ThruNite U1 Charger + 1x3400mAh 18650 Battery -- Multifunction Charger & Portable Mobile Power Bank

I wanted a power bank with a replaceable battery and this is it. My backup power is only limited by the number of batteries I have standing by. This will be great for camping or long walks.Update:I just sent the following to ThruNite and downgraded to 4 stars:The charger and battery are fine.PROBLEM: The included USB cord is useless. When I use it to charge my phone I get a notice on the phone that states "Slow charging" and instructs me to use a different usb cord.I tried three other usb cords I have from different manufacturers and they all work perfectly. You should not even be including your current usb cord with your U1 + battery bundle. You should include a different and better quality cord. I do not want to return the charger and battery so I will use my own usb cords with it.

This charger was surprisingly versatile. I purchased it to recharge 18650 batteries in the backcountry or emergency situation from goal zero solar panels. It works great for this purpose because it is very light and durable when the well constructed ballistic nylon case is used.What I was surprised to find is that this is very useful for keeping portable electronic devices charged while out and about. The charger / battery combination is so light you can keep it in your hand along with the device. You can attach the case to your belt and charge your device in your pocket and unplug it when you use it. The short cable that it comes with is the perfect length for this type of usage.If you need more charging capacity you could carry more batteries. If you use this so much that you wear out your battery, you can replace it with a standard 18650.The thrunite battery that is supplied is probably the best performing battery out there at a value price. The battery provides approximately one charge for my Samsung Note 3 in around three hours (this includes the phone being used for about half the time).The charging indicator shows red when charging the battery and green when fully charged. The charging input is a micro USB so you can use your wall chargers or vehicle chatgers. It takes around three hours to charge the thrunite 18650 and it does not become warm while charging.My phone has a battery that lasts around 8 hours of use. While not necessary, this charger is so convenient that I use it to keep my phone topped off. If you have a less efficient phone or failing battery, I could see this being used continually.I will buy more for my bug out bags and for other members of my family.

Some people will sell you this charger for $10. Others will sell you this battery for $13. For $20 you get the charger and battery together, saving yourself $3. And this battery is LEGITIMATELY 3400mAh. Why do I say legitimately? Because a lot of the 18650 batteries offered on Amazon don't come even close to their advertised capacity. Those who have bought any brand ending in -FIRE knows the disappointment of finding that the real capacity is only a fraction of the manufacturers rating. This battery gives you exactly the capacity stated.The charger is small (3-1/4 x 1-3/8 x 1 inches), light (37g - 1.3 oz), fully automatic, fully protected, and idiot-proof. You plug it into a USB power source, put in a battery and the red light comes on indicating charging. When the green light illuminates, charging is completed. If you put a charged lithium battery into the charger and don't plug in a power source, you'll notice a blue glow around its full-size USB port. The charger is now a 1A USB power supply. Note that this only works with lithium batteries. The reason is protection - a lithium rechargeable can be damaged if discharged below 3V. Therefore the power supply circuit turns off when the battery's voltage is less than 3V. That means a 1.2V NiMH cell falls below the cutoff voltage even when fully charged.Also note that you want to use a high-capacity USB port with this charger. The standard USB port only provides 500mA, and while it works, the battery will charge at less than half the speed it's capable of. The USB port should be one of the newer 1.3A high-capacity variety for the fastest charging. If you have a tablet or one of the "phablet" phones you can use it's charger - most of them are of this type.In addition to a USB-A to micro-USB cable, the charger comes with a ballistic nylon case, which is overkill in my opinion. I don't recommend using it while you charge - it has the potential to overheat your battery, which will reduce the charging rate as the thermal protection kicks in.In summary, if you need a small, light, fool-proof way to charge one battery while hiking, you will REALLY like this charger. If you do nothike, you may still like this charger as a portable unit for the car or work site, since it will work with your existing phone charger. If you only charge batteries at home, or need to charge several batteries at once, another charger will be a better fit for your usage.

I am a bit confused by some of the other reviews of this product that focus only on the battery. While that's certainly important, I bought this as a system: a charger plus battery which can be used with other batteries. As a system, for $20, I think this is a fantastic value.If I could give the U1 Charger 4.5 stars, I would have because it does, in fact, discharge the battery if you install it and have nothing plugged into the output port (there is a blue LED indicator that is lit while it is discharging). After charging the battery, I put a small piece of paper between the "+" terminal and the contact, as an insulator to disconnect the battery for storage. The alternative is to remove the battery altogether, but then it will not all fit into the nice ballistic nylon carrying case ThruNite includes with the system. ThruNite could have included an on/off switch for the discharge feature, but it would have added cost and a point of failure, so I'm only mildly annoyed by this. Overall this is pretty close to 5 stars for my use.