Anybody use supercapacitor as battery?

[leu1]

My mini glider need very light battery. The super-cap which just need charge time of 10 to 20 sec maybe is the best chioce. But I do not know how long it can work under sevral 10mA. Is there anybody has experiences with that?

[richard tunstal]

the indoor and micro fraternity use these caps to power the drive motors (pager type)
of light weights.
gone out of fashion tho with arrival of lipos

[Miami Mike]

A good trick to obtain an ultra-small battery for a lightweight glider is to buy a 9 volt rechargeable battery and dissect it. They typically contain seven 150 MAH NiMh cells.

http://rsk.imageg.net/graphics/product_images/pRS1C-2160054w345.jpg

http://www.radioshack.com/product/index.jsp?productId=2062147&cp

[leu1]

Thanks for your advice, I will try it!

[vintage1]

use ultra small LIPOS rather..capacities down to 20mAh are there somewhere.

http://www.indoorflyer.co.uk/index.asp?function=DISPLAYPRODUCT&productid=178

[andrew b]

I have pulled down several 9volt cells, some have buttons inside and some have AAAA, but found all of them to be very low capacity/defective. They had probably been on a shelf for 5 years before I bought them :censored:

[Miami Mike]

use ultra small LIPOS rather..capacities down to 20mAh are there somewhere.

http://www.indoorflyer.co.uk/index.asp?function=DISPLAYPRODUCT&productid=178

That might be good for a miniature electric-powered model, but we're talking about a glider here. He needs 4.5 to 6 volts for his receiver and servos.

[z-matrix]

I have pulled down several 9volt cells, some have buttons inside and some have AAAA, but found all of them to be very low capacity/defective. They had probably been on a shelf for 5 years before I bought them :censored:

you probably got the cheapest brand and bought it at the wrong place,
i have a 8.4V nominal 250mAh rechargable battery, and i have no problems with it, though it was $10
charging at 22mA for 14 hours and its cool.

[andrew b]

you probably got the cheapest brand and bought it at the wrong place,
l.

Bought at the wrong place, I got slapped for about $13 for each one :(

[Acetronics]

My mini glider need very light battery. The super-cap which just need charge time of 10 to 20 sec maybe is the best chioce. But I do not know how long it can work under sevral 10mA. Is there anybody has experiences with that?

Internal resistance of supercaps is far too high for such purposes ... ;)

Alain

[vintage1]

That might be good for a miniature electric-powered model, but we're talking about a glider here. He needs 4.5 to 6 volts for his receiver and servos.

So use a pair and a teeny 5v regulator.

Capacitors have an awful sag as they discharge..and nowhere near enough capacity.

Rate of voltage drop in volts per second.. is current in mA divided by capacity in millifarads,

so e.g. a 10F capacitor at 50mA will be 5mV/second..200 seconds and its already down a volt..

These things are always heavier than a lipo pack and a regulator.

[leu1]

So use a pair and a teeny 5v regulator.

Capacitors have an awful sag as they discharge..and nowhere near enough capacity.

Rate of voltage drop in volts per second.. is current in mA divided by capacity in millifarads,

so e.g. a 10F capacitor at 50mA will be 5mV/second..200 seconds and its already down a volt..

These things are always heavier than a lipo pack and a regulator.

yes, that is what I worry about most! Is there any equations to caculate the discharge time? I had found some tools in MAXIM web site for RTC, but I do not know if it was accurate enough for my purpose :(

[Manchild]

A good trick to obtain an ultra-small battery for a lightweight glider is to buy a 9 volt rechargeable battery and dissect it. They typically contain seven 150 MAH NiMh cells. :



Why go through all the trouble when you can use lipos instead? LOL.

[LBMiller5]

Air Hogs make a little free-flight glider that has a capacitor inside as the power cell. It was something like a 10 volt 2200uF or some size close to that. You plug a charging unit into the motor pod and push a button to turn on the juice. The motor starts to run as the cap chargesd and eventually speeds up to a max RPM. At that point, the cap is fully charged, and you toss the plane. It runs for about 8-10 seconds until the power bleeds back down and then the plane glides down.

By brother got one as a Combo deal with a Air Hogs F-16 RC Plane. THe plane it came on flew like crap, but I salvaged off the power module and put it on a foamie plane made from BlueCor, and it flew pretty good! I can post a short video if anyone is interested.

Lucien

[vintage1]

yes, that is what I worry about most! Is there any equations to caculate the discharge time? I had found some tools in MAXIM web site for RTC, but I do not know if it was accurate enough for my purpose :(

You don't need tools.

dv/dt=I/C

Where t is seconds, I is amps and C is farads.

[Miami Mike]

Why go through all the trouble when you can use lipos instead? LOL.I'm glad to hear that I amused you.

LiPo cells would probably have to be hunted down and ordered through the mail rather than bought locally, plus he'd have to find the 5 volt regulator that Vintage1 mentioned and wire it into the circuit in such a way that it would regulate the voltage to his receiver and servos, yet could be bypassed to charge the battery. Of course, unlike a NiMh pack, if the LiPo cells were allowed to run down too far they would be destroyed and he'd have to start over again.

And I'm told that all that will avoid the "trouble" of opening a 9 volt rechargeable battery and taking out four of the cells, which will already be conveniently connected in series.

[vintage1]

It all depends on what is trouble and what is not..to you.

Certainly the worst regulation and smallest capacity per unit weight is a capacitor.

The lightest and smallest and best solution is LIPOS and a regulator..but it takes understanding what you are doing.

The SIMPLEST solution is to buy three teeny Nimh or Nicad cells and wire them yourself.

[Miami Mike]

The SIMPLEST solution is to buy three teeny Nimh or Nicad cells and wire them yourself.I'd use at least four cells, not three. If three NiMh cells were sufficient for your radio gear then you could use a single LiPo cell without a regulator instead.

[vintage1]

My mistake..but actually three IS probably enough..or one LIPO cell..must try it sometime.

Not sure if my charger can handle a single cell tho.