np40 is equivelant to ansi 300#
An np40 battery is mostly used for cameras. Depending on the type of camera you have the price varies. They are available almost anywhere you can buy a camera.
When it comes to powering items, it is important to use only the best batteries or energy around. This is where the np40 battery comes into play. One can find this energy source a few ways. These items are sold online and they can also be found in local stores. One should always compare prices to ensure that they are not overpaying when investing in such items.
There are lots of good websites that sell discounted electronics and batteries. You can look for one on Amazon's webstore, or on eBay. Both are good.
You can get this type of battery at Wal-Mart. You could also ask your technician where he would recommend you getting the battery at. He may even have some for sale.