Build A Smarter BatteryBy Patrick Cameron
You break down on the side of the road, only to find your cell phone is as dead as a doornail. Or, you're out of the office and you've got a meeting that you think starts in an hour, your Blackberry just shut down so there's no way of knowing. Dead batteries can really put a cramp in our electronically-charged lifestyle. It doesn't have to be that way. Not if you take the advice of Ejaz ur Rehman from Electronic Design and create your own smart battery.
I, for one, know that this article could have saved me from some fairly harrowing moments last fall. I was fishing with my father. We had gone out early in the morning and I had neglected to check my phone battery before we left. My dad, being over 80, has never in his life owned a cell phone and that's not going to change anytime soon.
We're in the middle of the lake, and it's a big lake, in a 12-foot Alumacraft with a 1960's Johnson outboard on the back and a slow leak around the bung. Around noon, I noticed that the boat was taking in a little water. No problem. All we have to do is start the motor, get the boat moving, and pull the bung to drain the water out of the boat.
Well, it was at this point that the motor decides to stop working. To make matters worse, the sky is darkening overhead, the clouds are full of rain and there's not an oar in sight. So, as the water grows deeper in the boat and the waves get bigger, I do what any self-respecting urban fisherman would do... panic. When I go for my phone, I find the battery has dwindled down to nothing.
And this is when I start thinking about the Electronic Design article.
They outline the parameters of how to design an automatic battery charger for handheld devices. The charger uses a circuit built around a single transistor. Using a precise variable voltage supply, they are able to set both a high and low voltage level for the specific device, so that when the battery level hit a pre-established low voltage, the charger would automatically kick on, charge the battery, and then shut back down once the voltage has reached a preset high mark.
That's precisely what I'm thinking about as we are sinking in the middle of the lake. If I had had something like this on my phone, I wouldn't have been nearly as freaked out. I would have simply called the Coast Guard... or whoever... because my phone wouldn't have been dead. The good part is, a couple of guys in their walleye boat happened to see our distress and came over to make sure everything was okay. They gave us a tow back in and we survived a day with a dead cell phone battery and a hole in our craft.
So, next time you get in a bind because of a dead battery, think about Electronic Design's smart battery.