very poor life in my iPhone 5s can i get new battery

Make an appointment at the genius bar. If they test it and the battery is bad, then you can get the battery replaced. If it's under warranty, and the phone is not physically damaged, there should be no charge. If it's out of warranty, you will have to pay for the battery replacement.

I would second KiltedTim's response to you as the best option ...

However, if you are a do it yourself-type, your other option is to change the battery yourself. If you think you may want to attempt this, check out this iFixit link. Please note, that in addition to a new battery, it will require a number of tools that you may not already have ... but iFixit can provide you.

Please also keep in mind that if you opt to try and replace it yourself, you will render the phone completely unserviceable by Apple.

There are probably thousands of possible causes of poor battery life, and battery failure is the least likely among them. But Apple can test the battery and tell you if it IS the problem.

I second Lawrence's post.

Everyone think they have a bad battery...

It's either software issues (most likely), low cell signal, or liquid damage.

If it's a newish phone it is most likely not the battery.

One of the best ways that you can test the battery is to charge the battery to 100%, close all programs, restart the iPhone, turn brightness to about half, plug in some headphones (not wireless), set volume at about 50%, and start a movie. The original battery should last about 10 hours for video playback. Over time the battery will not last as long but I believe Apple won't replace a battery unless it performs less than 50% of the original capacity within the warranty period. If you end up getting more than 5 hours of video playback then it most likely will perform within their acceptable range and they will not replace it.

Good thought, but it is impossible to close all programs. While you can remove them from Quick Launch, if any receive notifications their background processes will restart. And built in apps can not be killed from the quick launch screens. They disappear, but are still running. So this is not a definitive test. If you do get 5-10 hours your battery is OK, but if you get less that is not proof of a bad battery. Apple's test (which can be done remotely) is the only definitive test for identifying a bad battery.

One symptom that DOES mean a battery is going is if the phone shuts off before the battery reaches 1% repeatedly. Or if the displayed state of charge jumps around. But even then Apple's battery tester is the most reliable way of checking a battery.