What capacitor size or what electrical setup can store 115 to supply a motor for 1 minute or 40secs

Hello guys, it's my first time here and I really need help. I am working on a system that produces 115VDC. Can someone help me with the size of capacitor or electrical setup I need to store the said 115VDC to supply a 110 AC/DC electric motor for 1 minute or minimum of 40secs? Also, I'll appreciate if someone can direct me to a store that might have it for sale.



sort by: active | newest | oldest
You can't afford to do that with supercaps. Its beyond the state of the art.

To form a very rough estimate, estimate the energy the motor will use in one minute - current x voltage x 60 Joules.

Energy stored in a cap is 1/2 x C x V^2

As soon as you draw from the cap, the voltage falls linearly, so supercaps are nearly always used with power electronics to control the voltage, by stepping up the cap voltage.

Kourage (author)  steveastrouk4 years ago
Thank you Steveastrouk.
The rating of my motor is 1.45A at 110V.
According to the equation you have provided above, to run the motor for 1 minute would be: 1.45A X 110V X 60J = 9570.

Therefore, if Energy stored in a cap is 1/2 x C x V^2
(Using C = 30F i.e 30000000
1/2 X 30000000 X 110^2
15000000 X 12100 = 181500000000

Does seem to me this is too much. What do you think?
I think your maths is off a bit.

9570 is correct for the energy storage = 1/2 C V^2
9570x2 /110^2 gives C = 1.58 F. Your problem is that you can't get 110V capacitors, so you need to put 3V ones in series - 37 of them, with a value of 60F EACH.

Its going to cost a fortune.
Kourage (author)  steveastrouk4 years ago
Doesn't look like my project will be achievable using this method. Worse of it, I don't know what other way to get it done better.
Battery ?
Kourage (author)  steveastrouk4 years ago
Not a choice...
Why ?
Kourage (author)  steveastrouk4 years ago
Portability. And here, I already have the 115VDC from my module but it doesn't last for more than half a sec when supplied to the setup I am working on.

Also, the said setup is very delicate and need to use this voltage for only about 15 - 30secs and not more than 1 min to work properly. I know I could apply the timer module to turn it off. But how do I get it to supply my module for 30secs...That is the big problem I'm have now.

Regarding size, my setup is already big enough (24" x 24" x 18"). So adding batteries to it will make it too big.
Battery to store that much energy would be very small.
30, 30f, 3volt caps in series will run a 1amp 115v dc motor for more than40 seconds, with the right electronics.
What your looking for are Supper Capacitors. Go to any retailer like Mouser and see what they offer. You will need to use several of the same sized caps in series to get the output voltage you desire. Your best bet would probably be using 10x 12V super caps. You'll want to look through the data sheets on them to find the ones that could sustain the power needs of the motor for the time period you need. But you may have trouble tracking done any that could support your power needs for that time period.

http://www.mouser.com/Passive-Components/Capacitors/Supercapacitors-Ultracapacitors/_/N-5x76s?P=1z0x813&Keyword=super+cap&FS=True

You would be much better off using 12V batteries. 10 of your typical car batteries will be able to supply 120VDC to that motor for well over 1 minute.
Kourage (author)  mpilchfamily4 years ago
Thank you mpilchfamily.
Please refer to my response to Steveastrouk above and let me know what you think.

Thank you
Kourage (author)  Kourage4 years ago
"Below" I should have said.