My friend just got a new 1.5 farad capacitor w/a digital readout but when hooked up the digital readout does not come on but i read 12v on the wire to the cap and 12v on the wire leavin the cap but when i actually measure the cap itself it declines in number. What is going on?
There's a positive and negative terminal on the cap. The power wire from the battery and the power wire to your amp(s) should be connected TOGETHER on the positive terminal and the cap should be grounded to the chassis on the negative.
Don't just hook the thing to ground. If you're not getting voltage off the cap that means its either "broke" or isn't charged. Make sure you use the lightbulb/resistor that should have been included to charge up the cap(temporarily ground it through the bulb) before permanently grounding it otherwise you could end up welding your ground wire to the chassis or the cap and/or burning yourself.