DIY USB charger ready!

I’m not 100% sure what you mean with that. I think the two outer pins are connected to the solar panels (perhaps via a diode?). When I cover the solar panels up (and without my charger present) I just measured 0.32 V (I guess I didn’t fully cover them). I went outdoor and measured 2.71V but the sun was watery (I’m not sure if that is an English expression, but basically it was shining through a thin layer of clouds), so not super bright.

Of course my DIY charger is supplying power to the pins. how else would it charge?

Hi Sunny,
Just wondering if you would be willing to post a picture of your wiring so that we can have a go ourselves, that or a wiring diagram.
Anyway it’s a Great idea and thanks again for your help with the issue I had. :blush:

If there is no voltage when the solar is covered up then if you attach a charger to the outer pins it should charge the battery inside the tempest.
I was hoping that there might be power on the 2 inside pins at silver stage.
What I’d like to do is make a device similar to yours but with a battery inside that could be charged with the solar but also charge the battery inside the tempest as well.
I’ll try and draw a diagram of what I mean later when I’m home


Is this what you mean? You could just connect the wires to the usb port directly.
Seen from the bottom of the unit, the left most pin is power and the right most pin is gnd.

1 Like

Hi Sunny,
That’s exactly what I meant. :+1::+1:

O, I didn’t measure the two inside pins, only two outer pins. I think the two center ones are used to communicate (send data). My pokit pro (Pokit PRO | All-in-one multimeter, oscilloscope and logger by Pokit Innovations — Kickstarter) is being delayed, otherwise I might perhaps capture the signals.

That’s exactly what my charger does, power the outer pins, so it charges the battery inside the tempest.

If you want to extend the capacity of the battery, perhaps it is better to wait for weatherflow’s powerbooster, or just open the unit up and think of adding the same kind of battery that’s inside and connect it in parallel. There is room inside, not sure how to keep it water proof.
If you want to add an external charging battery, that battery has to be connected through some charging circuit. so the power has to be able to go into the charging unit when the sun is shining and come out of the charging circuit when the battery of the tempest is low. You have only two connections. I don’t know how to, but it might be obvious, just didn’t think about too much.

i could upload the 3d print files as well if you need them.

1 Like

Yes please, that would be great… :blush::+1::+1:

1 Like

what happened to your station that your voltage suddenly jumped from 2.41 to 2.73 in 2 minutes???

“If you want to extend the capacity of the battery, perhaps it is better to wait for weatherflow’s powerbooster”

That’s what I was curious about - is there any voltage on the 2 inner pins when the solar cells have sun?
I cannot see them making a powerbooster that didn’t have a charging circuit inside it and as most people have their tempest on poles that do not make them easy to take down to charge or run a cable to
I suspect there’s a way to supply the charging voltage FROM the tempest charging module through the 2 inner pins to a battery connected to the 2 outer pins
I cannot see everyone willing to send their tempests back to get them modified to do this and I cannot imagine Weatherflow wanting anyone to which is why I suspect that the 2 inner pins might have voltage when the solar cells have sunlight and are charging

I can tell you that their previous weather station, the Sky(and Air) ran on 8 batteries, and those lasted at least a year. If the tempest only uses power from the batteries in case the solar panels can’t handle it(a couple of weeks per year?), those batteries might last a very, very long time.

I don’t think I’m overstepping my bounds by saying this, but the two inner pins are TX and RX pins like @sunny said:

Ah
I suspect that means the external battery both charges itself and supplies voltage to the outer two pins, the Uart or spi communication tells the external battery pack to stop charging the internal tempest battery when it’s fully charged.

Thanks for figuring out how to charge this device. It was a brick for months this winter. I took another approach. I use a charged lipo battery. Thingiverse Weatherflow Tempest Emergency Charger by bsiege - Thingiverse

B.T.W I was a bit worried about turning the pins over the pads, therefore i omitted a rotating movement. I think this was not a perfect design from weatherflow, both mechanically and electrically.

I don’t know enough, but I do know that there is same voltage across the pins of the tempest when the sun is shining. I just don’t know if it is safe for your lipo battery. But I guess you won’t need it when the sun is shining :wink:

It is a protected 18650. But yes, i should add a disclaimer “i charge only during night” If i want to be careful, i could add a diode (low drop) And i do also not know what happens to the solar cells when charging this way.

actually that is what my unit does as well. I just put it on top and the weight pushes down on the pins. But that is by accident because apparently the design was a bit too tight (the 3d print tends to a expand a bit) and the slotting mechanism broke away.
But rotating should be save, as the top of the pins is much, much smaller than your drawing.

Ok here are my observations. The fact, that we had never enough sun this winter for charging at my location, i think the battery degraded massive. I simply compare the few days in november when i started to test the device and now after we had a couple of sunny days…

You can see that on the fresh device it works between 2.6V and 2.8V with a few more than 300W/M2 in november. Now in march we have much more sun power but it cannot even hold the voltage… Could be that the fact that most time in winter the battery was empty degraded the performance. And with this knowledge i understand, that the announced “PowerBooster” itself will not help for this constellation… Must have more Batterypower, AND more Solarpower. And for emergency a long cable :frowning:

How did you get that idea?