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Want to buy a cap but amp problem


Well-Known Member
June 28, 2003
Reaction score
City, State
ypsilanti, MI
Year, Model & Trim Level
94 ranger XLT
Ok I want to buy a cap cuz I have light dimming but I have 2 amps but only want to have one cap. Is this possible? I have a 200 watt mtx on the doors and soundstorm 700watt on the sub. Both wired indivually. Do I have to run yet another power wire under the carpet and to the back or does the cap just go into the amps power and then send power to the amp. Help please

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Im sure there is....

Do you have two sepereate power cables runnign to the back of the truck? or do you have One power cable, running to a spilter which divides it into power cables?

If you are running one power back, than the distribution box, you can put the Cap before the distribution. If YOu have it ran with two power cables running to the back, than you will have to wait for some one else to chime in, since i would not know the right way to wire it, i have an idea, but it doesnt seem like it would work.

Hope i did not confuse you.. if i did let me know and ill try and re-word it.


yes I ran 2 power cables back to the amps so that I know that they are getting the required power. Do I have to buy 2 caps cuz that will get pretty expensive. How much can I get a cap for that will run both amps. under $100?

Cut the power wire going to the sub amp - that is one you want to attach the cap to.

You do not need a cap for the door amp.

I was just looking in a crutchfeild magazine and they had a cap for $199. It was a 1000 watt 1fraud what ever that means and it said you could hook it up to two amps cuz it had a distrubution block built into it. Could I just buy like a $75 cap and put a distrubution block on it? How do I wire them does the cap go on the amps power line before the amp and then send power to the amps. If I get the $199 cap do I just only need 1 power line?

You do not need the cap w/ dist block, it is pointless for you,
What you want to do is take the power wire that goes to your sub amp, cut that wire and attach terminals to both end, both get attached to the same post on the capacitor and you also need a ground wire that goes from the - terminal on the cap to ground. Try to mount the cap as close to the amp as possible.

A one farad cap is what you want, what the cap is if you're listening to a song with some really heavy bass nots and the amp wants 60 amps and you only have 50 amps available then the cap can fill in and bring the power up for a bit.

do both amps really need an cap or just my sub amp? What is the best one I can get for the cheapest amount of money?

The cap is going to only be needed for your sub amp. Instead of spending 100 bucks on the cap have you upgraded your battery or alternator first? those will help out more than a cap will. A cap will only worsen your dimming problem if your battery and alternator are only stock.

Long Boring FYI about Capacitors

A capacitor stores electricity.. and is wired in parallel with your battery. The purpose of connecting it as close as possible to an amp is to minimize the voltage drop across a length of wire when the amp demands extra power. It is constantly being drained and filled up whenever your amp demands more power than the vehicle's electrical system can provide. Also, a long string of sustained high excursion midbass(70-90hz) hits will defeat your capacitor, as it will not get a chance to recharge in between.

A good rule of thumb is one farad of capacitance for every 1000 watts of RMS power that you have. There is no harm done by having too large of a capacitor, except the price. Best way to wire things when you're looking to use multiple amps and a high power setup is one zero gauge wire running back from the battery to your cap(s), amp(s) or any distribution blocks.

However, zero gauge wire is overkill for a < 1000W configuration, so if you don't plan on future upgrades a single 2 or 4 gauge wire would be plenty for the two amps you have.

As for your specific situation, if you connect one capacitor in parallel with one of your amps, both will benefit from the stabilizing effect it gives your electrical system, although your 200 watt amp won't see a major benefit as it doesn't draw a lot of power. If you haven't bought one yet, you can pick up a 5+ farad cap on EBay for about as much as you can get a 1 farad retail. No more lights dimming with those amps, ever.

Explorer94GV: 900 watts of combined amplifier power shouldn't be enough to put a huge strain on a stock explorer alternator.

Lets say its 1000 watts, to make it easier.. RMS power would be approx 500 watts. To get the current drain, divide the RMS watts by the voltage - lets say 14 volts. That equals 35.7 amps of current draw from the electrical system.

36 extra amps of current won't kill an SUV's alternator unless the battery is nearly 100% dead. It's a common misconception that adding a capacitor will worsen a light dimming problem, but that IS a misconception and only occurs when you have either of the following.

A: Not enough capacitance - bass hits, sucks power from the cap, cap empties, battery has to make up by both refilling the cap and producing the rest of the bass note. The 1 farad per 1KW rule of thumb generally eliminates that problem.

B: A bad battery or alternator.

Ok yall just confused me. I have upgraded my battery to a optma yellow top. I thought that would solve my problem but my lights still dimm and I can see my battery gauage bottom out when I am at a stop light and I don't even have the volume up much. It sounds like yall are sayin is that the cap will act like another amp and drain more power from my battery. What is the point of the cap then I thought it was suppost to prevent the light dimming. How long does it take to refill the cap?

The cap recharges very quickly - what it does is fill in if you are playing something that has a series of bass notes (bass notes draw a lot of current), so if you're sitting at a light the cap will be helping keep the power up then when you start driving again it will recharge.

BUT something else isn't right here, with an optima yellow top you shouldn't be having a problem.

ok I have thought about for a while and I have decided to dump the 2 wires going to the battery and get one big one comming form the battery and then split them into the 2 amps with a cap. I don't know which is better to do. Run the 2 amps in parallel along with the cap or have the 2 amps in series with eachother with the cap? I was leaning twords the parallel but I don't know.

02BLK_Limited: yes 900 watts is not going to burn out an alternator but you have to take in account also if you are running aux. lights, headlights, ac or heater, your hu, etc... that is going to draw some more amps also. bnicholas has a 93 Xplorer so im sure that alternator is the orignal being that you have a 02 Xplorer you wouldnt have a problem. bnicholas i say you put the $100 towards a new 200 amp altenator. If you have already upgraded the battery and still see dimming that is the next step. www.mralternator.com

yes that is exactily what I was thinking. I do have fogs on the battery too along with everything else. (heater, headlights, HU,........) I can't find no alt for $100. They are all like $225. Does auto zone sell high current alts?

Save your $$$$ No autozone does not sell 200 amp alternators but i do recall them having a 120 or 130 amp alternator for the "limited" explorers.

does any parts store sell the 200 amp alts??????

Originally posted by bnichols04
does any parts store sell the 200 amp alts??????

You gotta get em from a specialty shop, not a regular auto parts store. I got mine from


They are one of the more expensive companies, however I have receieved incredible customer service when i wanted to switch my alt casing from a 4.0 to a 5.0 engine, and the alternator is still working and I've been abusing it for probly near 4-5 years.

I'm sure others will have another shop that can get you a 200amp alt for cheaper

you might want to find out if a stock alternator from a later year will fit in your 1st gen. they beefed up the alternator in later years. if this is the original alternator its probably time to replace it anyway.

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If I buy a stock alt for my 93 will it survive the 900 watts I have or will I end up with the same problem in a few years?