4-Post Lift Start Capacitor Blew Up...

[brentmc]

I was lifting my car and the lift got to about 1 foot from the ground when I heard a very loud "POP" and the factory smoke came out of capacitor.

The bottom of the capacitor blew into pieces.

How do I test to find out what happened?

Would a capacitor that is failing or failed blow up like that?

It is an Eagle 8K 4-post lift.

Thanks
Brent

 

[RPH]

Capacitors die, usually spectacularly.
It may have dried out and fell out of tolerance. I would order replacement one up. I would go with a higher voltage rating while doing it.

 

[brentmc]

Thanks--It is 16 years old and has sit in a hot/cold garage for its lifetime. I didn't know if it was likely that something other than age caused it to blow.

Higher voltage would be higher than 300VaC, correct?

 

[u3b3rg33k]

ahem, a start cap shouldn't be in-circuit for a whole foot of movement. it should only be "on" until the motor is spun up. check your centrifugal switch.

but you showed us a failed run cap, so that's not what happened. cap prob just gave up on life. if you spectacularly fail a second one in short order, you've got something else to worry about.

 

[brentmc]

Should I check something in the motor before swapping capacitors or just swap it out and see what happens?

 

[The Cobbler]

caps die like that . very likely nothing else wrong.just put in a new one & call it done as far as voltage, yes , you can go higher. just don't go lower

 

[brentmc]

higher would be higher than 300vac--correct?

 

[RPH]

this would work. Anything high voltage over the 300 vac indicated is to your long term happiness. 15 years ain’t bad, sorry to inform you it died of old age.

 

[pattenp]

this would work. Anything high voltage over the 300 vac indicated is to your long term happiness. 15 years ain’t bad, sorry to inform you it died of old age.

He doesn't need a dual cap.

 

[Worsedog]

While the above would work, you don't need the extra terminal. Additionally, it's much larger than the original and won't fit under the cover.

 

[brentmc]

While the above would work, you don't need the extra terminal. Additionally, it's much larger than the original and won't fit under the cover.

Roger that--I really appreciate the recommendation though--GJ folks are awesome! I do need a smaller one and am stumbling through Amazon now to find one

 

[The Cobbler]

here's one https://www.ebay.com/itm/1220226000...UxP5uxAOKOa+cTHn44UeryRc8N|tkp:Bk9SR7yc-eSuYw

 

[RPH]

He doesn't need a dual cap.

True but it was the first to pop up. Plenty of choices in the wild. It doesn’t hurt him either.

 

[micromind]

higher would be higher than 300vac--correct?

Yes, 300 would be ok, the next step up is usually 370 and next is 440.

Usually, the higher the voltage, the larger physical size.

If the life acted and sounded normal, it's most likely that the cap was simply at the end of its life.

Start caps are designed to be in the circuit for a short time. If the centrifugal switch failed, it'll usually take nearly a minute for them to blow. The motor will usually growl too and quite often the overload will trip before the cap blows.

 

[u3b3rg33k]

300vis fine for a 120V nominal (170V P-P) application. higher voltage often means more insulation which often means thicker which means a bigger diameter capacitor. if it fit under the cover I wouldn't be afraid of a dual cap if the price is right.

 

[OccupantRJ]

Roger that--I really appreciate the recommendation though--GJ folks are awesome! I do need a smaller one and am stumbling through Amazon now to find one

I get mine from the local electric motor shop as cheap as I can buy it on Amazon, and can have it in a few minutes.

 

[brentmc]

Thanks gents. Two more dumb questions.

I bought this one; it has three terminals—which two do I use?

Also, do I absolutely have to have a cover? My original cover is too small now.

Thanks again

 

[rooster59]

.

 

[brentmc]

I heard pvc pipe would work okay too

 

[micromind]

Thanks gents. Two more dumb questions.

I bought this one; it has three terminals—which two do I use?

Also, do I absolutely have to have a cover? My original cover is too small now.

Thanks again

One of them will be common. One of the wires goes here, doesn't matter which one.

Another terminal will have a mfd rating. The 3rd terminal will have a different mfd rating. The other wire goes on whichever terminal is closest to what the original one was.

The 3rd terminal is not connected.

 

[OccupantRJ]

Do either of the mfd ratings match or exceed your original capacitor?

 

[dogdog]

Just get a direct replacement so it fits in the cover. Make sure it is a run capacitor type and not a start cap rated. You don’t need higher voltages, offers no benefits. Same is fine. You need it to fit under the cover so next time when it pops you don’t soil your ******* or undies. At least it is all contained under the cover.

 

[dave*99]

https://www.amazon.com/uxcell-Capacitor-Cylinder-123x60mm-Compressor/dp/B098S9J496/?tag=atomicindus08-20

 

[pattenp]

Thanks gents. Two more dumb questions.

I bought this one; it has three terminals—which two do I use?

Also, do I absolutely have to have a cover? My original cover is too small now.

Thanks again

It's too big because it's a dual cap for running two motors such as a fan and compressor in an A/C unit. You should have gotten a direct replacement one that fits.

 

[mm08822]

One of them will be common. One of the wires goes here, doesn't matter which one.

Another terminal will have a mfd rating. The 3rd terminal will have a different mfd rating. The other wire goes on whichever terminal is closest to what the original one was.

The 3rd terminal is not connected.

The pic shows "Herm" and "Fan". The 3rd one will be "C" for common. (Herm = Compressor)
Connections to Herm and C will give the higher mfd rating.

 

[wyliesdiesels]

ahem, a start cap shouldn't be in-circuit for a whole foot of movement. it should only be "on" until the motor is spun up. check your centrifugal switch.

but you showed us a failed run cap, so that's not what happened. cap prob just gave up on life. if you spectacularly fail a second one in short order, you've got something else to worry about.

ummm the cap is labeled as a run capacitor.

 

[RPH]

For reference on peak to peak voltages, one reason I stated stepping up on voltage ratings.

“ Is 120v peak to peak or RMS?


For AC from the wall, the rms voltage is approximately 120 V, and the average voltage is about 110 V. The peak voltage, then, is actually 120/0.707 = 170 V. This is half the amplitude of the sinusoid. The overall amplitude, which is called the peak-to-peak voltage (Vp-p), is twice the peak voltage, or 340 V. “

 

[u3b3rg33k]

ummm the cap is labeled as a run capacitor.

not in the thread name tho. I'll be sure to remind OP.

 

[brentmc]

Thank you gentlemen. I’m a little unclear on parts of this. Here is what I think I am reading;

Th capacitor I bought will work but has an extra terminal and is a dual cap.

I can hook one wire to herm or fan and the other to “C” and it will work okay.

The capacitor should fit in a cover so that if it blows again, there will be a shield

Before I hook this up today, can you confirm I’m on track?

I mostly just need to use lift for a few minutes to get one car up for storage. I then have a couple of months to get the perfect capacitor.

Many thanks!

 

[dave*99]

Use Herm and C. Do not use Fan.

 

[dogdog]

The cap should work

Yes use C and Herm, C to the electrical supply side like L1 or L2 and herm to the motor winding side. And tape up the fan terminal as it will also be energized when power is supply to the C terminal. You really don’t want an open terminal that is energized accessible. But that is my take on this.

Yes it should be in a cover just in case it blew especially in cold temp, I have had smaller electrolytic cap blew with a huge bang from mother boards that I power up from cold temp. Loud and pants might or might not have been soiled. So I would get a cover. Unless you are Rambo and go commando. Then no worries.

 

[RPH]

I had a buddy when repairing boards who had a tendency to install polarized capacitors backwards. You knew it happened when the 12 gauge cap went boom, confetti flying, him saying fu**!
Went that way for thirty years.

 

[wyliesdiesels]

As said above use the herm terminal. The fan cap is only 5ufd