The higher the value resistor, the longer it will take to charge, and the less current will flow across the resistor, making for less heat.
I wouldn't recommend using a resistor, simply because it's hard to determine when the capacitor is charged.
The easiest way to do it is to use a 12v light bulb. It's great if you can get one in a socket or something that gives you two wires coming from it so you can touch one end to your power wire, and the other to the cap terminal.
(you can go to the parts store and get creative - or you can use an LED, has to be 12v though - or you can solder wires to the lightbulb, one to the contact on the base, the other to the barrel of the bulb)
But anyway, car parking lights or turn signal lights are usually good because they aren't that bright - meaning lower wattage meaning higher resistance... good for our charging purposes.
Anyway - this is real easy.
One of the light bulb wires you hold to the capacitor terminal.
The other light bulb wire you hold to the 12v power wire.
Initially, the light (or LED) will light up quite bright. This simply indicates that the capacitor is charging. how cool is that?
The light will slowly dim as the capacitor charges.
When the light goes out, you know the capacitor has fully charged to whatever level the electrical system happens to be at at the moment (probably 12.5v or so, with the key off).
Now you can connect the power wire to the cap and be on your way.
You could use a resistor - the value isn't terribly important - but you'll likely want to hold it on there for a good few minutes just to make sure. Don't get one that's too large if you do it this way.
The higher the value resistor, the longer it will take to charge, and the less current will flow across the resistor, making for less heat. ;)
I wouldn't recommend using a resistor, simply because it's hard to determine when the capacitor is charged.
The easiest way to do it is to use a 12v light bulb. It's great if you can get one in a socket or something that gives you two wires coming from it so you can touch one end to your power wire, and the other to the cap terminal.
[i](you can go to the parts store and get creative - or you can use an LED, has to be 12v though - or you can solder wires to the lightbulb, one to the contact on the base, the other to the barrel of the bulb)[/i]
But anyway, car parking lights or turn signal lights are usually good because they aren't that bright - meaning lower wattage meaning higher resistance... good for our charging purposes.
Anyway - this is real easy.
One of the light bulb wires you hold to the capacitor terminal.
The other light bulb wire you hold to the 12v power wire.
Initially, the light (or LED) will light up quite bright. This simply indicates that the capacitor is charging. how cool is that?
The light will slowly dim as the capacitor charges.
When the light goes out, you know the capacitor has fully charged to whatever level the electrical system happens to be at at the moment (probably 12.5v or so, with the key off).
Now you can connect the power wire to the cap and be on your way. :cool:
You could use a resistor - the value isn't terribly important - but you'll likely want to hold it on there for a good few minutes just to make sure. Don't get one that's too large if you do it this way.