Run an 18V Ryobi Tool Using a Car Battery

Special battery packs often fail. Wouldn't it be great if you could run your 18V device off a car battery instead? You'll of course lose some speed and/or power, but it can be done. Here's how with a Ryobi 18V One+ reciprocating saw.

Steps

 * 1) Cut 7 or 8 inches off a length of 1.125" (1 1/8") diameter dowel rod. The extra length gives you something to grab when inserting and removing this replacement for the battery pack.
 * 2) Cut about 4 inches from a piece of 3/4"x1/8" rectangular aluminum stock.
 * 3) [[Image:IMGP1089_981.JPG|thumb]]Drill two holes in the aluminum stock, at about 1/2" and 1" from one end, at about the center. See where the screws are in the photo; that's where the holes were drilled.
 * 4) Holding the other end (that which you didn't drill) of the aluminum piece flush with the end of the dowel, screw the aluminum to the dowel with small wood screws. Drill pilot holes first if necessary.
 * 5) [[Image:IMGP1090_540.JPG|thumb]]Cut half-moon shaped notches into the end of the dowel at about 2 and 10 o-clock, with the center of the aluminum as 6 o'clock. See the notches in the photo for clarification.
 * 6) [[Image:IMGP1092_951.JPG|thumb]]Push the dowel into the tool, aligning the aluminum with the flat side of the battery compartment, making sure the notches are big enough to enable the dowel to seat completely. Adjust until it fits. Don't force it and bend the metal connectors at the base of the battery compartment; this carving is to ensure it goes over them.
 * 7) [[Image:IMGP1091_285.JPG|thumb]]Connect the two wires, using wood screws, to the end of the dowel, such that the stripped and twisted wires stay in the notches. Make sure the positive (red) wire is on the left with it held upright as seen here; it will be on the right when you invert it and push it into the battery slot.
 * 8) Clip the battery leads, red to positive (+) and black to negative (-), to your car battery or 12V solar setup.
 * 9) [[Image:IMGP1094_921.JPG|thumb]]Plug the dowel into the tool, seating it completely, and making sure the wires stayed put as you pushed it in.
 * 10) Safely turn on the tool and make sure it works.

Tips

 * This basic idea can be adapted to make battery eliminators for just about any low-voltage device, by determining where the positive and negative connections are, and what combination of readily-available supplies can be put together to fit in place of the battery.

Warnings

 * This procedure, when adapted to a 12 or 14 volt device could likely be used indefinitely. When connected to a tool requiring a higher voltage, it should not be subjected to prolonged use.  When voltage is reduced, the amount of current or "amps" in the circuit increases to compensate.  All conductors (wires, cables and motor windings) in the tool are sized for a certain amount of current, to safely carry the "load" and prevent heat.  If more current flows in the circuit than designed, excessive heat results.  Enough heat will eventually cause the tool to fail or possibly ignite.


 * A car battery can produce enough power to arc weld steel. When using any electrical power source, ensure that all circuits have appropriate current limiters (Fuses, circuit breakers, power regulators) to prevent fires.


 * Remember that you are using up the energy in your car battery, so after extended use, you might not be able to start it afterwards.


 * Draining the battery too much could permanently damage it. If possible, connect a Voltmeter to the terminals, don't let the battery drain under 10.5V during load, or 11.8V open-circuit.

Things You'll Need

 * Length of 1.125" (1 and 1/8 inch) diameter dowel
 * Length of .75" (3/4 inch) wide by 1/8" wide aluminum rectangular stock
 * Two pieces of stranded wire, recommended 12 gauge or larger, with battery clips on the ends
 * Two #4 to #6 wood screws, 1" long or less
 * Two #10 or #12 woods screws, 1/2" long or longer
 * Tools, including a hacksaw, screwdriver, and pocket knife

Related Tips and Steps

 * How to Make Battery Eliminators
 * How to Run Your House With Solar Power

Sources and Citations

 * This research was made possible, in part, by a land grant from the City of the Sun Foundation, though the specifics of the research were not coordinated nor endorsed by COSF.