Capacitors/condensers are found in a variety of electronic devices and tools. This component stores excess electrical energy during power surges and releases it when the power is quiet to keep the device receiving a constant and even supply of electricity. Before handling electrical devices, you must first discharge the capacitor. Normally, the capacitor charge can be safely discharged using an insulated screwdriver. However, it would be better if you prepare a discharge device for devices that have large capacity capacitors, for example in various household appliances. Start by checking the charge on the capacitor, then choose a way to discharge it, if needed.
Step
Part 1 of 3: Checking the Payload
Step 1. Disconnect the capacitor from its power source
If it has not been disconnected from the device, make sure you have disconnected the power from the related device. Usually, you can simply unplug the device's power cord from the wall outlet or disconnect the car battery.
- For cars, locate the battery in the engine or trunk compartment, then loosen the bolts that secure the wires to the negative (-) and positive (+) terminals using an open end wrench or a ratchet wrench. Slide the cable off the terminal to disconnect it. Wrap the ends of each cable with a cloth so they don't touch anything.
- Inside the home, the device can usually be unplugged from the wall outlet; But if you can't, find a circuit breaker box and flip the switch that controls the flow of electricity into the room you're working in.
Step 2. Set the multimeter to the highest DC voltage setting
Different multimeters have different voltage ratings. Turn the dial in the center of the multimeter to the highest possible voltage setting.
Setting the multimeter to its highest setting will ensure that you get accurate measurement results no matter how much voltage is in the capacitor
Step 3. Touch the multimeter probe to the capacitor rod
Capacitors have two rods sticking out from the top. Simply touch the red lead from the multimeter to one bar, and touch the other lead (black) to the other. Hold the lead on the bar while you read the measurement results on the multimeter display.
- You may need to open the device or remove a component to gain access to the capacitor. Refer to the device manual if you can't find the capacitor.
- Touching both leads to the same rod will give inaccurate measurement results.
- You can touch red or black lead, as long as the stems are different. The multimeter measures the current flowing from one rod to another.
Step 4. Find the measurement result that exceeds 10 volts
Depending on the device being worked on, multimeters can display measurement results that range from single-digit voltages, to several hundred volts. In general, a charge exceeding 10 volts is considered dangerous enough to electrocute you.
- If the capacitor does not exceed 10 volts, you do not need to discharge it.
- If the charge on the capacitor is between 10 and 99 volts, remove it using a screwdriver.
- If the capacitor charges hundreds of volts, the safest way to remove it is to use a special tool instead of just a screwdriver.
Part 2 of 3: Unloading with a Screwdriver
Step 1. Make sure your hands don't touch the terminal
Charged capacitors are so dangerous that under no circumstances should you touch them. Never touch the capacitor other than the side of its body.
If you touch the two rods, or accidentally connect the two with a tool, you could be electrocuted or seriously burned
Step 2. Choose an insulated screwdriver
Insulated screwdrivers usually have a rubber or plastic handle, which prevents electricity from traveling from the metal part of the screwdriver to your hand. If you don't have this screwdriver, buy one that clearly states that the screwdriver is insulated. Some even tell the insulated voltage/voltage level.
- If you're still unsure whether the screwdriver is insulated or not, it's best to buy a new one.
- You can buy an insulated screwdriver at a hardware store, retail, or electrical store.
- The type of screwdriver head does not really matter, which must definitely be insulated.
Step 3. Check the screwdriver handle for signs of damage
Do not use a screwdriver whose plastic or rubber is cracked, broken, or torn. This defect allows electricity to travel from the metal of the screwdriver to your hand as it discharges the capacitor.
- Purchase a new insulated screwdriver if the handle of the old screwdriver is damaged.
- You don't need to throw away an old screwdriver with a broken handle, just don't use it to discharge capacitors and all other electrical work.
Step 4. Grasp the low capacitor by the base with one hand
You need to maintain complete control over the capacitor while it is being discharged so grab the capacitor low in its cylindrical body with your non-dominant hand. When lifted, make a "C" with your hands and fingers to grip it, and keep all fingers away from the rod at the top of the capacitor.
- Keep your grip comfortable. You don't need to grip the capacitor too hard.
- Try to keep a low grip on the capacitor so it doesn't get sparked when the charge is released.
- Use insulated pliers to secure the small capacitor so that it doesn't accidentally electrocute itself while discharging.
Step 5. Lay the screwdriver across both terminals
Hold the capacitor upright with the rod pointing at the ceiling, then take the screwdriver with the other hand and touch the rods together to release the charge.
- You will hear and see the release of electric charge in the form of sparks.
- Make sure the screwdriver touches both terminals at the same time; otherwise the charge will not loose.
Step 6. Touch again to make sure the charge has been released
Before you can get your hands on the capacitor, pull out a screwdriver and touch it back to the two capacitor bars to see if there's still a spark. When the charge is completely discharged, no more sparks should appear.
- This step is taken as a precaution.
- Once you make sure that the capacitor is completely discharged, the capacitor can be free to hold.
- You can also check that the capacitor is fully discharged using a multimeter, if you prefer.
Part 3 of 3: Making and Using a Capacitor Discharge Tool
Step 1. Purchase a 12 gauge wire, a 5 watt 20k OHM resistor and 2 alligator clips
The discharge device is really just a resistor and wire connected to the capacitor rod. You can buy all of these components at an electrical store.
- The alligator clip will make it easier for you to connect the device to the capacitor rod.
- You'll also need electrical tape or heat shrink plastic and a soldering iron if you don't already have one.
Step 2. Cut the cable in half 15 cm long
The cable length doesn't have to be exact, as long as there's enough left to connect the capacitors and resistors. Normally, 15 cm cable is sufficient, but you can choose according to your needs and situation.
- Each wire must be long enough to connect one end of the resistor and one end of the capacitor.
- Longer cables add more cable residue and make your job easier.
Step 3. Cut the insulator about 1 cm from each end of the cable
Use a wire stripper to remove the insulator without damaging the metal inside. If you don't have this tool, you can also use a knife or razor to cut the insulator, then use your fingers to pull it off the cable.
- Both ends of the cable is now the metal part.
- Make sure you remove enough insulator at each end of the cable to solder it to another cable or clip.
Step 4. Solder one end of each wire to the two probes sticking out of the resistor
Resistors have wire rods sticking out of each end. Wrap the end of the first wire onto one resistor rod and solder it together. Then, wrap one end of the other wire on the other rod of the resistor, then solder it.
- Now, the resistor appears to have long wires sticking out of each end.
- Leave the free ends of each cable for now.
Step 5. Wrap the soldered part with electrical tape or heat shrink plastic
Apply electrical tape to the soldered area to cover it. This helps keep the joint from coming loose while insulating anything that touches the soldered part. If you want to make a reusable tool, slide the plastic electrical heat shrink tube over the end of the cable and slide it over the soldered part.
- If you are using heat shrink plastic, you can attach it to the joint by exposing it to a lighter or candle.
- Do not expose electrical tape to fire.
Step 6. Solder alligator clips on each wire
Take the free end of the wire and solder it to the insulated alligator clip, then cover it with heat shrink plastic or electrical tape. Then, do the same on the other end of the free cable.
If you're going to use heat shrink plastic, remember to slide it on the wires before soldering the alligator clips; otherwise the plastic won't be able to get past the clip head once it's permanently attached to the cable
Step 7. Connect one alligator clip to each rod of the capacitor to discharge the charge
Attach the clips on the ends of the wires to the different terminals on the capacitor. The charge dissipates quickly, although you won't hear or see sparks like you would with a screwdriver.
- Make sure each clip has a clean connection to the metal rod.
- Be careful when working so that you do not touch the capacitor rods with your hands while connecting them.
Step 8. Use a multimeter to make sure the capacitor is discharged
Again set the multimeter to the highest voltage and touch the capacitor bars separately. If there is still voltage stored, check your discharger connection and try again. You can leave the multimeter connected to the capacitor so you can see the voltage drop directly.
- If the voltage does not drop, one of the connections in the discharge device is not working properly. Look for the damaged part carefully.
- After all the discharge tool connections are good, try again. Supposedly, now the charge can be released.
Tips
- Once the capacitor has been discharged, keep the leads connected to the resistor or wire to continue to discharge.
- Do not hold the resistor by hand; instead use lead or test wire.
- Capacitors will discharge on their own over time and most will discharge after a few days, as long as they are not powered from an external power source or internal battery. However, always assume the capacitor is on charge unless it has been confirmed that all charge has been removed.
Warning
- Always be careful when working with electricity
- Large capacitors are very dangerous and other people can also be affected by the work you do. It's best not to play with capacitors for just a hobby.
