solor panel for charging rechargable batterys?

Rontopia · 2005-09-19 23:29

Hi all

I think this is my first post here.

I have a boe-bot with tank treads. on it i have ir and ping sensors and I am planing to put a tsl230 light sensor on it because im not happy with the photo resistors that came·with the kit.·my·goal is to have this bot roam and·"look" for the best light source it·can find. once found it basicly shuts down and charges the batterys through·a small solor panal for·period of time.. there are lots of details to work out.. but right now Im looking for a smallish solor panel. somthing that is 4x6 or so? little bigger is ok.

any ideas?

thanks for your time

·

Andy Lindsay (Parallax) · 2005-09-19 23:59

Muahdib,

That's a really cool project. I hope to see it in the Projects forum at some point.

I Googled “Solar Panel” and found lots of solar panel distributors. I noticed also that eBay has some pretty good deals on solar panels.

Experiments with Renewable Energy has some BASIC Stamp assisted solar battery recharging examples. The book is available for download from www.parallax.com -> Downloads -> Stamps in Class Tutorials.

One thing to keep in mind, the Boe-Bot battery pack depends on four 1.5 V alkaline batteries.· Nickel-cadmium (NiCad) and nickel-metal-hydride (NiMH) rechargeable batteries are 1.2 V per cell. It will take at least five of them in series to power a Boe-Bot.·

Andy

"Walk without rhythm..."

Post Edited (Andy Lindsay (Parallax)) : 9/20/2005 12:04:44 AM GMT

Rontopia · 2005-09-20 00:07

I have been running mine on 4 1.2 1800 mh bats..

form time to time the bot gets brown outs and I just replace..

could I use 8 1.2's with out harming anything?

·

Andy Lindsay (Parallax) · 2005-09-20 00:23

Hmmm, that's an interesting bit of news. Heck, keep using the four then...

Eight in series (9.6 V) is pretty close to the edge for the Boe-Bot's continuous rotation servos. If you protect them by moving the servo supply jumper from Vin to Vdd, the system will be less efficient because the regulator will be taking lots of current to maintain the 5 V supply.

A better way to use eight rechargeable batteries would be in two separate battery packs. One four cell pack to supply the BASIC Stamp (that will need to be recharged very infrequently), and the other to supply the servos. To make the two supply scheme work, you will have to unplug the servos from the X5 header on the Board of Education and wire them to the second supply on the breadboard. Make sure to connect the negative lead of this second battery-pack supply to Vss.·

Post Edited (Andy Lindsay (Parallax)) : 9/20/2005 12:52:26 AM GMT

SPENCE · 2005-09-20 00:51

I am not shouting. I have been able to read and type all caps much easier forover 50 years.

If i may suggest some research in homepower magazine. They are online and have many solar
panel sources. But be warned. There are a lot of ripoffs in the field. I have seen 5 and 10 watt panels selling for as much as some sell "good" 75 to 100 watt panels. I have been running a 60 watt panel now, for about 7 years and plan to add 2 120 watt panels within a year.

73
spence
k4kep

Tracy Allen · 2005-09-20 05:48

Thinking solar means thinking energy budget. Figure that a 4"x6" solar panel in full sun might provide 1 watt, say 200 milliamps of current at 5 volts at best. In artificial light, it will be much much less. For example, the same panel under bright artificial indoor light may produce only 1 or 2 milliamps. The energy budget will balance the current to operate the robot for a time with the time necessary to put that same energy back into the battery.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Tracy Allen
www.emesystems.com

Tronic (Greece) · 2005-09-20 09:56

Well, for indoor use there is a pretty simple solution. You can·turn a corner of a room into a feeding station by placing two 100watt lamps down near the floor (hanging at about 40cm from floor) so the robot can search for it using photosensors and then park under them.

Alternatively you can put a infrared activated switch to turn them off when not needed. When the robot needs to feed again it can trigger it on using its infrared leds...

I'm in the middle of building something simular with tank treads (bigger than parallax one's) using two 6v NIcd batteries hopping to make it charge entirely by it self. To handle all sensors, LCD, ADCs, inclinometer, servos·and power transistors I was forced to use two BS2 connected like master-slave...

The thing hanging in the side is the analog inclinometer!!

P.S. I Liked Dune too!

Post Edited (Tronic (Greece)) : 9/20/2005 10:28:22 AM GMT

Rontopia · 2005-09-20 16:00

thanks.. not many people catch the dune connection.. most think im from iran or something..

anyway.. why did you have to go to 2 boards? did you run out of i/o's

I like your bot and the Ideas you have.. where did you get the treads? and do you have problems with them coming off on carpet?

the only thing that I want to do differently is that I want mine to be able to " maintain on its own" without any human interaction. that is why I want to add a clock and be able to "shut down' and "startup" on its own. I also will have two run levels to conserve batterys. I may be adding another servo to mount ping and light sensors on so that the whole bot does not have to actually look around to find light, just the sensor array.

where did you get your panel? and what kind of a charging circuit are you using? is one of your micro controlers controling the circuit or is it always on?

sorry so many questions[noparse]:)[/noparse]

Muahdib

FlyingFishFinger · 2005-09-20 22:33

Hey, I could do with some tracks like that,too. I was looking for ones off the Kyosho Nitro Blizzard, but they're very expensive and slightly too large.
Rafael

N-2-STUFF · 2005-09-21 04:36

check out www.solarbotics.com for solar cells.

scott

Tronic (Greece) · 2005-09-21 08:02

Thats right, I run out of free IO's and programming space. Plus I wanted to gain some speed so it doesn't have to stop moving the servos to go thru all sensor scanning + LCD update + ADC readings all the time.
I got the treads ripped from a toy that I bought from a local toy store for 10 euro!
I immediatelly discarded the body and the DC motors it had and mounted the gear wheels on hitec continous rotation servo.
Of course I had to construct my own body to fix the rest of wheels and the servo from computer junk (HDD holder, front panel mountings etc)
It doen't stuck nowhere and it has enouph power to climb a wall with result to fall on its back. Thats the reason I added a inclinometer (simple 10k pot with a weight on its axis) to prevent it from damage. Due summer I took it on the beach where it was tested on sand succesfully...!
Well, I also want it to be able to maintain it self but in the place of a timer I was thinking to having it activated (trigger the payload mission) by human presence (sense movement).
I'm currently having three modes: full power, Low power(slowly searching light) and charging state (which hold still and shutdown)
The charging circuit is controlled by the slave bs2 and its simple. It consists from some Power transistors and a NE555 ADC based circuit to monitor both battery and solar panel voltage. I have a page where it is shown but its in greek:
http://users.sch.gr/xrysoxoidou/user_projects/Analog_to_Digital_NE555/analog_to_digital_NE555.htm
I suppose you can figure it out since it has its variables named in english and it exists in english form (google it).
The panel I found is not very efficient and I ordered new smaller ones from solarbotics which I'll install soon. My plan is to get more than 200mAh to get the batteries fully charged in less time.
The project is in continuous revision to find the most effective design, so I might redesign the Bs2's and the rest electronics in a sigle board to gain some more free space and make it lighter.

Any questions are welcome!
·

Chris Savage · 2005-09-21 14:37

Tronic,

·· In order to overcome sensor overload where I have a lot of sensors going and it seems to be interfereing with servo refresh updates I use counters within the refresh loop to trigger the sensors every so many servo pulses.· If you have a lot of sensors and you stagger them, then it really smooths things out.

DO
  counter = counter + 1
  IF counter = 10 THEN
    GOSUB Ir_Detect
  ELSEIF counter = 20 THEN
    GOSUB Ping_Detect
  ENDIF
  
  ' Act Here On Sensor Results
 
  GOSUB Go_Fwd
LOOP
 
END
 
Ir_Detect:
  ' Your code here
  RETURN
 
Ping_Detect:
  ' Your code here
  counter = 0
  RETURN

And this is an example...You would of course have to tweak things and such, but I am using something similar on a BOE Bot that needs to scan using a PING))) sensors as it's moving forward.· Originally doing this slowed the BOE-Bot down considerably, especially when there was nothing in rnange of the PING))), but now it pulses every 10 or 20 servo pulses and goes full speed again.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com

solor panel for charging rechargable batterys?

Comments