Author Topic: Charging and discharging a battery / supercap  (Read 1610 times)

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Offline ivorasTopic starter

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Charging and discharging a battery / supercap
« on: April 28, 2016, 04:55:06 pm »
Hello!

Just for fun, I got a cheap 5V supercapacitor and a 5V solar cell, and I would like to power an Arduino through a DC-DC booster. I would like to do it in a way which allows the supercap to charge completely, then turns on the part of the circuit which discharges it, and that kind of seems like what battery chargers do. Basically, something which would have a hysteresis where it would charge the supercap to about 5V, then allow it to be discharged it until about 1V, then turns of the load while the supercap is charged again.

I have no experience with those at all, so I'm looking for some advice. Are battery charger controllers the modules I'm looking for? And generally, how to do this kind of thing with the most fun? :)
« Last Edit: April 28, 2016, 04:58:47 pm by ivoras »
 

Offline danadak

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Re: Charging and discharging a battery / supercap
« Reply #1 on: April 28, 2016, 11:36:11 pm »
Thats an easy problem for a low end embedded design.

Do you have ability to code microprocessors, or are you looking
for a finished module/board to do this ?

Regards, Dana.
Love Cypress PSOC, ATTiny, Bit Slice, OpAmps, Oscilloscopes, and Analog Gurus like Pease, Miller, Widlar, Dobkin, obsessed with being an engineer
 

Offline ivorasTopic starter

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Re: Charging and discharging a battery / supercap
« Reply #2 on: April 29, 2016, 01:16:36 pm »
Hi,

Coding is not a problem, that's my territory, I'm just new to the hardware side.

One possible solution I thought of (don't know how good is it) is to just do everything with software, e.g. put the MCU to sleep to conserve power (though I think it would still need around 3V to do that), and periodically wake it up, then measure the capacitor's voltage with analog inputs, and promptly go back to sleep if it's low. Since it's behind the booster, this could possibly work, though I imagine the power losses would be large while doing all this. And I don't know yet if Arduino can sleep for a specified time, or does it need an external interrupt to wake up.

I'd appreciate more knowledgeable advice :)
 

Offline danadak

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Re: Charging and discharging a battery / supercap
« Reply #3 on: April 29, 2016, 01:24:55 pm »
That would be the approach, and because you can do it at very
low duty cycle of active/sleep power consumption very low.

Here is an ap note that discusses this, much of it in a general sense.


http://www.cypress.com/file/121271/download



Regards, Dana.
Love Cypress PSOC, ATTiny, Bit Slice, OpAmps, Oscilloscopes, and Analog Gurus like Pease, Miller, Widlar, Dobkin, obsessed with being an engineer
 

Offline ivorasTopic starter

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Re: Charging and discharging a battery / supercap
« Reply #4 on: April 30, 2016, 10:40:53 am »
Hi,

Ok, if that is actually a usable way to do it.

For others' reference, here's an AVR/Arduino equivalent of the power modes discussion: http://www.rocketscream.com/blog/2011/07/04/lightweight-low-power-arduino-library/ and another one on the brown-out detector: http://www.avrfreaks.net/forum/should-i-use-brown-out-detection
« Last Edit: April 30, 2016, 10:42:51 am by ivoras »
 


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