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 Author Topic: New VP2 Project  (Read 1020 times) 0 Members and 1 Guest are viewing this topic.
ADJ2
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Posts: 9

 « on: March 14, 2010, 10:00:49 PM »

How long would it take to charge 2 - 50F 2.7v super caps on a VP2 ISS wireless board.

I have the caps installed and have 2 solar panels wired in series (no load voltage is 5.53v), connected to the ISS
voltage reads 0.47v.

No sensors are connected.

After 24 hours of continuous charging, the voltage on the caps have gone from 0.0 to 1.69.

One conclusion so far from this and reading other posts here, is a voltage regulator is a part of the operation of
the board.(3v battery, 2.7v cap and the 2.24v output of the Davis solar cells.)

As someone once said, "When searching for answers, you only bring up more questions".

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dalecoy
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 « Reply #1 on: March 14, 2010, 11:14:02 PM »

How long would it take to charge 2 - 50F 2.7v super caps on a VP2 ISS wireless board.

I have the caps installed and have 2 solar panels wired in series (no load voltage is 5.53v), connected to the ISS
voltage reads 0.47v.

Well, let's see.
Are the supercaps wired in series or in parallel?
What is the maximum current output of the solar panels?  [And are they receiving rated sunlight 24 hours per day?]
What is the internal resistance of the solar panels?  Is there additional current-limiting resistance in series with the supercaps?
You said no sensors, but the ISS is on and transmitting?  If so, how much current is it drawing?
The above info, or equivalent, is needed to actually try to calculate an answer to your question.

Voltage reads 0.47v - measured where?

After 24 hours of continuous charging, the voltage on the caps have gone from 0.0 to 1.69.

Engineering approximation: about 36 hours of continuous charging.
 « Last Edit: March 14, 2010, 11:16:23 PM by dalecoy » Logged
ADJ2
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Posts: 9

 « Reply #2 on: March 19, 2010, 11:01:18 PM »

So much for being rhetorical.

As one can see from the picture no sensors are connected, it's laying on my kitchen table.
Super caps are wired in parallel as Davis designed the board.
Max. out put of solar panels was stated as 5.53 volts.
Rated sunlight? (on my table? No). Florescent light.

Quote
What is the internal resistance of the solar panels?  Is there additional current-limiting resistance in series with the supercaps?
Davis does not let that info out.

Quote
You said no sensors, but the ISS is on and transmitting?  If so, how much current is it drawing?
Davis does not let that info out.

Quote
Voltage reads 0.47v - measured where?
Across the terminals on the solar panel while connected to the ISS.

Quote
Engineering approximation: about 36 hours of continuous charging.
So much for engineers, at 88 hours I was at 2.87 volts.
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dalecoy
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Posts: 3478

 « Reply #3 on: March 20, 2010, 09:51:00 AM »

OK, so I didn't understand that the picture was of your actual test setup, or that you were illuminating with your kitchen light.  Are you using the Davis solar panels?

In any case, whatever illumination you have is clearly insufficient to reach the rated output of the solar panels - and now that you say the voltage reading is across the solar panels, they are obviously current-limited, and as you said they aren't producing their rated voltage (because of that).  In fact, you could easily calculate the internal resistance of the solar panels if you actually had them in bright sunlight.

The other values would be easy to measure.

But - bottom line - you say this is a new project.  What are you actually trying to do?  I'm fairly sure it isn't to find out "How long would it take to charge 2 - 50F 2.7v super caps on a VP2 ISS wireless board." from zero charge while the ISS is in the kitchen.

Perhaps I can give a more helpful response, if I know the objective.
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