A few days ago, I had an itch to want to build a LED light for reading my Kindle 4 e-reader in dimly lit places. I had seen many LED lights for e-readers online for sale, however, all of them required separate batteries, were rather bulky, and had to be clipped on to your case or the Kindle itself.
I had seen that the official Amazon Kindle Lighted Case for the Kindle 4 didn't require any additional batteries as it was powered via the power pads on the back of the Kindle. So I thought to myself, why can't I make a small LED light and power it by tapping into these same connectors?
I scoured the Internet trying to find information on the electrical properties of the power pads on the back of the Kindle 4 e-reader. Much to my surprise, I was unable to find any articles, forum posts, or even tutorials listing how much current you could draw from the pads. So, I submitted a short request for any redditors that happen to own an official Amazon Kindle Lighted Case and a new Kindle 4 to measure the current draw of the case. Shortly thereafter, I had quite a few responses and the answers I was looking for.
I am creating this blog entry in hopes that if someone tries finding this information in the future, there will be at least one article that contains the information they are searching for.
Measured electrical properties:
- MAX Current Output: 57.0 mA
- Supply/Operating Voltage: 3.9 V
- Amazon Kindle Lighted Case's Actual Current Draw: 23.7 mA to 24.0 mA
Feel free to leave a comment in the comments section below if this information helped you.