I am making this discharger, i have completed everything except the resistor. I am trying to work out what resistor i will need. I have put my multimeter on the battery as it discharged, the relay switched off at 3.5 volts, but then after about a minute, the battery levelled out and stopped at 5.5 volts. What number number should i put into the calculation? 3.5v or 5.5v? The resistor value is calculated by using: R = Rr(Vc/Vr) - Rr Where: R is the resistor value Rr is the resistance of the relay coil (92 ohms) Vc is the cut off voltage required (5 volts) Vr is voltage at which the relay releases (3.5 or 5.5 volts) r = 92(5/3.5) - 92 = 39.43 r = 92(5/5.5) - 92 = -8.4 What resistor will i need, like 1/4 watt? Cheers