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Can I Replace a Capacitor with a Higher UF? (Explained)

You can find capacitors in almost all electrical and electronic devices. Whether it is your smartphone or washing machine or even the fan in your room, each of these has a capacitor.

If certain devices require more energy, you might want to replace the capacity with a higher rating. That is if it is possible to do so.

Can I replace a capacitor with a higher uF?

It is possible to replace a capacitor with a higher uF, particularly of a start capacitor. However, it is best to stay closest to the designated value and well within the tolerance of the capacitor. It is not advisable to replace a run capacitor with a much higher or lower uF.

Like a few other devices, it is possible to use a ceiling fan capacitor with a higher uF. You may want to remember that using a higher uF for a ceiling fan would change the speed of the fan.

Additionally, while you can use a Higher uF rating for ceiling fan capacitance, the other ratings should stay the same.

This would include, the capacitor having the exact specifications. When replacing with a higher uF, it is important to keep factors and ratings like voltage rating and wire number the same.

Using one for another is only possible under certain circumstances. Here are the two types:

Start capacitor:

As the name suggests, a start capacitor is used just when a motor is starting. Hence the energy or capacitance it has is much higher than a run capacitor. Start capacitors usually have a capacitance of about 70 to 120 uF.

If you want to replace the start capacitor, the uF capacitance of the new start capacitor can be about 20% higher than the one to be replaced.

While you can also replace the original start capacitor with the same rated capacitor, other ratings like the voltage must be kept the same.

Run capacitor:

Run capacitor is not on operation when the device is it used in just starts. Instead, run capacitors have lower uF and are used for continuous charging purposes.

Run capacitors can be about 7 to 9 uFs and it is crucial that the rating of run capacitors is exact.

Using a much lower run capacitor will affect the efficiency of the running motor, as will a higher rated run capacitor.

If you replace the run capacitor with a wrong rating is that any below 7uF or above 9uF, the efficiency and the performance of the device might decrease.

Can I replace a capacitor with a lower uF?

While replacing a capacitor with a higher uF is feasible, it is not recommended to replace a capacitor with a lower uF.

This would decrease the power consumption but the efficiency and performance of the device. If you replace the capacitor of a fan with a lower uF, for instance, it would lower the speed of the fan.

What happens if you replace capacitors with different values?

There are certain factors that rise with the higher and lower uF installation. Lets get to know them.

Using a higher rated capacitor:

Using a higher rated capacitor is possible if you are trying to replace a start capacitor. These capacitors are mainly used for momentary and immediate use.

Once a motor starts, a start capacitor completes its work. Hence when a higher rated capacitor is used, the tolerance of any capacitor must be kept in mind. If the 10 to 20 percent tolerance is not exceeded, the efficiency on the start would be quicker.

However, if more energy is drawn, the power consumption will increase. When any device consumes more power, the lifespan of the device decreased eventually.

Using a higher rated capacitor, particularly start capacitors, does not damage the device.  

Using a lower rated capacitor:

When a lower rated capacitor is used compared to how much is required, it means that the capacitor will be drawing and storing less energy. IN consequence, the lower rated capacitor will also release decreased energy to the device.

 For immediate effects, you would notice that the speed of the device is lowered. Other than that, the efficiency will also be diminished. In some cases, using a lower rated run capacitor makes the motor much noisier as well.

Additionally, an undeformed device might cause the motor to overheat, although the device’s power consumption will decrease.

Can I replace it?

There are multiple facts to consider while replacing a uF. Read below to know more about them.

Replace 5 capacitors with 6:

Capacitors can have a range of tolerance from -20% to +80%. However, most commonly, depending on what material capacitor it is, the capacitance will be 5% to 10%.

Hence with that tolerance, it is possible to replace 5 capacitors with 6.

Replace 5 capacitors with 7.5:

With the start capacitor, replacing a 5 with 7.5 capacitors is feasible, but not efficient. For a run capacitor, avoid using a 7.5 capacitor in place of 5.

Replace 6 capacitor with 7.5:

If your capacitor has a tolerance of more than 20%, you can replace the 7.5 capactior with a 6 capacitor.

You would not notice any difference, neither should it create any damage. However, if the tolerance is little, it is wise to use a capacitance value closest to 6.

Replace 5 capacitors with 10:

It is not advisable to replace a capacitor of 10 with that of 5 since most capacitors would not have so much tolerance.

 Without being burnt out or other physical damages, your power consumption will increase greatly.

Instead of increasing the efficiency, the motor would underperform and become heated up. However, there is little chance of damage.

Replace 4 capacitor with 5:

The tolerance of a capacitor is how much or how close the real capacitance can be to how much is designated.

Although negative tolerance is designated to many capacitors, running a device on lower capacitance makes your motor underperform.

Replace 45/5 capacitor with 50/5:

45/5 and 50/5 are dual run capacitor that uses the energy of two capacitors and combine them.

If the voltage rating on the two is the same, it is possible to replace a 45/5 with a higher 50/5 capacitor.

Replace 35/5 capacitor with 45/5:

The difference in a 35/5 capacitor is much wider compared to a 45/5 dual run capacitor.

Replacing one with the latter is possible but the efficiency of the higher dual capacitance would be inefficient and power consuming.

How to determine capacitor size?

If you have a slowing fan or faulty capacitor, it is important to be able to determine what capacitor size you can replace the older one with. Determining the capacitor size is simple.

At first, note the full load amps. Multiply that value with the number 2650. Next, you would need the supply voltage and note it down.

Divide the initial load amps multiplied value with supply volts. You can find both these numbers in the user manual of the device.

After multiplication, the number is the capacitor size of the capacitor in uF.

Is a higher uF capacitor better?

While all capacitors store energy by drawing the electrical power from the battery, all types are not the same. Each capacitor is made to release energy and this energy, also known as capacitance is measured in microfarads or uF.

There is no such science that a higher uF capacitance is better. While the effects are negligible, there would be no immediate damage to the device either.

A higher uF for a run capacitor is not a good idea. With an increase in power consumption and heating, higher uF run capacitor can increase motor heat as well.

Does capacitor increase fan speed?

Sometimes changing the capacitor can make a fan rotate faster. This is because increasing capacitance does increase the speed of the fan.

 As the capacitor with higher uF will draw and store more electrical energy, more power will be delivered to the motor. Hence increasing the speed.

When the start capacitor is what gives the fan an initial push or motion, increasing the size of the start capacitance will increase the initial motion speed of the fan. If the problem has to do with the blade or winding, increasing the capacitor value might not change the speed.

An increased fan speed does not mean an increase in overall efficiency.  

Does capacitor increase or decrease voltage?

A capacitor does not increase or decrease voltage or voltage rating. But the output voltage of a device and hence the performance of a motor can be altered with the help of a capacitor.

For instance, the arrangement of a capacitor is series instead of parallel will double the output voltage.

When replacing a capacitor with a higher or lower uF, the voltage should be kept constant.

Final thoughts

Using a higher or lower rated capacitor in your devices would mean that whether the efficiency or speed of the device is altered. Increasing the capacitance of a capacitor will increase the speed of the motor. However, the efficiency of the device might not be affected at all.