Solar Panel Boe Bot need advise
Hi everyone,
I got my Boe Bot recently and I wanted to run the Boe Bot (BASIC Stamp 2) with solar panel instead of using battery.
Any advise of -
1) Do I get the solar panel with 6V or 9V?
2) How to connect the solar panel to the Board of Education from Boe Bot?
Thank you everyone.
Pang
I got my Boe Bot recently and I wanted to run the Boe Bot (BASIC Stamp 2) with solar panel instead of using battery.
Any advise of -
1) Do I get the solar panel with 6V or 9V?
2) How to connect the solar panel to the Board of Education from Boe Bot?
Thank you everyone.
Pang
Comments
So, my question now is "Can I connect the 9V solar panel to the battery with the reverse blocking diode to the Board of Education?"
I'm not the expert here, but I think you're going to find that your BoEbot requires much more current than the solar panel is capable of delivering. In fact,·one of the servos alone would exceed the panel's current capacity. Several of the panels wired in parallel would deliver more current, but·I never hear anyone doing it that way. In typical solar panel use, the panels are used to keep batteries charged, and the devices run from the batteries. Perhaps that's what you meant, but it sounds like you're hoping to just remove batteries and wire in the solar panels, and I think you're going to be disappointed in the results.
Perhaps one of the more knowledgeable folks could give a good explanation of why we don't just wire up a couple of the panels in parallel to increase the current, and run things off of that. In my limited understanding, that seems like it would work, but I'm pretty sure there's a good reason that I never see a project like that here.
Post Edited (sylvie369) : 7/21/2010 1:46:39 PM GMT
As Sylvie369 mentioned, when your BoeBot moves, it will draw much more current than the small solar panel can provide. You need the rechargable battery to act as a reservoir to average out the power drain. A Stamp that's running by itself draws only a few milliAmperes. The IR "headlights" draw tens of milliAmps. The IR detectors draw a few mA. The servos draw up to 1/2 A each when starting to move and maybe 1/4 A when moving freely. You can figure out the total average current needed and compare that to the average output of the solar cells to estimate how long the BoeBot can operate with solar power and under what conditions.
Post Edited (Mike Green) : 7/21/2010 1:41:43 PM GMT
I notice that the "evilmadscientist" page you linked to gives a pretty decent explanation of why you want something besides just a solar panel wired to your bot, and having read that,·I understand your second post better. I believe that the answer to your question is probably "yes, probably". It depends·to a great degree on what kind of batteries you're trying to use:
- Can they be charged by the solar panels in the kinds of conditions your bot will be in?
- When charged, will they deliver the voltage and current necessary to run your bot?
- What kind of capacity do they have? Will they run your bot for more than a minute or two before they need recharging?
I think that your next step is to get advice on batteries and the specifics of a charging circuit.
Thanks for the reply. I hope that you can understand my English.
In my case, the total current that Boe Bot can be drawn up to certain amount of current from the panel, so if I get maybe 2 solar panels (from parallax item code - 33001) total of 12V in an open-circuit voltage and connect in series instead of 1 solar panel, would the problem be solved?
Secondly, if assume that I figure out the suitable type the rechargeable batteries that I need to use, I can wire the solar panel (12V) with the batteries and blocking diode to the Board of Education, do I need to worry anything else?
Thanks again everyone.
Pang
Dave
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Dave Andreae
Parallax Tech Support
Thanks for the reply and the pictures. This is totally what I want to make. I kind of understand the concept of the solar bot. I am new to this field, so can you help me along with the circuit diagram because I worry that if I wire the wrong thing.
For the time being, I want to focus on the connecting solar panel to the batteries and board of education. I assumed that 4 solar panel 6V@1W are connected to the batteries, 47 farad super caps and photo resistor in series, is that correct? From the picture that I saw, I can't see where solar panels are connected to.
I would appreciate if you can help me along with this project.
Thanks again.
Pang
Thanks for the reply and the pictures. This is totally what I want to make. I kind of understand the concept of the solar bot. I am new to this field, so can you help me along with the circuit diagram because I worry that if I wire the wrong thing.
For the time being, I want to focus on the connecting solar panel to the batteries and board of education. I assumed that 4 solar panel 6V@1W are connected to the batteries, 47 farad super caps and photo resistor in series, is that correct? From the picture that I saw, I can't see where solar panels are connected to.
I would appreciate if you can help me along with this project.
Thanks again.
Pang
Dave
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Dave Andreae
Parallax Tech Support·
Does it run continuously while in the sunlight? Or does moving the bot eventually discharge the supercaps too much even when the bot is in the sun?
Does it need direct sunlight?
Is there some kind of charge controller for the supercaps? How are they simultaneously wired to be charged from the panels and to discharge to the bot's power rails? Are there additional parts? (I assume diodes, at least, right?).
Since Parallax suddenly has so many solar panels for sale, they should have some brief educational materials for these kinds of things. I can think of several topics offhand that would be very valuable.
I thought there were batteries. Anyway, i have drawn my thought of the circuit diagram in the attached file. I'm not sure if is connect to the Vdd or Vss or Vin?
Pang
Dave
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Dave Andreae
Parallax Tech Support·
Dave
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Dave Andreae
Parallax Tech Support·
1) They provide the short but higher power demands necessary to get the servos moving, and
2) They provide "emergency power".
The "emergency power" is used when the boebot isn't watching where he's going, and he finds himself in the shade. Now, a solar-powered robot with no sunlight isn't going very far - nowhere, in fact. The caps provide about 45 seconds of power - which is plenty of time and energy allowing him to retrace his steps (stop, turn-around, and get the heck out of Dodge, so to speak).
Batteries not included
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Matt Gilliland
I just want to show my understanding of solar Boe Bot so far. Please correct me if I am wrong.
1) In order to make the solar Boe Bot to move, I need to connect as like the circuit diagram where one end is connected to Vdd and another end is connected to Vss.
Pang
Right?
Dave
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Dave Andreae
Parallax Tech Support·
(I'm breathlessly waiting for you to set this up and hear how it works for you...)
Power management in solar projects is key, and is especially critical in non-grid tied applications - a solar powered (or charged) robot is an extreme case of the necessity of good power management. Dave's solar boe-bot has three servos (two on the drive-train, and a ping sensor too), not to mention the power required to run the BOE itself. Even with all these power needs, the little guy runs forever (in sunlight) and for quite a long time (in shade) because of the huge amount of energy storage capability in the super-caps.
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Matt Gilliland
I think I got the concept of it now. I will order the parts that I need soon and start on preparing the project.
I will update the progress as soon as I got my parts.
Thank again everyone for the helps.
Pangwu