Boost Peak Power Tracking Battery Charger

May 5, 2014 by Brian Benchoff 25 Comments

[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.

60 Watt Solar Panel Built From Cells

September 14, 2008 by Jason Rollette 20 Comments

Our love for solar projects continues on with this method to make your own solar panels. [Mike] built a 60 watt solar panel from individual solar cells he purchased off eBay. Procuring parts off of eBay normally causes others hardship when they try to duplicate the project, however in this case there are so many types of cells people can use to produce their own unique solar panel. Even cells that are extremely damaged my still be used, as in this example. To charge a 12 volt battery the number of cells in series just needs to be 16-18 volts, and the rest in parallel will supply more current. Charging a battery without a charge controller is not recommended, but commercial ones are easily had. Those not interested in jumping all the way in with solar may want to test the waters by building their own panel and putting it to use as a charging station for your portable gadgets.

Solar Backpack Ipod/usb Charger

October 28, 2006 by Will O'Brien 24 Comments

Jason sent me his solar ipod charger how-to. The regulator may not be neccesary – but there are so many models, I don’t know if the new Nano’s hold up to the old power input standard. He put a 7805 regulator on a 6v 100ma flexible panel that he mounted on his backpack. I’ve seen this sort of thing on a shuffle before, but this one should work for most iPods. USB power management sometimes shoots itself in the foot, but iPods are willing to pull power if it’s not present. It’s nice, clean and simple. I’d consider adding some high temp hot glue (or epoxy)to keep the soldered connections from breaking.