Open amcewen opened 2 years ago
Test conditions:
I think some of the varying behaviour is down to the charging chip trying to manage/monitor the battery. Hopefully some data-logging tests would give a better picture of that (particularly if we log performance on a bench supply).
It is possible to push 1.2A into the battery, at ~9V from the bench supply. At that point the chip is getting rather hot, and probably the mosfet is hotter. Think it'd be worth putting the FLIR camera on it if we repeat that experiment, and see just how hot it gets :grin:
Did a basic long-term test yesterday with the solar panel connected indoors but in full August sun in a South-facing window
I chopped board C in half to see if it was the caps on the rectified circuit which were causing the problem with it not charging from solar. Then when setting up a test I noticed that the solar panel had the polarity switched :facepalm: Correcting that resulted in the charging LED coming on as expected.
From the test, initially in bright South-facing sunlight:
Hi Adrian Thanks for the update - trying to get my sleep deprived brain around it.. does it mean that the board might be fine and it was the panel all along? Or were the capacitors causing a problem?
Thanks Laura
On Fri, 21 Oct 2022 at 10:21, Adrian McEwen @.***> wrote:
I chopped board C in half to see if it was the caps on the rectified circuit which were causing the problem with it not charging from solar. Then when setting up a test I noticed that the solar panel had the polarity switched 🤦 Correcting that resulted in the charging LED coming on as expected.
From the test, initially in bright South-facing sunlight:
- 10:00 - 3.8V. Solar panel was providing ~8V in circuit and ~110mA
- 13:00 - 3.83V. Had stopped charging as the panel was no longer in direct sunlight. However, when I checked the voltage across the panel it was ~4V, and checking it started it charging again. I didn't check the current then.
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Good question. Just done another very quick test, and it looks like the capacitors do affect things (and not in a good way). Taking it outside (on an overcast day) the one without the wind circuit and caps lit up the charging LED immediately, but I didn't manage to get it to light at all on a board with the wind circuit.
We should try removing the caps sometime, given the charger is expecting to cope with variable power from a solar panel it might also do okay with variable power from wind power. And I'll give the one with wind circuit another go sometime when it's really sunny, just out of interest.
Ahh ok thanks - great the solar part works :) If it ends up being separate boards for wind/solar then that’s not a problem.
On Fri, 21 Oct 2022 at 13:32, Adrian McEwen @.***> wrote:
Good question. Just done another very quick test, and it looks like the capacitors do affect things (and not in a good way). Taking it outside (on an overcast day) the one without the wind circuit and caps lit up the charging LED immediately, but I didn't manage to get it to light at all on a board with the wind circuit.
We should try removing the caps sometime, given the charger is expecting to cope with variable power from a solar panel it might also do okay with variable power from wind power. And I'll give the one with wind circuit another go sometime when it's really sunny, just out of interest.
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Need to charge my My Bike's Got LED battery today, so thought I'd test the USB charging.
The USB connector on board C doesn't seem to be soldered on properly—I'm not getting a voltage on the input connections. Have switched to one of the other boards instead.
Battery fully charged okay, and more quickly than the other charger I've got, which takes an age.
Tried the solar panel with the wind charging circuit again this morning.
The polarity is correct but I didn't get the charging LED from the solar. Plugging it into USB lights up the charging LED, so the circuit is working okay, and plugging the solar panel into the charging circuit that doesn't have the wind charging board attached also lights the charging LED, so there's enough solar energy.
I tried leaving it for a few minutes, but that didn't seem to make any difference. I think it'd be worth trying it with the wind circuit attached, but no capacitors on thatt—if that works with solar then we could see how well the wind charging circuit runs without the caps as maybe they aren't needed here (given that there's a charging circuit that handles variable input power and a battery to "smooth out" any variations...)
I've been using board A as a USB charger for my My Bike's Got LED battery for a few months now, and it seems to work just fine. As noted above, the chip gets fairly warm but has been working fine. We've used this circuit on v2 of the My Bike's Got LED boards and have included more copper around the chip to work as a heatsink. If that works better we can replicate it here.
One issue with the charger is that the "done" LED never comes on. The "charging" LED stays lit regardless. I've spun that out as #13 to see if we can work out what's causing that.
We have three boards soldered up: A, B, and C.
Results from some initial testing...