View Full Version : yep, capacitors are worthless

blue LEDz
12-12-2003, 01:01 AM
so i was trying to see if using a diode to isolate a capacitor to each headlight would actually work, and while it does work, it doesn't work for long:( i used a 1/2 farad capacitor and with my crude testing, it showed to be about .5 farad. it dropped about 7 volts in half a second with about an 7.5 amp load. but that means it dropped from 15.82 volts to around 9 volts with only a 100 watt H3 halogen bulb hooked to it. current draw averaged at 7.5 amps. so i'll guestimate that at 1/4 of a second the voltage had already dropped to below 12.8 volts, where normal car batteries run at. and that was only with 100 watts. so the whole 1 farad per 1000 watts is total crap. 1 farad by my test would have lasted 1/2 a second to drop below 12.8 volts. now divide .5 by 10. that means that a 1 farad cap would keep the voltage up above a regular battery for UNDER .05 seconds:rolleyes: i wish i had real test equipment, but i make do with what i've got:biggrin: course here's the kicker, i tested out my batcap 300 also. i just hooked it up without checking the voltage. after over a minute of the bright ass light blinding me i disconnected it. i charged it back up, and actually checked it this time. it dropped about 1.47 volts in 15 seconds. it went from 11.92 to 10.45 volts. and i figured the amperage to be about 9 amps, since the voltage was lower than with the cap, but i may be mistaken with my logic for that. anyways, by that calculation the batcap is equal to about 92 farads. BUT that's in a lower voltage area. i couldn't get the batcap over 12 volts. i'm going to test it tomorrow in my car, but if it doesn't run over 12 volts on it's own, it's worthless:mad: also, once it hit 15 seconds for testing, every 15 seconds following the first the voltage dropped .2 volts each time. that's where the battery properties come out. the capacitor went completely dead, while the batcap kept putting out juice, even if it was at a low voltage.

to recap: capacitors are worthless. batcaps's could possibly be worthless, unless mine is just dying:(

12-12-2003, 08:45 AM
blue LEDz,

Thanks for the interesting research you carried out. When you first came up with the idea of combining a diode and a cap to prevent headlight dimming, it sounded like a great idea to me and I really thought it would work based on theoretical considerations. As your results indicate, unfortunately it doesn't. Just another example of something that sounds good on paper not working out in practice. At least you saved some of us from spending money on something that doesn't work.

In regard to your test with the Batcap, I was a little unclear as to how you carried it out. Did you just hook up the Batcap to the H3 bulb directly or did you also have the diode/cap in the circuit? Since this test was made outside the car it will be interesting to see if there is any improvement when you connect it to your car's electrical system. Keep us posted.

blue LEDz
12-12-2003, 11:05 AM
yep, the batcap was hooked directly to the H3 with some alligator clips:biggrin: i didn't bother with the diode, since i just wanted to know how long the cap or batcap would last;) the voltage drop over the diode was .3 volts, BTW. that i did test:biggrin: *if* it were economically sound to either get a small fast recharge battery or a decent sized cap, the .3 voltage drop won't matter for much on the brightness of the bulb, as long as it keeps it constant for longer than without the cap;)

12-12-2003, 05:17 PM
Nice experimenting. Caps = waste of money.

12-13-2003, 03:29 AM
nice info blue, you need to get paid for this

blue LEDz
12-13-2003, 10:54 AM
Originally posted by walight01
nice info blue, you need to get paid for this

naw, i'll get paid when i sell dumb kids capacitors for thier systems:biggrin: my buddy is planning on opening his shop in early summer;) and if he doesn't, the manager of another shop in town is going to open his own shop next year sometime. he was looking to buy out the shop he's worked at for 12 years, but it's not busy enough, and not the best location. i was talking to him the other day when i brought in my SPL meter, and he was telling me his plans, and where he wants to open it. he's got the best location picked out, cause it's in an area with a TON of business, but they all have to drive 20 miles away for the nearest shop. and if he opens his own shop, he wants me to work there definintely:p: