This one would make a nice centerpiece for your Halloween party. It’s a battery with tiny pumpkins serving as the cells. [EM Daniels] shows us how to clear out the pumpkins, fill them with some freshly mixed electrolyte, and he even throws in the directions for baking the pumpkin seeds.
Each pumpkin will need a pair of conductors made of dissimilar metals to serve as the anode and cathode. Copper wire is used for one, aluminum for the other, and both wires have a spiral pattern bent on one end to increase the surface area that contacts the electrolytic solution. Now just boil up a slurry of vinegar, gelatin, and salt, then let it sit in the fridge over night. [EM Daniels] was able get 1.5V out of this project (enough to light one LED) for two hours, and 1.4V for six hours by using seven of the pumpkin cells in series.
Lithium battery packs reaching the end of their life usually have a lot of kick left in them. That’s because they’re made up of multiple cells and it only takes the failure of one to bork the entire battery. One of the most interesting examples we’ve heard of this is in the Toyota Prius, but that’s a story for another time. In this case, [Mika] wanted to resurrect the battery from his IBM Thinkpad T40. He identified the offending cell and replaced it, but couldn’t get any juice out of the battery after the repair.
He was measuring 0V on the output, but could measure the cells instead of the control circuitry and was getting over 11V. Clearly, the control circuit wasn’t allowing an output. We completely understand the concept here (think about that really bad press about exploding laptop batteries). It seems there’s a lockout mechanism when the control circuit loses power. [Mika] managed to get past this by shorting voltage into the control circuit, a method he likes in the video after the break to jump starting a car.
We’ve seen similar cell replacement for power tools, like a Dremel or a Makita drill.
Continue reading “Who knew Thinkpad batteries require a jump start?”
You can make your own lithium-ion batteries if you have a source for individual cells and a control board to match your desired voltage levels. [Bill Porter] put together a quick tutorial where he makes a 14.4V 2.2 AH battery for about $10. He picked up a set of cable-modem backup batteries (used to make sure your bundled phone service doesn’t quit working when the power goes out) and tore out the cells. After reconfiguring the connections and swapping out the controller board the original 8V battery is now 14V. This doesn’t take into account any problems with battery life and charge leveling, but that’s a whole different tutorial waiting to happen.
If this type of battery hack is child’s play to you, take a look at a more involved lithium iron phosphate build.
Open source GSM cracking software called “Kraken” has been released into the wild. You may recognize some of the information from back in December when we announced that they had cracked GSM encryption. Well, now you can participate as well. You’ll need a pretty beefy Linux machine and some patience. They say that an easier GUI and support for GPU processing is coming in the near future.
[Thanks Eliot Via Slashdot and PCWorld]
[Dave] Had been working on a cell phone activated remote start for his car for a while when we posted the GSM car starter. While both do carry out the same job, we feel that there is enough good information here to share. He’s gone a pretty simple way, by connecting the vibrator motor leads to a headphone jack. He’s using that signal to then activate the remote start by setting off an extra fob. Though it is amazingly simple, this version does have an advantage. As [Dave] points out, his cell phone has several features which could be utilized to automate some of his car starts. He can set alarms as well as recurring calendar events to get his car started without his interaction. Lets just hope he doesn’t forget and let his car run too long unattended, especially if it is in a garage attached to his house.
[Rob] grew tired of his Makita power tool battery packs dying so he figured out how to repair them himself. The video after the break walks us through the process which starts by cracking open the case. Inside there is a controller board and a battery of ten cells. [Rob] has pinpointed these battery failures to just the first cell, which is confirmed by measuring the cell voltages with a multimeter. The first cell in the demonstration battery reads zero volts and needs to be replaced. For some reason he’s got heck of a lot of these cells on hand, at the end of the video he shows off a massive block of them that provides one half of a kilowatt-hour of power.
To complete the resurrection he removed the control circuitry from the integrated PCB. It seems that the microcontroller on the battery’s PCB monitors it and bricks them when it thinks the life of the unit has ended. By hacking a charger he can now balance-charge the altered battery packs and get more use out of them before they hit the landfill.
Continue reading “Makita battery pack repair”
[Dan] set up this simple cell phone hack to disable his microphone when he’s not using his cell phone. He had read that the government can listen to you using your cell phone, even when it is off. This concerned him enough to hack into his phone. He removed the expansion port and wired the microphone to a magnetic reed switch. A strong magnet located in the screen side of his flip phone opens the circuit when he closes the phone. He notes that you could always just pop the battery out of your phone, but then you are left completely disconnected. This mod allows you to still receive phone calls.