Here’s a project that let [Rick Pannen] try his hand with an OLED display and a rechargeable power source. He calls it OLEDuino which is a mashup of the display type and the Arduino compatible chip running the whole thing. He figures it will serve nicely as a geeky name badge but also ported a Breakout type game to play when he’s bored.
The project is an inexpensive way to attempt a more permanent trinket than simply using Arduino and a breadboard. [Rick] sourced the OLED display and USB LiPo charging cable on eBay. The ATmega328 hiding below the display is being driven from the 3.7V LiPo cell without any power regulation. The four buttons at the bottom provide the only user input but it should be more than enough for a few simple tricks.
Head over to his code repo for a bit more information. The schematic and board are both Eagle files. We generated an image of the schematic and embedded it after the break if you want to take a quick look at how simple the hardware really is.
Continue reading “OLED name badge with rechargeable LiPo cell”
Want mobile power for your Stellaris Launchpad development board? [Philipp] was looking to add some lithium power for the Launchpad. He used an off the shelf single cell LiPo battery and connected it to the 5V rail of the Launchpad board. It didn’t work.
So [Philipp] started looking through the schematics and noticed that the regulator was working fine, but the Stellaris wasn’t starting up. He tracked down a voltage supervisor connected to the Stellaris reset pin. After some investigation, it was clear that this supervisor was holding the device in reset.
The solution is a quick and dirty hack: cut the trace that connects the reset line to the voltage line. With this modification, the device starts up from the LiPo without any issues. [Philipp] does note that you should be careful about battery under-voltage and over-voltage. This hack doesn’t handle charging the LiPo battery, but we’ve discussed that in the past.
If you’re building solar vehicles at a competitive level you’ve got to know exactly how the storage batteries will perform. To that end [Matthew] built a Lithium Polymer battery tester for use by the McMaster University Solar Car Project. It worked well, but could only test one battery at a time. He just finished up a second version, which can test battery specifications on up to eight units at once. It saves a lot of time, but still takes fifteen hours to test just one set of the units used by the vehicle.
The most important aspect being measured is the discharge curve. Sure, there’s a datasheet that includes this information, but how can be sure that what you received will perform at spec? Each of the eight channels can be disconnected from the system using a relay. This is just one of the safety features which watch for things like over-voltage and over-current conditions. Remember, Lithium batteries can heat up fast if there’s a problem. Data is sampled on a 12-bit ADC and can be pushed to a computer via USB for graphing.
When [Soo-Hyun]’s friend had an Apple Macbook Pro battery that began to swell, his friend did the reasonable thing and donated it to be used in a robot. Now [Soo-Hyun]’s kiwi drive robot is powered by a gigantic LiPo battery, giving it a huge range and a very fast top speed.
The defunct laptop battery that formerly powered a 15″ macbook pro is three battery packs of two cells in parallel, delivering 12.6 Volts. To get the power to the robot, [Soo-Hyun] etched a simple PCB that fit into the slot in the battery. A little bit of soldering later, and mounting the battery as a shark fin because of the 8×8 inch limitation of maze-solving robots, the power plant was complete.
Using a bulging LiPo battery probably isn’t the smartest idea (listen for the great line, “it got the camera and my face” at 4:08), but as long as [Soo-Hyun] keeps an eye on the battery as it’s charging, it should be alright.
Check out the video of the robot zipping around on 12.6 Volts after the break.
Continue reading “Powering a robot with a macbook battery”
[Brian Knoll] still uses his Super Nintendo with relative frequency, and he just can’t get enough Super Scope action. If you never owned one, the Super Scope can be a ton of fun, but it’s also an incredible battery hog. It eats through AA batteries by the caseful, so [Brian] wanted to make the switch to rechargeable cells. Since NIMH AA batteries just don’t cut it in the Super Scope, he put together a rechargeable solution of his own.
He started off by calculating what sort of battery he would need for 8 hours of game play, then he started work on designing his circuit. The board he built contains both a DC/DC converter to provide the 9V required by the Super Scope, as well as built-in LiPo charger. He had his board made by BatchPCB, and after working through a small production error, he put everything together and gave his revamped scope a shot.
Things worked great, and while he says that he really should have built a low-voltage shutoff into his circuit, he is very happy with the results.
[Punish3r] wanted to have power for prototyping on the go. What he came up with is this little thing above. Inside you’ll find common components that let the unit provide 10 amp hours of current with a 12V 500mA output.
The storage capacity is provided by a dozen Lithium batteries. These 3.7V cheapies are wired in parallel behind a protection board. For charging and discharging, a Sparkfun LiPo charger board was used, taking care of all the work necessary to top off the batteries using a wall-wort. The final piece in the puzzle is a boost converter that provides the regulated 12v connected to the red and black banana plug receivers on the bottom of the case.
This is very much a plug-and-play design… just make sure you hook the parts up correctly and you’re up and running. We would love to see a roll-your-own boost converter circuit that include a switch or dial that lets you select common PSU voltage levels. If you’re going to the trouble to make your own board you might as well incorporate the charging circuit at the same time.