Ultracapacitor to power electromagnet?

[Pharrahnox]

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.

 

[cjl]

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.

 

[mfb]

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.

 

[CWatters]

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.

 

[sardar]

I would recommend conducting further research on ultracapacitors and their capabilities before using them to power an electromagnet. While they may seem like a more efficient and cost-effective option compared to AA batteries, it is important to understand the potential risks and limitations.

To answer your first question, yes, the ESR (equivalent series resistance) of 60mΩ means that the maximum current it can handle is 45A. However, it is important to keep in mind that this is the maximum current and it may not be sustainable for long periods of time.

There are several pros and cons to using capacitors as a power source for an electromagnet. Some pros include their high power density, fast charging and discharging capabilities, and long lifespan. However, some cons include their limited energy storage capacity and the need for special charging and discharging circuits.

To increase the amperage from your capacitors, you can connect them in parallel rather than in series. This will increase the current while maintaining the same voltage. However, it is important to consider the overall resistance of your circuit and make sure it can handle the increased current.

Charging ultracapacitors can be done with a dedicated charging circuit or through a step-down transformer from mains power. It is important to follow proper safety precautions when charging and discharging capacitors, as they can hold a large amount of energy and can be dangerous if not handled properly.

Overall, using ultracapacitors to power an electromagnet can be a viable option, but it is important to thoroughly research and understand their capabilities, limitations, and safety precautions before implementing them into your project.