Thread: Installing Power Capacitors?

how come nobody brought up the issue of rewinding an alternater? Doesn't a cap just add more stress to the alternator by having to charge up extra? If one was so worried about light dimming, why not just put out that money to go towards rewinding the alternator?

A cap might actually reduce stress on the alternator and battery by smoothing out ripples. Discharging the cap smoothes out voltage drops, and charging the cap smoothes out voltage rises. This could possibly extend the life of other components like your car electronics as they'll be subject to less voltage spikes and dips, but i don't think you need a 1F cap to do that..

But yeah, if your current needs exceed what your altenator can supply, you have to get a bigger one.. no way around that.

Also, no-one's touched on turning your volume down and saving your hearing That saves you even more money in the long run hehe

i bought one of those stinger red-top dry cell batteries, because i was interested in my lights not dimming so much with the bass, and having some reserve charge to keep my carputer in standby all day at work and all nite at home... it helped slightly but not nearly enough

recently i went ahead and got two rockford punch 1farad caps on ebay, one for $20 and one for $30, and while the light-dimming issue is very very minimal now, the whole system never has enough reserve to keep the carputer in standby, so that issue has gotten worse somehow (after installing the battery, but before the caps, the carputer would come out of standby fine overnite or after work almost every time...)

i suppose im posting for two reasons, 1) caps arnt useless, it seems caps and dry cell batts serve two rather different uses, 2) anyone have an idea as to why installing two 1 farad caps in my car audio system will drain any reserve in my 2nd battery? (if that is indeed the issue)

A properly used stiffening cap is to your electrical system, what your shock absorbers are to your suspension. You could drive your car without shock absorbers but the constant pounding will ruin structural components & transfer the shock to the rest of the vehicle. the stiffening cap will actually prolong the life of your alternator in the same way, by "absorbing" the big instantanious demands for high current & smoothing them out to a certain point. just because your caddy has shocks, doesn't mean you can go baja it off road, obviously a stiffening cap isn't going to cure all & if the overall average draw of the system & the rest of the vehicle is higher than the output of the alternator the cap will not solve your problem. you can't expect a stiffing cap to supliment a true 1000+ watt system, & even a bunch of batteries will only prolong the inevitable of draining your reserves, to run a system that has big power demands you must increase the output of the alternator to meet these demands.

the best solution is a combination of an aux battery close to the amps & a stiffening cap. A configuration like this will allow you to draw up to & even over your alternators output for short periods of time without a problem....

as far as idle drain,depending on the cap design, it can draw anything from a real small amount of current(.01-.02ma) up to enough to kill your battery in a several days. the best way to install a cap(s) is with a high current relay that disengages it from the battery while idle(parked). most carbon based caps are installed that way manditorily, as they will draw up to & over .06ma wich is enough to kill a battery overnight.

sdashiki, how old are you? I read somwhere that you're like 15 ...

If your lights are dimming, caps and batteries are only bandaid solutions. You need a higher output alternator to actually fix the problem.

Originally Posted by LittleDragon

If your lights are dimming, caps and batteries are only bandaid solutions. You need a higher output alternator to actually fix the problem.

this is not always the case. a stereo system, even a big one, will draw a fraction of it's total draw under normal conditions, & will only draw maximum under extreme hit's at full volume.

let's say your system draws around 25-30 amps at full volume unless there is a big bass hit, which can then drive it up to say as high as 100 amps at it's peak. now this is asuming your listening to normal music & not torture testing with like "bass 305" or something like that. let's assume your alternator puts out about 70 amps at idle . when these huge instantanious hits reach over the 70 amp's the lights dim for that instant. we can't forget that the car may need 10-30 amps alone, depending on what accessorys are being used at the time, headlights,wipers, a/c & even heater blowers all factor in, but let's say the car is using another 20 at night without rain, so the 30 + 20= 50 amps normal draw, with 70 amps available.

if a system like this has an auxilary battery & a cap, it will handle the bass hit's fine, & since the alternator is charging more percentage of the times than it is under, you will eliminate your dimming lights & basically be O.K., although a situation like this would be better if you increased the alternator for the times you are playing "bass 305" while driving at night in the rain with the ac on & the rear defroster to boot.

same sinareo, but with bigger amps that will give an average draw of 60 amps & peaks of 150 or more & you will see why this isn't always the answer...caps & an aux battery will only help if your average draw is under your average alt. output, & will help smooth out the peak demands for power, if your average draw is higher than your average output then you will experence voltage drop. this may be oversimplifying it a little bit, but that's really the jist of it...

I agree with turbo. I have a 150amp HO alt in my accord and my stereo still causes my lights to dim...a lot. But it just depends on the volume of the bass. Granted im pushing 1400 watts (real watts not hyped crap) but one would think that a new alt would fix it. It most certainly did not. If i am cranking on the stereo i swear it looks like im flashing someone. I also upgraded my battery to a Lightning audio deep cycle batter, it helped but jut another bandaide. I am looking into a BATCAP. Supposedly much better than a regular capacitor because of its long discharge rate at high amperage. A regular cap only farts high amps but then thats about it. Oh and im running a Memphis 16-MC1300D, (2) 12" JL w6v2s and dimond hex components all the way around. Just my 2 cents.

Originally Posted by LittleDragon

If your lights are dimming, caps and batteries are only bandaid solutions. You need a higher output alternator to actually fix the problem.

agreed. but when I get a papercut, I dont go to the hospital for a skin graft and surgery.

when peoples lights dim, they usually want to cure the *dimming*, not the *problem*

there isnt much evidence to suggest the *problem* is like smoking or eating McD every day, that is to say, a problem that leads to long term car health problems. I would even go so far as to say its not a real problem if you have to replace your battery every 4 years instead of 5 as a result of this *problem* (dont get me wrong, im not saying something like this WILL happen, I'm jsut throwing it out there qualitatively.)

however, if a cap will cure dimming, and if in its specific application it doesnt lead to short term battery draining (id say 50/50 chance that'll happen) then I submit that a $20 fix is WAY better than a $300 fix for headlight dimming!

I would like to draw another comparison. these stereo's we are all building take up lots of weight, right? why arent we all going out and upgrading our suspension? the weight we put in the back of the vehicle will lead to eventual fatigue problems with the struts of the vehicle. not to mention wear and tear of a motor that has to work harder to keep up compared to the stock car!

but we accpt these future issues readily; why such debate over the battery?

the human health parrallel in this situation is running the mile. I cant run a 6 minute mile, can you? so we know there are different *levels* of health, both for us and for our cars.

so for enjoyment of the stereo, we sacrifice a 6 minute mile for an 8 minute mile on the suspension and a 10 minute mile on the battery. is that worth spending $300 bones on a new alternator? for those out there who have new alternators and still feel justified after reading this, it definitely was worth it!

for the rest of us? no way.