HELP! BEST WAY TO CHARGE SUPERCAPACITANCE TO LESS ENERY AS POSSIBLE? current source?

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mikaeltrigo

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Here is the situation:

I receive energy with a secondary coil ( 5-10V AC, 0,6A) only for a certain time. ( time that i can control) . I've to stock this energy with Ultra capacitor (10F, 2.5V or 5F, 2V). I will supply 2 motor 3V. I won't be charging my super cap when I'm using the motor. It's why i've to stock as much energy as possible ( the fastest way as well ).

My question is how i should i charge those Ultra capacitor ? I'm wondering If I'm losing to much energy by using a current source ! ( I've another voltage source to supply all my electronic components , i can't use it to charge my capacitor though)

thank you
 
Sorry but you need a capacitor with a higher voltage rating, you have a 3V motor so you need a 3V capacitor, ideally 3.3V.

More importantly:

How much current does the motor draw?

What's the minimum operating voltage?

And how long does it need to be powered from the capacitor for?
 
Sorry i made a mistake i can choose 2 different capacitor one is 5F 5V ans second one is 10F,2.5V.Maybe i can couple them to have approximatively 3.3V ?

I attached the characteristic of the motor.( i attached the capacitor as well).

The motor need to be powered as long as possible ( well I need to have enough energy to reach the next "charging place ").

But the real matter is how should i charge those capacitor. ANd if I've to use a current source which one would be the best ..

thank you
 

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The datasheet is in French which I don't speak.

The current drawn by the motor will depend on the load connected to the shaft.

You need to be more specific: exactly how long is as long as possible?

The maximum current rating of the capacitor in the datasheet you've posted is 1A.

Assuming it's charged to 3V and the motor stops working when the voltage drops to 2V, the capacitor will last for two seconds.

Sorry but I think using a capacitor to power a motor is a silly idea because you'd need a capacitor the size of a cola can to power a motor for more than a minute and it's very expensive.

You're far better off using a small battery.
 
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Actually i do not have choice to use that, I'm on a project and i will have to race with other teams..
here is the headline of the project
"An autonomous vehicle with a reserve of energy id stored in supercapacitors will
race against an identical vehicle on a track oval( the track 230cmX63cm). Two
stations placed along the route allow the vehicle to recharge the supercapacitors using
an inductive coupling. The vehicle overtaking his opponent is declared the winner. "

I'll use reducer as well with the motor.

I didn't find a datasheet in english aside this link
Data sheet for Coreless DC Micromotor -- 1724T003SR from MICROMO in Gearmotors on GlobalSpec

So depends on my strategy i will use moreandless the motor before recharging again.


Using this capacitor are the challenge ( how much, how to organize them???
 
It asks for a sign in so I couldn't get hold of that datasheet, can you post it as an attachment?

The key is maximising the energy extracted from the capacitor, for this you need to discharge it as much as possible so the motor you select will need to have a very wide operating voltage range.

You could probably overdrive the motor at a higher voltage for a short period of time so get a 5V capacitor if you can.
 
For maximum energy extraction and efficiency you could use a buck-boost switching regulator to power the motor. That would provide a constant voltage to the motor and efficiently use most of the energy in the cap.
 
The disadvantage is between 10% and 20% of the energy will be lost in the converter, not to mention the extra mass which will be a problem in a car.

You need to weigh up the advantage of being able to run down to near 0V and the cost of the energy loss and extra mass.

I don't know whether it's worth it myself.
 
Certainly there's a trade-off between the inefficiency and weight of an added converter, and the efficiency of the motor over a wide voltage range. If you can find a motor that will drive the vehicle over a wide voltage range with reasonable efficiency, then that would be preferable.

Since the 5F, 5V cap stores twice as much energy as the 10F, 2.5V cap, the 5F is the preferred choice for maximum energy storage. But if the motor maximum is 3V then you may need some sort of voltage converter or limiter for that. That is best determined by testing of the motor with the capacitors.

For charging the caps, a power supply set at the cap voltage with a current limit should give you a fastest charge.
 
Hi everyone.

I guess the extra mass off the car won't be a problem ! Since the second coil is on the top of the car, extra component will not even increase the total mass of 1%.

For the motor I've to use this one that's the rule ;-( I know i will have to use a converter

The other rules is that i can't use no more than 6 capacitors ! What would be the best arrangement to get the best out of it?

For charing caps i thought kinda the same way! Well since I've the input voltage is +- 5to10V, you think to set up the Tension at 5DC(straight it up) and charge the caps ( by limiting the current) is the fastest way?

Thank you for you help so far

I couldn't get the data sheet as well, i just have the french one..
 
I suppose you have to use the capacitors you've provided the datasheet for.

As I said above, you might be able to use the motor at higher voltages for short periods without damagine it.

If you go down the converter option, it might be better to use a higher voltage and use a buck converter because it will enable you to extract as much energy as possible from the capacitors. For example two strings of three in series would give you 15V which will keep your motor running until the voltage drops to 3V, assuming 1V of dropout and that the motor will work down to 2V.
 
Thanks that's gonna be really helpful.
i never use a buck converter before. But i will look it up in internet to unserstand it...
 
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