Charging Capacitors?
Printed From: the12volt.com
Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=18213
Printed Date: June 05, 2024 at 10:57 PM
Topic: Charging Capacitors?
Posted By: italnpimp59
Subject: Charging Capacitors?
Date Posted: August 28, 2003 at 8:07 PM
hey i have always heard about having to charge a capacitor beofre installing it. although i have installed alot of car audio and security...i have only installed two caps...they were used and i installed them in my truck. i have heard they have to be hooked up to the battery with a 32ohm resistor on the positive lead. i am an installer at a shop here and i asked the other installer who works with me and he said he has heard that too but he just hooks them up and they work fine. could someone please explain to me what the deal is with charging them up and how/when it is needed? thanks
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Replies:
Posted By: xetmes
Date Posted: August 28, 2003 at 8:23 PM
The resistance is not really all that important. The reason for using a current limiting resistor is to limit the current it will first draw. When a drained cap is hooked up it acts like a dead short drawing a great deal of current, with a resistor, the lowest impedence it can first have is that value of the resistor (in DC). You probably could just go about hooking them up like that but i really dont like the idea, the higher the capacitance the slower it will charge, therefore it will draw short-like current longer.
Posted By: defective
Date Posted: September 02, 2003 at 7:40 AM
Hey, here you go: Hook the cap to ground in the vehicle or better yet a bench 12volt supply. Attatch the power wire to one end of a light tester, connect the other end of the light tester to your 12volt on the cap. When the light goes out, your charged..... if you leave it for too long after this and don't install immediately, you'll have to charge it again. BTW: if you charge it in the vehicle, make sure the engine is running to get the most power...... Also: when you don't charge a cap and install it, it does absolutely nothing, it just slows power response. So CHARGE IT!
Posted By: italnpimp59
Date Posted: September 02, 2003 at 5:56 PM
we have a bench 12volt supply at the shop but i think it only puts out like 5A of current...does that matter? if i cant use that then would it work to ground the cap to the vehicle and attach the positive to the battery in the vehicle? when you say light tester..do you mean a test light? ground the alligator clamp to ground and put the probe on the 12volt on the cap and when the light goes out, the cap is charged? how long does that usually take? thanks for the help.
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Posted By: defective
Date Posted: September 03, 2003 at 8:38 AM
that bench tester should work fine.... and no..... connect the cap to ground and put a test light between the 12v and the + on the cap........ The light tester should be inline on the power, doing it the way you suggested is how t discharge the cap. this is great when your selling or not installing for a while, but put the light tester in line on the power to charge.....the light will come on and then slowly fade out until it's out....then disconnect and install. Hope this helps...good luck.... and keep it clean
Posted By: italnpimp59
Date Posted: September 03, 2003 at 8:25 PM
so ground the negative terminal(or attach it to negative of the bench tester) and use the test light like this : probe the positive wire coming from the bench tester and put the clamp from the test light on the positive end of the cap? how would the light come on like that...shouldnt it need power and ground to turn the light on? im confused with this...but i really wanna know how to do it, thanks for all your help so far...maybe you could clarify that so im not confused anymore...thanks in advance!
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Posted By: Switch
Date Posted: September 03, 2003 at 9:25 PM
i install my cap were ever i so choose to install it.(in the trunk) the cap will be fused under the hood so i take my test light alligator clip to + post of batt and lead side of test light to fuse holder and charge that way untill light goes out. it takes about or less then a min. to charge. and to discharge i just do the same but i put alligator clip to - post of batt untill light goes out . all your doing is pulling power from the batt and putting it in the cap and the other way around when discharging. i would never myself install a cap already charged nor whould i take a cap out with it still charged. now of course all of this depends on the cap that you are installing some caps do charge themselves.normally the caps that have led's charge themselves were as caps that do not need to be charged
Posted By: audiodesign
Date Posted: September 03, 2003 at 10:17 PM
you know when you check for a 12 volt draw you would usually do it on the negative terminal just do it the same way but to the positive terminal until the light goes out.
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