Ive done a search but havnt found an answer

i am wondering if it is ok to use more than one 1farad capacitor when u have less than 1000watts.
my amp is 840watts in 4ohms but id like the look of 2 digital capacitors.

also does it make a difference if i get the 24 volt or the 30 volt surge caps. (higher is better right)

also more important, whats the maximum length a cap can be from the amp. lets say i want to put the amp on the left side of the trunk/hatch and the caps on the other side of the trunk/hatch. is that too far plus snaking the wires around the trunk.

 

Jimmy - 1 farad/1000 watts is just a rule of thumb. U won't hurt anything by doubling that; in fact, lots of people are using either the BatCap or Alumipro's C.A.P. ( which is 15 farads ) on similiar sized amps to yours. As far as proximity to the amp, obviously the closer U can keep it the less the voltage drop will be but U can allow for this by using properly sized wire. I'd use the same sized wire on my caps as my power/ground wires. Personally, I try to stick with 18" rule of USAC/IASCA as it applies to your fuses; ie, my caps R within 18" of the amp they're on but I'm just Type "A"!! As far as surge caps, I'm not that familiar with those so I'll yield to someone elses experience there. If they apply to voltage surges within the system, then I'd say that U're right that higher is better.

 

The cap needs to be as close as possible to the load, if it can be less than 18", that's even better. What you're trying to do here is minimize the overall impedance of the circuit from cap to amp, such that it is also a much lower impedance than the circuit from battery to amp. That way, power for surges comes from the lowest impedance (the cap) and not from the battery. Otherwise, the further away you put the cap, and the higher the overall circuit impedance, the more useless the cap becomes. Especially when you're adding more than one cap (a good thing to do for extra instantaneous power), care is needed to not compromise the impedance of the cap circuit with too many connections, or poor connections, etc. The more wire you snake around, the less effective the cap becomes.
This is also why the caps have extremely low ESRs (equivalent series resistance) of thousandths of an ohm.

 

ok good, yea my caps shouldnt be more than 18''s away.
also is it hard to install a cap. ive done everything else myself, but im scared with caps. dont know exactly how to install it and the order of things etc. plus i only have one 4ga power wire then its run to a fused distribution block, then from the block, other things are powered, like tvs dvd, etc. so where does the cap go. (on the amp wire *after the distribtion block?)

 

Cap goes on the amp wire after the distribution block, no fuse between the cap and amp. Cap goes near bass amp if you have multiple amps. Cap must first be charged to battery voltage thru resistor, to prevent instantaneous inrush current when connected to battery. Follow directions that are provided with cap, charging resistor should be included as well. Don't short anything across the cap terminals when installing, it'll be like a wrench across a battery - fireworks.

 

Tim

 

Tim

 

Jimmy - If U've lost the resistor to charge the cap, U can also use a battery charger with adjustable output voltage. Craftsman makes one & I just start @ 3 VDC & slowly work my way up to 12+ VDC. As Tim & Eng said, don't just install the cap w/o precharging it as I have seen them explode from just such a move!:eek:

 

Oh my god!

Luckily, most car audio caps come with an "ooze" plug...I'd honestly hate to see a >= 1 farad cap explode!!!! Usually the plug just pops and all the innards ooze out...

A small light bulb really is a great option. You know its charged when the light goes out, and the filament provides enough resistance.

Tim

 

The only time I've ever seen a cap explode was with a small electronics project. Capacitor was rated at 35 volts and I had 50 volts going into it. Anyways the cap burst open shooting a 4 foot high stream of oil. Nasty smelling too. That's what you get as a first year electronics student. Read the labels!

This was only a 220 microfarad capacitor. Little guy about the size of a quarter. Don't go nuts with the 15 farad ones. Could possibly be deadly. Be careful!

Percy

 

And would that cap oil be PCB? Really nasty stuff it if is.

 

The cap oil is part of the insulator within the capacitor. Heck of an experiment!

Percy

 

or a test light i ended up doing that most of the time instead of dealing with the pesky little resistor that always ended up getting lost.....