[Rusdy] is building a solar charger for his electric bike, and quickly realized the lithium cells in his bike wouldn’t work well with the most common charge controllers out there. Solar cells have an IV curve, of course, and this changes with the amount of sunlight, requiring some conversion circuitry. Most of the charge controllers out there operate in buck mode, but the commercial boost mode converters [Rusdy] needed for his 36V battery are pricey as all get out. What was [Rusdy] to do? Build his own Boost MPPT solar charger, of course.
The circuit used for the charge circuit is fairly similar to a boost converter, with a little bit of logic required to get the maximum power out of the solar cells. [Rusdy] had an Arduino lying around, so that took care of the logic, and by sampling the voltage and current with the analog pins, he can turn a MOSFET on and off to get the most out of his solar cells.
The finished product works perfectly with an efficiency greater than 87%. Charging current and the final trickle charge is adjustable through software, allowing [Rusdy] to get the most out of his solar panels and electric bike. The board itself is just a prototype and could use a layout revision, but we’ve got to hand it to him for cloning a >$300 charge controller with an Arduino and a few scraps in a part drawer.
What’s the size of a deck of playing cards and can pump out enough power to charge your cellphone? These awesome little home-made magnetic solar panels!
[Christian Pedersen] has just published a guide on how to make these handy little solar panels, and they only cost about $1.25 each! They are capable of providing between 0 – 0.5V at 400-1000mA depending on the light available and load being driven.
All you need to make them is some multicrystalline solar cells, copper tape, Ethylene-Vinyl Acetate (EVA — a film used to protect solar panels) and Polycarbonate sheet for the external hard case. You can then assemble them in a matter of minutes, and laminate for a permanently sealed panel. He’s also added thin neodymium magnets so the panels stick together when you arrange them in a line! Perhaps a future version could have the copper strips going in both directions to allow for larger arrays to be made.
He also has a complete BOM on his GitHub, and if you happen to be at the Maker Faire in San Mateo in May, he’ll be showing you how — in person!
Let’s face it — solar panels still aren’t that efficient. So why not pump as much juice out of them as possible? Building a 2-axis solar tracking unit can increase daily power output by around 30%!
[Jay Doscher] had his power go out back in 2011, and even though it was only for 12 hours, they realized how ill-prepared they were to deal with a power outage. Food was spoiled, flashlights were dead, candles were sparse… they needed to be prepared better for the next time this happened. This spawned one of [Jay’s] longest running projects on his blog Polyideas.
His goal was to build a fully automated solar tracking unit that could be setup anywhere, and automatically track the sun to ensure optimum ray catching. It makes use of a 12V gear reduced motor to provide panning, and a linear actuator with positional tracking to control the tilt. To track the sun he’s got a digital compass and an Adafruit Ultimate GPS breakout board. To control it all he’s using is an Arduino UNO, but he has been through multiple iterations including his first with a BeagleBone. It’s a very slick and well engineered system and [Jay’s] hoping to spread it around the world — the entire thing is open source. What a guy!
It’s not quite complete yet, but he’s got an amazing build log and a GitHub repository filled with info — plus the following video showing it off in its current state!
Continue reading “2-Axis Solar Tracker Always Gets a Tan”
Here’s a cute little LED hack for your next soiree, it’s a solar charged piece of wood… with a motion controlled light in it!
[Zach DeBord] decided to try building his own version of this after seeing a commercial offering. He took a piece of oak and sliced off the top edge, and then laser cut the exact profile of the solar panel out of that slice. This allowed him to drill a nice big sloppy hole in the middle of it to fit the circuitry.
He’s using a nice big 8mm LED with a small 0.09V-5V DC boost circuit, a mercury tilt switch, a 4.5V solar cell, and a 2.7V 10MF super capacitor — plus a diode and 100ohm resistor. He’s glued the top slice of wood back in place, and sealed the entire thing with resin — you can hardly see the cut mark!
Continue reading “Cute Tilt Beam Flashlight Adds Some Fun Interaction to Your Patio Table”
While browsing through his local dollar store, [Taylor] came across a suspicious looking rock that, upon closer inspection, turned out to be a solar garden light. He scooped it up, took it home and cracked it open, modding it to function as a handheld solar flashlight.
Inside was a pathetically small 40mAh rechargeable battery, which he upgraded to a more standard rechargeable AA. The garden rock came pre-built with its own boost converter to kick up the voltage for the LED, but it was fairly dim. We’re guessing [Taylor] didn’t bother reverse engineering the converter and instead simply did some trial and error, but he managed to increase the LED’s brightness by slapping on a different value inductor.
As fun as it may be to have a rock for a flashlight, [Taylor] decided to cobble together a custom case out of a spare USB charger, making a battery holder and adding a pushbutton. The result is a handy solar flashlight that takes around five hours to charge. Check out some other custom lights: a lithium-powered PVC flashlight or one with a snazzier aluminum body and interchangeable heads.
Despite this being [Kenneth Finnegan’s] first Burning Man, the guy came prepared and stayed connected by setting up a beefy electricity supply and a faint yet functional internet connection. If you saw [Kenneth’s] Burning Man slideshow, you know that the desert is but a mild deterrent against power, water, and even temporary runways.
He borrowed a 20V 100W solar panel from Cal Poly and picked up a bargain-price TSMT-20A solar charge controller off eBay. The controller babysits the batteries by preventing both overcharging and over-discharging. The batteries—two Trojan-105 220Ah 6V behemoths—came limping out of a scissor lift on their last legs of life: a high internal resistance ruled out large current draws. Fortunately, the power demands were low, as the majority of devices were 12VDC or USB. [Kenneth] also had conveniently built this USB power strip earlier in the year, which he brought along to step down to 5VDC for USB charging.
Internet in the desert, however, was less reliable. A small team provides a microwave link from civilization every summer, which is shared via open access points in 3 different camps. [Kenneth] pointed his Ubiquiti NanoStation at the nearest one, which provided a host of inconvenient quirks and top speeds of 2-20kBps: enough, at least, to check emails.
After the headlight on his bike died, [Patrick] decided this was the best time to hack the remains and solve a few problems: namely a constantly drained battery from accidentally forgetting to turn the light off. He opted for a solar solution, as he already had both an Adafruit solar lithium charger and a Seeed Li-po Rider. [Patrick] picks the Adafruit board for its extra safety features like temperature sensing to prevent the cell from overheating.
The build uses 9 eBay-sourced 2V mini solar panels attached neatly on the bike’s mudflaps. Three groups of 3 panels in series provide the needed 6V into the Adafruit lithium board which safely charges a spare 900mAh Nokia phone battery from the junk drawer. [Patrick] admits this solar setup may be overkill. He decided to include a USB jack to keep his phone charged for some Google maps navigation. The Adafruit board does not step up to 5V, however, so [Patrick] tacks on a Mintyboost kit to kick the Lipo’s output up high enough to charge the phone.
Solar’s not the only alternative way to power your bike’s lights. Check out the RattleGen from earlier this year if you missed it.