[USB / DC / Solar Lithium Ion/Polymer charger - v1.0] Capacitor question

[niky89]

Hi,
can I replace the capacitor with another smaller or bigger one? Or, can I replace the capacitor with two or more capacitors in parallel?

[adafruit]

yes, as long as the voltage is 10V or higher and the combined capacitance is 4700uF or higher

[515]

Can I downsize the cap if I stick to strictly DC power? 1000uF or so?

[adafruit]

if you are not using solar, it is not needed

[Complicado]

If I wanna lengthen the LiPo battery lifetime by reducing the number of charge/discharge cycles, can I I replace the 4700uF/10V capacitor with a very large one like 1F/10V or even 10F/10V, so that the load would first drain the capacitor before discharging the LiPo battery, hence reducing the LiPo's charge/discharge cycles and increasing its lifetime?

[adafruit_support_bill]

No. That cap is on the input side of the charge controller. Not the output.

[Complicado]

No. That cap is on the input side of the charge controller. Not the output.

Yes, but could the load sharing feature cause this to happen:
1) Upon initial power-up, the solar panel input (Vcc) provides no power at all (due to light conditions), so the charge controller gets its input from the LiPo (Vbat) only, and load is powered by Vbat only.
2) After some time the solar panel provides enough power to power the load without having to use the LiPo, so charge controller switches to using Vcc only (i.e. the load sharing thing kicks in). At the same time, the capacitor is charged to full capacity (say very large, 10F or something).
3) It turns dark again and solar panel suddenly provides no power at all, but capacitor is still charged and still provides input to the charge controller, so charge controller continues to draw power from Vcc only.
4) When the capacitor is fully discharged, charge controller switches to drawing power from Vbat only.

[Complicado]

Separate question: the 4700uF/10V capacitor sticks out a little, and in some use cases could be prone to accidental damage. I wanna make the charger less accident-prone, by having a smaller, less obtrusive capacitor. What's the minimum capacitor size I can use without compromising too much on the solar output stability?

[adafruit]

the capacitor included is the minimum suggested

[Complicado]

Could the load sharing feature cause this to happen:
1) Upon initial power-up, the solar panel input (Vcc) provides no power at all (it is dark), so the charge controller gets its input from the LiPo (Vbat) only, and load is powered by Vbat only.
2) After some time the solar panel provides enough power to power the load without having to use the LiPo, so charge controller switches to using Vcc only (i.e. the load sharing thing kicks in). At the same time, the capacitor is charged to full capacity (say very large, 10F or something).
3) It turns dark again and solar panel suddenly provides no power at all, but capacitor is still charged and still provides input to the charge controller, so charge controller continues to draw power from Vcc only.
4) When the capacitor is fully discharged, charge controller switches to drawing power from Vbat only.

[adafruit]

the chip should automatically switch, however it sounds like you have a specfic project in mind that you'll need to build, test and debug
the design works as is, anything else you'll need to research on your own!

[Complicado]

I just think that if replacing the capacitor with a larger one helps to extend the lipo lifetime, this is a really neat feature that should be emphasised and advertised more. It could allow "perpetually powered" operation by extending the LiPo lifetime. This is particularly attractive for industrial use --- with hundreds/thousands of arduinos deployed --- since it results in less battery replacement, and lower operational costs.

This device, for example, uses a combination of supercapacitors and LiPo batteries to extend the LiPo lifetime, and it touts "Approximately 500,000 charge + discharge cycles " and "Exceptional long, self-powered life of 15-20 years "