Turn Cordless Tool Batteries Into USB Chargers

It is the unspoken law of cordless tools – eventually you will have extra batteries lying around from dead tools that are incompatible with your new ones. Some people let them sit in lonesome corners of the garage or basement; others recycle them. [Eggmont] was facing this dilemma with a Makita battery from a broken angle grinder and decided to make a USB charger out of it.

[Eggmont] took the simplistic approach, using an old cigarette lighter-to-USB adapter. First, [Eggmont] removed the battery connector from the bottom of the broken angle grinder. Next, the casing surrounding the cigarette lighter plug was removed so that the adapter’s wires could be soldered to the contacts on the battery connector.  The USB ports were then glued onto the top of the connector. The adapter was rated 9-24V input, so it was fine to use it with the 18V tool battery. Since the battery connector is still removable, the battery can be recharged.

Tool manufacturers are tapping into the market of repurposing old batteries for charging mobile devices. Both DeWalt and Milwaukee Tool have now created their own USB adapters that connect to their batteries. Or, you can purchase the Kickstarter-funded PoweriSite adapter for DeWalt batteries instead. Compared to their cost, [Eggmont’s] project is very economical if you already have the battery at hand – you can find the USB adapter for less than $10 on Amazon.

Backseat USB Charger


Whether you’re relegated to the backseat of your ride or just strapped for access to power, you may benefit from adding your own backseat USB charger. While this is a fairly straightforward hack, we’re surprised at how clean it turned out and at the convenience it provides.

[wongman2001] started by grabbing a socket wrench and unbolting his seat from the rails in the floor. He then disconnected the electrical plugs for the chair’s heating and power seat adjustment. With the chair disconnected and removed from the car, [wongman2001] further dissected its components, removing its back panel and test fitting a female cigarette adapter. Though this seat had plenty of room near the headrest, you may need to carve out some foam for a snug fit in your vehicle. To source the needed 12V, [wongman2001] tapped into the wiring for the seat’s motor, then soldered and insulated the connections to the cigarette lighter jack.

Check out some other clean-looking car hacks like the hidden MP3/USB Aux hack or the Nexus 7 double-DIN dashboard hack.

Modding A Car Charger To A Variable Power Supply

For an upcoming road trip, [Patrick] needed a small variable power supply. Instead of lugging around a bench supply, [Patrick] did the sensible thing and reverse engineered a cell phone charger to fit his requirements.

After cracking open an old Kyocera car charger, [Patrick] found a small PCB with completely labeled, all through-hole components – excellent reverse engineering potential. After finding an On Semi MC33063 IC, [Patrick] tore through the datasheets, generated a netlist, and developed a schematic that closely resembled the reference schematic given by the datasheets.

With all the grunt work done, [Patrick] set out to finish what he started – modifying the charger to output 3-10 Volts. After replacing a resistor with a 5k multiturn pot, [Patrick] was left with a power supply with a variable output from 2.8 to 8.8 Volts. Not exactly what was desired, but more than enough for the application at hand. While this hack isn’t a disco floor, it’s a great walkthough of the hacking process – building or modifying something to suit a need.