supposed to dole out measured amps when it wants to max-charge everything.

But the sweet spot is when I pair a low-demand gadget with either the tablet or phablet. If I have my spare Galaxy Note 4 battery+charger connected through a cable and the LithiumCard Pro output port, it draws 1.3-1.5A while the tablet/phablet runs at about 1-1.3A. Not too bad. Either way, it’s some pretty quick charging for such a small external battery.

The LithiumCard Pro also supports pass-through charging, where it charges itself and a connected gadget simultaneously. The rates for both the battery and second device run around 1.3-1.5A, pretty much maxing the 3A and 15W total output of the LithiumCard Pro. Again, pretty solid performance.

The LithiumCard Pro is supposed to be able to charge out at 1% battery per minute. I’m sure that this applies to most devices out there, and it actually comes pretty close to that rate on my Galaxy Note 4 with it’s sizeable 3220mAh battery. The LithiumCard Pro can fully-charge my Note 4 battery (in the case/charger) in 1 hour and 22 minutes (give or take a few minutes). Very close to 1%/min. My S8-50 tablet, with it’s huge 5700mAh internal battery, only gets 6/10th a percent per minute from the LithiumCard Pro. So there are some exceptions.

LinearFlux LithiumCard Pro battery nanostik

NanoStik pad comes with the Pro, just as good as ever

Note: Most external battery packs I’ve ever purchased and used came only partially charged, so I’ve always made it a habit to fully charge them before use. I tend to fully charge and discharge a new battery a few times, just so I can level out the charge states of the individual cells. It helps to maximize the battery’s manufacturer-listed potential.

The standard efficiency rating of external battery packs currently on the market is 70 percent. This means that 30 percent of the battery’s listed capacity is consumed while charging up devices. So, for example, a basic 1000mAh battery would effectively deliver 700mAh of energy.

Right out of the box, the LithiumCard Pro was able to deliver a total of 75 percent charge, or 2415mAh of usable energy, to my Samsung Galaxy Note 4 battery (3220mAh).That’s equivalent to 80.5 percent efficiency. Want to talk about impressive? That’s impressive. Additional charge cycles brought up the values to a peak of 79 percent efficiency. So far it’s only been 79 and 75 percent efficiency (for me) with nothing in between. It’s very consistent and stays in the stated “up to 80-85% efficiency!” range as mentioned in the campaign page’s FAQ section. But for the sake of under promising and over delivering, lets just say the LithiumCard Pro is good for 2415mAh two out of every three cycles.

So what can you do with 2415mAh of battery energy? That’s good for 0.75 full charges to a Samsung Galaxy Note 4 (3220mAh), or 1.33 full charges to an Apple iPhone 6 (1810mAh), or 0.53 full charges to a 7″ Kindle Fire HDX (4500mAh).


It’s safe to say that the LithiumCard Pro fully delivers on its campaign promises: 1 full charge to an iPhone 6 (with a little left over), 2 times the thickness, and 3A of output current. The HyperFET circuitry gets close to 1%/min charge on my Galaxy Note 4 phablet, which means ‘standard’ smartphones should charge even faster than that. The efficiency lands right in the range of what they have listed in the FAQ.

LinearFlux has upped the ante with the LithiumCard Pro by besting the original with significant improvements. Extra ports? Thicker cables? Data transferring? Excellent performance? And you still get an awesome NanoStik pad. It’s really hard to find any fault with the LithiumCard Pro. I think the team has done a great job at listening to user feedback and implementing those ideas into an even better product. It’s got a full feature set in a pocket size.

If you’re reading this before April 17th 2015, you can visit the LithiumCard Pro campaign page on Kickstarter to pledge for your own. If you’ve missed it, you’ll have to wait patiently for it to become available at the LinearFlux website. In the meantime, you can check out my video review of the original LithiumCard on my YouTube Channel for a quick summary of how it has held up after a year of use!

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  • Stanley Goodner

    Whoops! I just noticed a mistake in the charge/efficiency. My Note 4 had been receiving 75 and 79 percent battery charge, equivalent to 80.5 and 84.8 efficiency for the LithiumCard Pro. I must have gotten a little tripped up, since both battery capacities are only 220mAh apart!

  • JB

    Hi @stanleygoodner:disqus – if you had to choose one between the original and the Pro, which would it be? I can’t decide if the speed, power, and improvements of the pro trump the slim profile and easy carrying/wallet-friendliness of the original. Thoughts? (& thanks for the great reviews!)

    • Stanley Goodner

      It depends on the wallet! Personally, I favor the added capacity and enhancements of the Pro. I don’t actually put anything other than cards in my slim/minimalist wallet, favoring a palm-sized zip-case for all my EDC tech/gear instead. It’s just the way I organize. But if your wallet can comfortably fit the original LithiumCard, and if its capacity suits your needs, and if you don’t think anything will change any time soon, then the original might work well for you. Otherwise, if you get a new wallet that doesn’t fit the LithiumCard nicely, you might end up kicking yourself for not getting the Pro. Or you can get both and just have that much more mobile power :)