Ultracapacitor to power electromagnet?

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    Electromagnet Power
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Discussion Overview

The discussion revolves around the feasibility of using ultracapacitors as a power source for an electromagnet, exploring various aspects such as charging methods, current calculations, and comparisons with batteries. Participants raise questions about the practical implications of using ultracapacitors versus traditional batteries.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant considers using ultracapacitors instead of AA batteries and questions the resistance and maximum current based on the ESR rating of the capacitors.
  • Concerns are raised about the energy density of ultracapacitors compared to batteries, suggesting that ultracapacitors may only provide a short duration of power.
  • Another participant suggests using batteries to charge the ultracapacitors and questions the limitations of AA batteries for the intended application.
  • Alternative battery types, such as SubC, C, or D size NiMH rechargeable batteries, are proposed for their greater capacity and current capability, with a caution against lithium batteries due to safety concerns.
  • Questions are posed about safely charging ultracapacitors from mains power and the potential dangers involved in using them.

Areas of Agreement / Disagreement

Participants express differing views on the suitability of ultracapacitors versus batteries, with some advocating for batteries due to energy density concerns while others explore the potential of ultracapacitors. The discussion remains unresolved regarding the best power source for the electromagnet.

Contextual Notes

There are unresolved questions about the charging methods for ultracapacitors, the implications of connecting them in series versus parallel, and the safety measures needed when working with high currents and voltages.

Who May Find This Useful

Individuals interested in power sources for electromagnets, those exploring energy storage solutions, and hobbyists working with capacitors and batteries in electrical projects may find this discussion relevant.

Pharrahnox
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I have been looking for a better way to power my electromagnet than a bunch of AA batteries, and am now thinking of using ultracapacitors.

I have a few questions.

I have been looking on ebay for them, I don't know of better options, and I have seen mostly 2.7V with >1F, up to 1500F. One in particular has grabbed my attention 10X 2.7V 10F ultracapacitors, for < $25, and they are stated to have: ESR (mΩ, 1KHz, 25℃) : 60

Does that mean that it has 60mΩ of resistance, therefore a maximum current of 2.7/0.06 = 45A?

What are the pros and cons of using capacitors as the power source for an electromagnet?

I think the resistance of my magnet is about 6-7Ω, so 2.7/6.5+0.06 = 0.41A. So I don't think the current would be too much, and I can always add more turns of wire (I have about 2500).

How could I connect the capacitors so that I can get more amperage? I know that connecting them in series adds their voltages, and decreases capacitance, but would that then also increase the resistance, rendering it useless?

Also, since the capacitors are rated at 2.7V, how do I charge them? I don't know of any 2.7V power sources... Also, is it possible to safely charge them off mains power, using a step down transformer?

Are there many dangers of what I am trying to do with these capacitors? If so, I would like to know, so I can prevent any injury or damage to myself or to the electrical circuits involved.

Thanks for any responses. Sorry about all the questions.
 
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You're probably best off sticking with batteries. Ultracapacitors still have much lower energy density than batteries, and you'll only get a couple seconds of use (or less) out of them before they die.
 
Pharrahnox said:
Also, since the capacitors are rated at 2.7V, how do I charge them? I don't know of any 2.7V power sources... Also, is it possible to safely charge them off mains power, using a step down transformer?
You could use batteries to charge them.

Where is the problem with AA batteries? If you need more short-term power, a capacitor in parallel to batteries could be interesting.
 
Perhaps use SubC, C or D size NiMh rechargable batteries? They will have greater capacity and higher current capability. Should be able to find chargers easily.

I hesitate to recommend Lithium rechargable for safety reasons. It's just too easy to burn your house down.
 

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