Yea, what he said. I bought 10 for 90 cents at my local electronics store and then bought a 6" extension, cut about an inch out of the red wire, soldered them in series and then put heat shrink tubing over it. Then all you have to do is connect it between the ignition and battery. It dropped the voltage to about 4.9v under a 500ma load on a 3/4 full A123 battery.