how do i charge a capacitor?

ocool_15

Member
2004-11-26 3:15 am
sk
charge

1.2F will draw big current, normally they come with a little charging thing. If you want to charge it in house get a normal 12V adapter(make sure if its unregulated the voltage isnt going past its rating) and you need a series resistor try something about 1.2K ohm to 2.2K and it will probably take a minute or 2. notice it will discharge itself when not in use.
I believe my rockford 1F is 16V and 20V surge
 
You can't just connect the cap straight to your amplifier/fuse block/ distribution block. these caps normally come discharged (0 volts) and will suck a HUGE amount of amps for a short while when they charge up. this will cause huge sparks (like touching jumper cables together!) and blow a fuse. You need to have a resistor or a car light bulb connected between the positive input of the soundsystem and the battery. I have had luck with connecting the capacitor as usual, and inserting the resistor between the main feed from the battery and the rest of the audio chain (such as removing the main fuse and sticking in the resistor, or connecting the resistor between the battery and the wire to the audio system when i go to connect it to the battey. just be sure not to short anything while in there.)

If you are suing a resistor, you will also need a voltmeter and the resistor needs to be at least several watts. I have used a 8 ohm, 20 watt dummy load/speaker crossover resistor with good luck (just because I had it). the more ohms, the slower it will charge. I wouldn't use anything much smaller than 10 ohms. stuff over 100 ohms might take quite a while. The meter will be used to tell you when it's done. you can either connect it accross the resistor to show how much more voltage you need to go. will start at around 12 and work it's way down to zero. you can also connect it from the cap positive to ground (starts at around 0 and goes up) and see when the voltage on the cap is very close to the battery voltage. Note that the charging is NOT linear, it will asympotically approach full charge, this means that the voltage will change fast at first, and then get slower and slower as it gets closer and closer to being full. Theoretically, it will only get reeely close but never exactly there. I prefer the method of connecting the meter accross the charging resistor. hat way I know it's done when the voltage is very close to 0 (under .1 volt) and changing very slowly. I will usually then measure the voltage from the cap positive to ground to make sure it's 12V and then connect the cap in and call it a day.

use the lightbulb just like the resistor, it will light up bright at first, and then get dimmer. once it goes out, wait a little bit and then you're done. You cna use any kind of 12 volt bulb. small interior lighting and brake light bulbs are popular.

Just be very very careful with the cap once it is charged, you do NOT want to short it out, it can deliver HUGE amounts of current. treat a charged capacitor much like a car battery - DON'T SHORT!
if you remove your main fuse at the battery, your system will still be powered for some time since the capacitor will hol a charge. if you want to "safe" it, you can either turn the system on and let the amps drain the power, or use the lightbulb/resistor accross the capacitor this time (cap positive to ground), with the meter to assure that there is no voltage on the system at this point

Also note that the vehicle's electrical system will still be powered for a while off of the cap when you remove the battery (don't let the car's terminals short to each other when the battery's out, or you'dd short the cap and make sparks/blow fuses). I recommend leving a door open or something when taking out the car bettery with a "capped system" - the car's interior lights should drain the cap to a coupla volts in a little bit, and provide visual feedback in the process. remember to go through the "charging" procedure again when you put a new battery in the car.
 
if you just connect the capacitor w/o first charging it up, it'll make a huge SPARK and blow a fuse every time, and possibly damage something. tis will happen every time the capacitor is connected to a "live" system, or when you first connect the power to a system that you have just insalled.
 
dr.p, you are full of knowledge, thanks! lemme ask one more thing. once the cap is charged, i will disconnect it and put it in its proper mounting place, what is the procedure for hooking it up to the amp (reconnecting it)? power cable intput first, power output to amp second, and ground last?

and do you think the small bulb that came in my kit is the resistor?
 

sc0rnypoo

Member
2007-03-26 5:01 am
plz help

i just bought this system from my cousin.. Infiniti 1500watt amp... 2 12" mtx thunder 7500 (sludgehammer box) and a 2 farad tsunmi capcitor....but he dosent remeber if he discharged before i took it.. and after completeing the hook up and driving around i stoped to get gas and the car wouldnt start afterwards.. never happend before.. so i was basically woundering if i have to recharge the capictor or what. and if so how do i recharge it cuz ive never done it.
thanks
 

Oatface

Member
2010-08-18 10:24 pm
Power Cap

I recently hooked up a 30 farad Boss capacitor and I never charged it, but connected it straight to the battey right away. There were some sparks, but after it got a solid connection it was fine, no fuses blown, no damage done to anything and it all runs great fully charged.
 
yah, the little bulb worked great, i'm charged and ready to go! thanks all.

My inner evil monster is wondering if the little glass bulb looked like this:
 

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Personally anytime I have installed a cap in a system for someone I trip the circuit breaker or pull the fuse on the main power wire then hook up the cap in the system completely and mount it where its going,then reset the breaker or put in the fuse back in the fuse holder and screw back together and the cap charges, never had a spark and never blown a fuse or damaged anything.