You can find more information about Nickel Iron batteries here.
Price: $175 per 10Ah Nickel Iron battery, plus shipping.
The batteries we use in our Iron Sun Boxes are custom made for Living Energy Lights by Troily, a battery company in China. Troily has taken the tried-and-true technology developed by Thomas Edison, and reconfigured the batteries to pack more power in a smaller package. These are high-quality, high-performance batteries, based on the same super-durable nickel iron chemistry that has been in use for over 100 years. If you want to build your own nickel iron off-grid system, we can offer you the batteries to do it. These batteries are rated at 10 amp hours at 12 volts. Their operating voltage is listed from 10.5 to 15 volts, though they can be charged as high as 16.5 volts. Nickel iron batteries will outperform other kinds batteries of a similar amp-hour rating, and will outlast other batteries by decades.