Xanthorrhoea wrote:... change in model (colour) by Fastech, I'd held out until last week, and just as I gave up it finally arrived. I've been charging a few devices to see what it can do....
I'm curious, which panel did you get?
The one that I mentioned, and Mark F and others refer to in this thread is this one with the red arrow in my collection of various panels from a pic taken last year.
- Solar Panels.jpg (82.54 KiB) Viewed 21370 times
The reason I ask is that Fasttech stopped stocking that 6.5W panel sometime last year. I checked around November 2019 and the SKU was taken off their site, replaced with a different model.
There is one that is $10.41 (SKU 9708339 -
https://www.fasttech.com/p/9708339), that looks similar to a panel that I also have (in the picture, to the left of the panel with the red arrow is the panel with the built-in "handle"). But the solar panels used and the controller box appears to be different to the one I have. So there's a good chance the performance of mine would not match the one that you've got.
- Is that the one you ordered?
There are a quite a few 6.5W panels floating around Fasttech and Aliexpress, that have come from the failed share Limebikes. These panels are reputedly quite hardy (designed to sit at the bottom of the handlebar basket of the Lime sharebikes), but were designed to output 12V. Some resellers have installed their own 5V output controllers and these panels are being currently sold like
http://www.aliexpress.com/item/33024560385.html I haven't tested these yet though.
I did pick up a similar panel from Fasttech, and only received it about 2 weeks ago (SKU9726595 -
https://www.fasttech.com/p/9726595)
It looks ok, but I was disappointed that mine came with very poor gluing to the USB output controller. There was barely a dab of glue holding the controller to the board, and the soldered leads were the only thing holding the USB controller in place.
- SKU9726595 badly glued.jpg (100.83 KiB) Viewed 21370 times
I use various USB meters to check the output of my solar panels - these are basically in-line USB ammeters.
- USB Meters.jpg (202.46 KiB) Viewed 21370 times
For example, these are some of my meters. The very basic ones like these "USB Charger Doctor" only display the Voltage and Amperes when the solar panel has sunlight. I would manually record the maximum Amps and the charging duration, but this wouldn't be the most accurate as it would stop when the sun was under cloud cover, and I didn't monitor the charge every second.
The other meters I have in my toolkit have the ability to display the cumulative mAh passed through. However, not all these are great with solar panels. These USB meters do not have built in power supplies to run the screen, and "borrow" power from the source - in this case the solar panel. While the amount of current it uses isn't much at all, but in some cases, I think that using with solar panels might have some issues.
For example, the black one (Keweisi MX18) with the lovely colour oLED display screen displays the cumulative mAh (and Wh) and the time taken to charge as well as the Voltage and Amps, and the temperature. However, to my dismay I found out the memory is destructive when used with a solar panel, and would reset once the solar panel is obscured and input power is cut. This isn't meant to happen as it has 10 memory slots and using USB power (either a powerbank or wall socket), if the power is cut, it stops and when power reconnected, it continues the recording from the time the power is cut. I haven't quite worked out why it resets the memory count on Solar Panel, potentially due to the voltage dropping to a certain level, but that makes it not useful to test my panels in the field.
The silver/blue Keweisi KWS-V20 meter shows the cumulative charge in mAh, and does work as intended to record the solar panel output, even when the solar input is interrupted. It is about 4-5 years old though, and has a few issues now.
I have a few other fancier and more expensive meters, like the rather pricey yzxStudio zy1280 meter, and the cheaper Ruideng UM34C. I did something stupid with my zy1280 meter and it no longer functions.
The UM34C (yellow meter in the picture) is great and displays a great deal of information, but the memory also destructive when the power is cut. I got this tester as it has both a USB C and micro USB input, and I thought I could externally power the USB meter with a smaller battery bank when plugged into the solar panel, so that when the sun was obscured, the tester meter wouldn't reset. But alas the USB C and micro USB inputs are to test the resistance to USB C / micro USB cables, and not to power the unit.
The UM34C has a great Bluetooth function where I can log the results in a spreadsheet on a phone or a PC, but again, when the sun cuts out, the meter resets and the bluetooth connection is severed. If I don't manually reconnect, it doesn't record the data to my phone, even when the sun is no longer obscured.
So, long and short of it, while I can do tests on the panels in a controlled environment like the back yard on a sunny day, and I will take this as the maximum output the panel can achieve. In practice in field use, strapping it to the pack in non-optimal angles to the sun, and walking under tree cover, in shade of mountains or clouds, it can be 50%-80% of the amount taken under my controlled test.
On bad days like walking entirely under tree cover, or in valleys, of course you will get zero power from the panel.