Finally, today a little bag with some pogo-pins arrays arrived from China. Time to make my own USB charger for the tempest. Next step make a design to hold them and 3d print it.
To be continued.
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I have some of those around as well… bought them in '19 thinking of doing the same thing with the SKY…
never got around to actually making it…
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Next step, the basic design is done.
Four holes for the pogo pins, and a usb port in the part on the right hand side, and on the left hand side a small column that pushes the pins into place, and a part where I can slide the pcb with the usb port in.
Of course that is the theory. Experience tells me there is always something wrong 
(pins in wrong position, wrong height etc etc)
It isn’t supposed to be waterproof, just for some occasional indoor charging.
Also the printing process tends to make things a tiny bit bigger. Lets see and wait. I ran out of white material, so I’ll be printing in black.
Fingers crossed.
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So it can take either USB-A or micro-USB for input?
no, the pcb I used (because I happened to have it), is normally used to charge a lithium battery via the micro-usb, and the charged lithium battery is used to deliver 5V to the usb-A (a.k.a Power bank). In my 3d printed housing the usb-A port is covered up.
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That answered another question I had, the voltage of the output on the pogo pins. You don’t want to over voltage the input to the Tempest.
apparently the unit can accept 3-5V as a charging voltage (something I just learned today)
Wow - pretty nice looking.
About a thousand people likely want to know where to get the board and how long it takes to charge from dead to full, and how many Amps/Watts the charger part is, and the cost etc.
And I think it needs to shoot lasers up over the logo when it’s charging 
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the board is irrelevant, you could use any usb charger and use it’s 5V directly to make a connection to the pins. I just happened to have this little pcb and it was an easy way to get usb inside. I’m waiting for the unit to drop to 2.39V before I start charging. So I can’t tell. But you could of course just wait for weatherflow to release their powerbooster and see how useful that would be to you. For sure that one will be waterproof and perhaps it will shoot lasers as well
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Yes, just don’t go over 5V.
Yesterday, my tempest voltage finally dropped to 2.39V. Time to really test my charger. It worked great! It fully charged the unit in 11.5 hours.
There is a strange jump in the charging curve at 02:00. I don’t know why. Might be because I’m charging it via my tiny little charging circuit, instead of directly from the 5V usb power. (as a bit of extra caution, it drops the voltage a bit, and reduces the current.). I’m not going to investigate this, as in the end the unit just charged fine. (but it might charge a lot faster when attached directly to the 5V, I don’t know).
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Are you saying you can connect 5V directly to the Pogo Pins?
obviously not recemmended but you could connect 3.2 or 3.7V batteries?
Yes, you can directly connect 5V, that’s why I mentioned the board is irrelevant and it can use 5V directly.
"The tempest has a built in charge controller, just supply it with around 3v (3v to 5v is fine). It’ll current limit itself to around 400-500mA. "
Isn’t the jump associated with the fact that the battery is close to full capacity above 2.6 V, so the last little bit of charging happens very quickly and the voltage jumps up? I saw this on my Tempest when running on the solar panels today.
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not like this. Because it first flattens out at 2.6 volt before it starts the jump.
https://tempestwx.com/station/33745/graph/110506/battery/2
Interesting! I didn’t notice that plateau in your screenshot.
I could probably just reconnect my DIY so it uses the 5V instead. That might give way faster charging times, but I also like the little LEDs on the charging pcb that indicate if it is charging or full. And as mentioned, in the end it just charges fine, so I’ll leave it as is.
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If you’re taking it down anytime. any chance of measuring the voltage on all the 4 pins with the solar cells covered so no light is on the, and then again with light on?
I’d like to know if the charge voltage goes out through any of the 4 pins
If the charger is supplying voltage to any of the pins it would be great, because an accessory could be made with batteries in, that would not only keep it running in low sun but also charge them as well without having to use USB power
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