I got a lot of comments that many of you discharge run capacitors with a volt meter. I test this method vs. the capacitor discharge tool I created.
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All right, so this video is in response to a lot of people who said that they use their meter for discharging a capacitor instead of my crazy little capacitor discharge or tool that I made so we're gon na see I've charged this capacitor. This is a turbo mini and I've charged the 5 micro farad portion of it and charged with 120 volts, and so we're gon na see how long it takes to discharge with a meter. Because the theory is, you know, the meter has a resistance to it and impedance to the meter, and so the meter can act as a discharging device. So, let's see what we get here, so we're gon na go actually, let's, let's, let's keep our black on the common there, so we're gon na go common and then our 5 micro farad all right so 150, volts, 1.
2. 3. 4. 5.
6. 7. 8. 9.
10, you get the point, a problem with the meter, isn't that it doesn't tell you whether or not as charge or not it. Just it's not really effective at discharging it in a timely fashion. So is it? Does the meter work yeah? The meter works because it's gon na tell you if it's charged and they're usually not charged, so that method is totally fine. You get your meter on you, then you can use your meter to see if it's charged and if it is charged, then you can use a capacitor discharge.
Er, like I've got here in order to discharges. So let's do my test now and I'll show you you get the 5 micro farad here. I know some of your gon na be like innocent yourself. He'll be fine! I'm shocked myself with worse than that, all right.
So then we just take this and place it here and I'm just gon na do it for a little say: 2 seconds: 1. 2. Okay, now we're gon na see if we still have any voltage applied - and I haven't tested this before so. If we or not nope no voltage we're almost, I mean no.
No in this become alright, so there we go. If you actually want to discharge a capacitor then use a capacitor discharge. If you just want to test and see, if you have voltage that a meter works just fine and if you want it to take forever to discharge, then you can just wait there for like half an hour until exactly till it finally discharges through your meter. Hopefully, that's helpful, we'll talk to you next time.
couldn't you switch it to ohm meter and dischrge it through the meter?
If you did this with a 2000 v microwave capacitor your multimeter fuse would blow, correct?
"Oh, I'll be fine!"
– famous last words 😉
What percentage of capacitors you check will actually have a voltage and why do some not ?
I think your 2 seconds was closer to 3 seconds.
Love the video. What gauge wire should I use for the cap discharging tool?
You discharged 40V in 10 seconds with a multimeter. At that rate, you will fully discharge the capacitor in 40 seconds, not the "half hour" you mention.
Hello Bryan would it be possible to upload a video on how you made your personal discharge tool?
Thank you for making this video. I had to replace the run capacitor in my AC. Didn't have a discharge tool so I figured the multimeter was better than arching screwdriver. The capacitor was totally uncharged but I am thankful I had this option ! Service area Barrhaven??
It really is not a race. Do it right because an ounce of prevention is worth more than a pound of cure. It's your right to do it your way, but why teach beginners how to do it wrong? I know I don't have the brass to dead short a 7 farad cap. Yes they can get very large. All the best to you sir.
What about the tongue method?
I'm surprised you didn't share a link to your DIY capacitor discharge tool. Are you in Orleans ?
Set the meter on A/C or D/C volts?
The time constant for capacitor discharge/charge is capacitance x resistance. With the rule of thumb, 5 time constants for essentially fully charged/discharged. Assuming some extremes, a 100 mfd capacitor @ 450 v. The time constant with a 20k ohm resistor is 2 s, 5x=10s. 450v on a 20k resistor = 22.5 mA. Not bad, that is an initial power discharge of 10 watts.
Makes perfect sense! And no, I don't think I want to use a screwdriver. That might be OK for lower powered DC devices, though. (I do think that's how I messed up a circuit on a bass distortion pedal once… long story!)
I found you today through watching you with MATT. I trust Matt and he trusts you, so I am a new subscriber. I have now watched several of your videos and I have a few questions. It just so happens that one of our daughters is having a new system installed this week and also my parents are having an issue or two. So without a lot of explanation, here are my questions.
Starting with my parents ACHV system. We live in the Tampa Bay area, so hot and humid most of the year. We also have hurricanes and sometimes need alternative power. My father recently bought a portable generator that maxes at 7500 Watts surge. 6000 Watts normal run. He'd like to be able to run the house AC (WITHOUT HEAT), in times of long power outages. He's got a 3.5 ton unit that is 16 seer. I don't remember the brand. I think he could run his AC ONLY if the generator can handle the surge. NOT being a tech or even an electrician, I believe I understand that the capacitor is to give the fan and compressor motors a jolt to start up. His system has a cap on it from the factory, but I don't understand why we do not use a second cap for this surge/boost? Is it feasible? Can a second cap be added to reduce the pull or surge on the incoming power?
I'd also like your opinion on using UV LIGHT to kill and keep mold from growing?
Last Q. Is it true that the air handler and the indoor and outdoor units cannot be mixed as they use to be? My daughters air handler is pretty well plugged and in a inside closet. Very difficult to work on and the entire unit must be removed to pull the fan. She got an estimate and asked what it would cost to put in a new air handler that COULD BE serviced. She was told it is no longer legal to mix units. I realize they would have to be compatible, but that sounds like BS to me. Please advise on all. I truly appreciate it!!
you could also use a diode as well.
Check out grayfurnacemans video on this subject.
Or just short it with a screwdriver. Service area Kanata??
🤔 a new day for a lot of people.
Great job Bryan! Thanks! You made a believer out of me. And this with only 5 MFD. Imagine 40 or 50 MFD.
Added: I stand corrected. This video is a perfect example of how old dogs can learn, correctly, what they thought they already knew.
If your digital meter has a LoZ or Low Impedance mode the cap discharge in a LoZ voltage mode will be quick. Normally a high impedance digital meter loads a circuit with an equivalent impedance of ~10 megohm where a low impedance mode, when available, is typically a 3k to 100k ohm load.