iPhone 5S says it's charging, but is steadily discharging?

It's plugged in, but it could be drawing more current than it's taking in. I've seen that before when I was using a 700 mA lighter plug adapter - where the percentage was steadily going down while I was using Apple Maps.

brianfrommerrifield wrote:

Thanks, it does charge on a 2.0 amp charger. Just not working well on any of my standard apple iphone chargers.

In that case it doesn't sound right. At 2A that shouldn't happen. There should never be a steady current draw greater than that.

You can check how much current it's actually pulling in. There are inline USB current/voltage analyzers that are pretty cheap.

usb power meter | eBay