Instruction: Answer the given question using the supporting document.

Input:
Question: How long can it last while not being used- will it lose battery strength over time? How much time?
Document: The build quality is great. You can probably find a cheaper battery but this one will last a long time. I have used it to charge every generation of iPad including the mini it also charges iPhone 5 and 4 great with no issue.
I have used it a couple of times and so far it does what it is intended for... it keeps the charge! I dont really know how long it last with the charge, because I bought it about 2 weeks ago... but I dont leave my house without charging it before I leave... I just dont want to find out! all I know is that it can charge my phone twice from 25% to 100% in about 2 hrs each time.
I thought the charge may last a little longer but I still like the portability of the charger. My phone battery doesn't hold a charge as long as it used to and I really don't want to get a new iPhone so this was a great solution. I only had my phone in mind when I bought this, but it never dawned on me that I could charge other devices as well!
awesome product.. well worth the purcase. Use this all the time and the battery life last long time before it needs to be recharged
Compact and quick! On the go, this unit is for you when you are traveling or not going to be by a power source. It's quick charging and the battery source last a long time. The Jockery Bar fully charged my iPhone 5s three times before having to recharge the bar.
I have an iPhone 5 and the battery doesn't last very long which is why I bought the Jackery. Not only does it charge the phone quickly but I get more than one charge out of it before I have to recharge it. The fact that I don't need an outlet is brilliant and saves me time trying to find one while traveling. I highly recommend this product especially if you're always on the go.
Just this morning I noticed my phone battery low but had to go out where I wouldn't have a charge source. I have a bag for it and put it with my phone connected to it, and by the time i needed it, the cell battery was at 100%. I don't know how many times I can charge it and for how many days it will last. I plan to try it out by not recharging it now to see just how long it will continue to charge my phone.
I don't understand why I keep getting asked to review this product. This is the last time I write about it. GET THIS PRODUCT if you want a single battery backup for portable USB devices, or if, like me, it's part of a several-leveled backup strategy for long-term power outages, which are unquestionably coming. I said unquestionably coming.
This little item has made my life so much better! I use a lot of battery power since I'm burning up data all day long. My phone was dead by dinner time. With this portable charger, I get the rest of the evening to talk or read. It's small,and  light enough to go in my pocket. It has lights to show the level of charge, as well as a little LED light to see to plug it in...haha.
This is not the first external battery I've purchased for my iPhone, but it's decidedly the best. I've been using the Jackery Bar for about a month. Anybody who's used older-generation batteries for charging mobile phones knows that the old chargers lost charge quickly and you were lucky if you could get more than a half charge out of the device before it ran out of juice. With the Jackery Bar, they promise it won't lose charge during storage.
Answer: Not really sure. However I have charged it and didn't use it for over 2 weeks , then charged 3 phones.