The week kicked of with more data collection on our cell phone charging process. We've been charging it mostly directly off the 6V battery with varying resistances in between, usually between 1 and 10ohms. This approach seems to be working very well at the moment and has giving promising results. However, the 6V battery is used in what EcoSystems calls the UserBox, a small wooden box with some internal circuitry that protects against discharging the battery too much or too fast. This box uses an RCA jack as its output, and between tricky connections there and funny electronic behaviour going on inside the box, it's actually pretty hard to get the mobile phone to charge off the RCA jack. Mainly because the boxes are design to cut off current when it hits 400mA, which the mobile phone sometimes does.
A photo of the UserBox on the right.
Our ultimate solution has been to just provide a mobile phone charger that works off the 6V batteries. Firstly because it is easier and cheaper to make these and everything that is needed is locally available, if not just over the border in China. And second because we have seen that 6V batteries like the ones we use are more common in the market than we thought. Providing a charger that works directly off the 6V batteries would allow anyone with a battery of that type to use them, and not just those that have bought the UserBox. The catch is that we want to protect the battery from over discharging, for what I will be trying a cheaply assembled Low Voltage Disconnect (LVD) to go on the charger this week.
Our office, with Mike diligently reading company emails.
The photo below deserves some comment. It is the most useful thing I've created at the office so far. On the far right you can see a Step-Down Switching regulator, a more complicated charger that turn out to be inapplicable within the parameters that we are working with. On the middle left there's a Low-Voltage Protection circuit used with the 12V batteries that are charged with the PedalPower generator. I assembled it with the purpose of testing 11V Zener diodes one by one. And on the top and bottom of the board you can see a bunch of LEDs, 55 in total. This is what I call the Mobile Phone Discharge Unit (MPDU). It is used to discharge the mobile phone battery fast enough so that we don't have to wait too long and slowly enough so that we don't damage the battery. When first assembled I was fascinated by the fact that your tiny and seemingly weightless mobile battery could power so many LEDS. You could light up your whole house with your phone!!!!
On account of this new discovery, which I made about 2 months ago I had a funny and awkward encounter with a shop owner. A while I found myself in the market for light sensors. I new where to find them but I didn't know what they looked like. When the man behind the counter gave me an LED looking thing, I gave him a skeptical look back. I really didn't trust this man, or at least not his knowledge about electronic components so I had to find a way to test this LED looking thing on the spot. Naturally I figured that if it was an LED it would light up with any mobile phone battery at hand. Damn! I left the mobile at home... So I ask the shop owner if I can borrow his mobile. As I start to take it apart in order to use the battery, Mike jumps in out of nowhere and demands me to stop. He found it rude and impolite. As a good friend I am, I followed his judgment and bought the 'light sensor' without testing it. The afternoon ended with my retreat back home, sad and regretful of losing the opportunity of using some random person's phone to light me up.
As the working week continues, Mike and I celebrated that it was Wednesday yesterday. After merry times by candle light and the bottle of Mount Everest whisky, it was time to hit the street food. Puri Sabj, cream roll, street momos and yogurt with cereal bars all made our night, each one of them for about $0.50 or less. The beauties of the sub-continent are endless.
Street buffalo momos on a leafy plate.
As for today, we have been told to work from our flat due to bandas (protests) going on all over the city. Just yesterday there were 2 young adults killed by people that claimed the murders to be on behalf of the Youth Communist League, and the whole country seems to be rioting about it today. Many businesses are closed, cars on the streets are few and UN and Red Cross convoys seem to be everywhere.
2 comments:
i hope the LED thing ended up working! haha you just started taking his cell phone apart..
its crazy a phone battery could charge your entire house, how long would it last though?
and street buffalo=crazy!
MV
It did work at the end. It doesn't last too long though. You'd be lighting up your house for 45min or so if the battery is fully charged.
Which is actually quite a long time if you think about it, if you are using your cell phone to light up the room in an emergency.
Check the photos in the next post, there will be one of the cell phone battery lighting up 55 LEDs.
Post a Comment