Author Topic: tested ebay solar cell panels  (Read 4979 times)

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picmacmillan

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tested ebay solar cell panels
« on: February 26, 2005, 07:33:40 PM »
i hooked up 3 of my homemade ebay solar panels to see what they would produce for power...i had read some folks didn't think they could produce, and to be honest, i wasn't too sure myself....below is some photo's of 3 of the panels...i hooked the first 2 in parallel and the last one in series,...when i hook up the rest, i will put them in series also to increase the amperage below are 2 pictures of the volt meter...i got 3.4 to 3.6 amps and 14.4 to 15.2 volts for these 3 panels ...so, i guess they are working....i did notice some condensation inside one of the panels, but not all 3...so i thought that was a little strange as all of them were built the same....i have some dessicant silicon that i am going to insert on the inside of these panels to see if that stops the condensation...one more thing,...the panel on the far right is made up of broken and chipped cells...so it still works even though it is not as good as the rest...i do understand that they should all be the same strength but for this experiment they worked just fine in parallel...anyhow, thats if for now.........pickster







« Last Edit: February 26, 2005, 07:33:40 PM by (unknown) »

jimovonz

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Re: tested ebay solar cell panels
« Reply #1 on: February 26, 2005, 01:31:56 PM »
Great job! I only wish freight charges to NZ were more reasonable! Dessicant silicon is not a long term solution as it will only absorb a fixed amount of moisture. Once this limit is reached the silicon needs to be heated to arround 300degC to drive off the moisture. This is not going to happen in a solar panel. Surely the condensation does not hang arround for long once the panel is in full sun?
« Last Edit: February 26, 2005, 01:31:56 PM by jimovonz »

picmacmillan

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Re: tested ebay solar cell panels
« Reply #2 on: February 26, 2005, 02:03:27 PM »
i made a mistake on how they are hooked up...should read first two in series and the last one is in parallel...it is now 4 in the afternoon and they are still hitting close to 14 volts...i agree that dessicant won't be the cure all, but until i can sort it out, it will do i guess...ithink you're right that the sun should dry up what little moisture is in there anyhow......so, not ready to cook hotdogs from solar just yet, but i can do a little of this and a little of that....so far i am happy with them....pickster
« Last Edit: February 26, 2005, 02:03:27 PM by picmacmillan »

thumbnail101

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Re: tested ebay solar cell panels
« Reply #3 on: February 26, 2005, 02:13:46 PM »
hey pic, did u hook them to the batt. bank, yet,

if u hook all your cells up what do u think u should get for

amps?


up at five this morning reading....lol


mark:4:10 pm

« Last Edit: February 26, 2005, 02:13:46 PM by thumbnail101 »

Volvo farmer

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Re: tested ebay solar cell panels
« Reply #4 on: February 26, 2005, 03:11:38 PM »
I was thinking of dessicant the other day. I wonder if we could make a long tube with little pinholes in it. Fill it with dessicant and plug both ends. Make a hole in the bottom side of the panel, in the sealing stuff, over in the corner. Now slide the tube in the hole and put a little dab of silicone over it. If you see condensation, pull your tube out, oven bake the water out, slide it back in there and seal it again. I'd much rather do a maintainace procedure like this once in a while than have to reseal the whole panel. I also saw firsthand what water can do to a double pane window if it stays in there through too many heat-cool cycles. For some reason, it actually etches a white film on the glass. Not good for light transferrance so keep the water out of those panels.


I keep wondering what those panels are going to put out on a 90F day. It looks pretty cold in that picture and if you lose 15% of 14.5V because of heat, you're not going to have enough voltage to charge 12V batteries. Guess the only way to find out is wait till summer.

« Last Edit: February 26, 2005, 03:11:38 PM by Volvo farmer »
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RatOmeter

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Re: tested ebay solar cell panels
« Reply #5 on: February 26, 2005, 05:49:22 PM »
LOL-lipop.  r u a speaker of the English language?


Sorry, I do not wish to pick on you personally, but do you realise that while substituting the letter 'u' for the word 'you' may work well for you in a chatroom full of teenagers, in a world of people who actually know things and do things...


I don't know.  Seems like a bit of an insult to me.


I feel strongly about advancing the usage of renewable energy. An important part of that is providing practical and believable examples of the application renewable energy, as our hosts here have shown. We all have an interest and ideas on the subject, otherwise we'd not be here. We are all also limited by our various levels of command of the English language, some more limited than others.  We all also make allowances for any limitations in ability to communicate, as long as that communication is sincere and relevent.


I consider using 'u' instead of 'you' as an obvious sign of laziness, not a lack of knowledge of the language. That is why I feel insulted. I believe this forum is worthy of at least better than a minimum effort at communication.


I'm off the soapbox now. Thanks for putting up with my rant.

« Last Edit: February 26, 2005, 05:49:22 PM by RatOmeter »

picmacmillan

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Re: tested ebay solar cell panels
« Reply #6 on: February 26, 2005, 07:20:24 PM »
hi mark...hey not too sure yet what i will get with all of them hooked up...i guess i could figure it out,but i am too tired to think about it straight away.....hope you got some answers on why you can't have a tower over there...i know there is a lot more places than you that has the same problem...i guess you could think of it it this way...it's mind over matter...you don't mind cuz they don't matter... :)have a good one...pickster
« Last Edit: February 26, 2005, 07:20:24 PM by picmacmillan »

Tom in NH

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Re: tested ebay solar cell panels
« Reply #7 on: February 26, 2005, 10:56:48 PM »
Hi Pic,

I am having trouble understanding how you have them wired together. Paralleling the first two and connecting the third in series to the first two is what I think you said you did, but there would be a matching problem with that configuration, wouldn't there?


You could put them all in parallel or all in series, or if you have a fourth panel, you could tie pairs togther in parallel and then series the two pairs.


I think the way you have yours, the output is constrained. Your readings reflect the voltage and current of just one panel.


I can tell you this about my setup that uses the same cells in a 36 cell-per-panel configuration. I have 14 of these wired together in parallel. They are connected to batteries so the current is limited by the charge controller. When the batteries are low and accepting full current, I've measured upwards of 35 amps in full direct sunlight.


So looking at your three panels, if they were paralleled together, I would expect something over 7.5 amps short circuit current. Not too shabby if you ask me.

--Tom

« Last Edit: February 26, 2005, 10:56:48 PM by Tom in NH »

tecker

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Re: tested ebay solar cell panels
« Reply #8 on: February 27, 2005, 04:39:20 AM »


  At the hobby shop they sell some brass tubing I used 1/8 inch very thin wall . Put the tubing through the sealant all four corners and heat the panel up to 250 or higher with a halide work light then pump it full of argon or nitrogen . (argon is inert) .Seal up three corners while the temp is up and let the pressure settle with argon supply on . Seal at room temp.

« Last Edit: February 27, 2005, 04:39:20 AM by tecker »

thumbnail101

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Re: tested ebay solar cell panels
« Reply #9 on: February 27, 2005, 06:56:20 AM »
RatOmeter,


Thank you for your advice on my minimal "effort at communication".  I am sorry for offending you or anyone else.  


However, I too am insulted.  I am not bothered by any spelling or grammar errors in responses by you and others, but by your rush to judgment of my character and my intelligence.  


I may not strive for perfection in typing, but when undertaking projects and learning about subjects that interest me, my efforts are far above satisfactory.


I visit this website several times daily because I am deeply interested in renewable energy and want to learn all that I can about it; I already know that my typing skills are severely lacking.


Thank you again for your advice and for "putting up with my rant".  I look forward to reading more about renewable energy on this website in the future.


Thumbnail101

« Last Edit: February 27, 2005, 06:56:20 AM by thumbnail101 »

picmacmillan

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Re: tested ebay solar cell panels
« Reply #10 on: February 27, 2005, 06:58:12 AM »
good ideas tom and tecker...i suffer from electrical wisdom embarrasement, as i am dummer than a stump when it comes to electrical...when i was in college we had a teacher that didn't teach and he was our electrical teacher....i wish now that he  would have taught us so maybe i would have a little electrical know how... will try what you suggested and see what kind of amps i get...also may just take on the argon idea..i have to go check them as i left them outside all night to see what kind of shape they will be in at 0 degrees outside...pickster
« Last Edit: February 27, 2005, 06:58:12 AM by picmacmillan »

picmacmillan

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Re: tested ebay solar cell panels
« Reply #11 on: February 27, 2005, 12:30:55 PM »
hi mark...thought i would ad my little "rant", as it seems my post has led elsewhere...i enjoy your comments and you can spell it how you like when speaking to me..i am reasonable enough to understand what"u" were saying and i am not at all offended by your spelling.. ...i don't know...i am sorry that ratometer jumped you in my post...and i hope that doesn't dampen your spirits and that you will continue to respond when you feel you have something to offer....i believe both you and ratometer are good folks...i believe we are entitled to our opinions on all matters and that includes my post...just wanted to let you know where i stand on the issue as your comment was directed towards me in the first place....i am here for the sole purpose of having some fun, while learning something valuable....and hopefully in the end of it all, i will have made a couple new friends i might not have ever had the opportunity to meet, had it not been for this discussion board...and for that i am truely grateful....pickster
« Last Edit: February 27, 2005, 12:30:55 PM by picmacmillan »

ghurd

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Re: tested ebay solar cell panels
« Reply #12 on: February 27, 2005, 01:08:08 PM »
OK. Can't stand it any more!  The whole thing is making me itch!


I keep re-reading it and think you have got some serious connection problems.


You have done about the same as connecting 2 T-105s in series (good PVs), in parallel with 1, 12v 7ah (bad PV)!  Or is it a T-105 and a 12v 7ah, paralleled with a T-105!  (remember that battery post a long time ago?)


You really need to test them, at noon, each seperatly, in good sun, for a very short time so the load V doesn't change much, no charge controller, with a 12.0~13.0V battery load.


If for no other reason than to stop this itching I have.  My wife said "You read it, you scratch it!"


G-

« Last Edit: February 27, 2005, 01:08:08 PM by ghurd »
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bkrahmer

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Re: tested ebay solar cell panels
« Reply #13 on: February 27, 2005, 02:02:59 PM »
I know very little about PV cells, but the analogy to batteries seems completely off the wall to me.  My perception, which could be completely wrong, is that you put cells in series to increase voltage, and in parallel to increase amperage.  Mixing them, to get the volts and amps you desire, in any combination, seems feasible, as long as you aren't putting more amps than the cells are rated for.


Can somebody please tell me if this is correct?

« Last Edit: February 27, 2005, 02:02:59 PM by bkrahmer »

ghurd

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Re: tested ebay solar cell panels
« Reply #14 on: February 27, 2005, 02:29:03 PM »
If you have a 12V motor.  And 3 batteries, with 6v each, but 2 larger AH than the last.  You wouldn't put the 2 large 6v batteries, in series to get to 12v, and the 3rd small AH in parallel to get more amp-hours.


Like 2 'D' siries batteries, in parallel with a single 'AAA' battery.  Or a 2 'D' battery flashlight in parallel with a 1 'AAA' battery flashlight, both to the same bulb, at the same time.


A step farther.  You would not put a pair of 12v car batteries in series for 24v to get the 24v, then parallel that with a single 1.5v watch battery to get more amps.


A step more.  496, 12v car batteries in series to get 5952 volts , paralelled with a 1.5v watch battery to get more amps.  Something is going to go backwards.

Majic Smoke.  Melted fuses.  Fire.  Atomic reactions.  Or something bad.


Same idea.


G-

« Last Edit: February 27, 2005, 02:29:03 PM by ghurd »
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BT Humble

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Re: tested ebay solar cell panels
« Reply #15 on: February 27, 2005, 02:37:42 PM »
Fight! Fight! Fight! :-D


Lighten up guys, there are plenty of things happening in the world that are actually WORTH getting upset about.  That little fracas over in Iraq, for one.


BTH

« Last Edit: February 27, 2005, 02:37:42 PM by BT Humble »

picmacmillan

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Re: tested ebay solar cell panels
« Reply #16 on: February 27, 2005, 04:11:19 PM »
i will check this in the morning at noon there ghurd...i will check them individually and try what you suggest...you got my attention when you said the magic smoke...i already seen magic smoke with my voltmeter checking my wind genny and do not want to fry my panels.  :) thanks for the input and i will get at it tomorrow and report back in with my results...thanks guys...pickster
« Last Edit: February 27, 2005, 04:11:19 PM by picmacmillan »

wooferhound

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Re: tested ebay solar cell panels
« Reply #17 on: February 27, 2005, 08:50:11 PM »
As I understand it

if you are wiring Solar panels (and batteries too) in series, the max amps you get will equal the output from the weakest panel. An example would be, you have 3 solar panels in series, each puts out 15 volts, but each put out different amps.

Panel 1 makes 5 amps

Panel 2 makes 7 amps

Panel 3 makes 9 amps

Now when wired in series you will get 45 volts at 5 amps equaling the amps from the weakest panel. So if you parallel your 2 panels and then add one more in series, you will get the same output as 2 single panels in series.


This would also apply if you are making a panel from broken cells. The current will not be higher than the smallest cell in the chain. You would want to use pieces that are about the same size because the bigger pieces won't add any more cause of the smallest cell.

« Last Edit: February 27, 2005, 08:50:11 PM by wooferhound »

Tom in NH

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Re: tested ebay solar cell panels
« Reply #18 on: February 27, 2005, 09:34:18 PM »
Hi Pic,

All teachers teach and all students learn. The problem is there often is no relationship between what is taught and what is learned. Woof's note below is a wonderful explanation of what I was trying to say about your matching problem. Ghurd may very well be right about a connection problem. Since two sets of panels are wired in series, you should be getting about 28 volts in full sun, not 14. Good luck in your testing.  --Tom
« Last Edit: February 27, 2005, 09:34:18 PM by Tom in NH »

bkrahmer

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Re: tested ebay solar cell panels
« Reply #19 on: February 27, 2005, 11:34:15 PM »
Thanks, that's the clarification I was looking for.  Me not so good at amps and volts.  Give me bits and bytes instead, i'm a whiz at them.  :)
« Last Edit: February 27, 2005, 11:34:15 PM by bkrahmer »

John

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Re: tested ebay solar cell panels
« Reply #20 on: February 28, 2005, 02:50:59 AM »
Your "rant" has my hearty approval and support. I have long disliked the use of "computer shorthand" that doesn't make sense unless you are "up on the lingo". Such buchery of the English langage may have been practical when memory and storage was in short supply, but I don't believe that it is needed now and is in fact lazyness that is at the least rather iritating.


John

« Last Edit: February 28, 2005, 02:50:59 AM by John »

ghurd

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Re: tested ebay solar cell panels
« Reply #21 on: February 28, 2005, 06:53:44 AM »
The PVs look good, even the 'bad' one.


I expect both the 2 good PVs to put out the common 3a.  The bad one maybe 2.5a.  Into a 12-13v battery.  All 3 paralleled into the battery about 8.5a (3+3+2.5).

Not to shabby, 50ah a day up there where and when you'll be using them, thats 2-11w 12v CFLs 24/7.


The Isc about the same as into the battery.  The Vopen about 19-21v.


Be carefull in series.  20v bites if you are sweating.  40v bites every dang time, resulting in language inapropriate for youngsters.


G-

« Last Edit: February 28, 2005, 06:53:44 AM by ghurd »
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picmacmillan

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Re: tested ebay solar cell panels
« Reply #22 on: February 28, 2005, 07:31:30 AM »
alright thanks for the help....i understand fully what i should be doing and i will get at it, maybe this afternoon...we have something very important to do, and then i will get at implimenting your ideas...,.thanks as always....pickster
« Last Edit: February 28, 2005, 07:31:30 AM by picmacmillan »

Volvo farmer

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Re: tested ebay solar cell panels
« Reply #23 on: February 28, 2005, 08:19:12 AM »
They're 28 cell panels (.5V ea). How is he going to get a Vopen of 19-21V I think 14-16V is more like it.
« Last Edit: February 28, 2005, 08:19:12 AM by Volvo farmer »
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RatOmeter

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Re: tested ebay solar cell panels
« Reply #24 on: February 28, 2005, 08:34:13 AM »
I'm regret that I went overboard with such an off-topic rant in your thread and for that, I apologize.


It's just been a peeve of mine for quite some time that folks drop 2 letters from a 3 letter word and consider it efficient or, worse, cute. It actually decreases the readability of the text and the credibility of the author. It also ranks right up there with 'l33t speak' for appearing juvenile.


I've never met thumbnail101, but I'll say his/her well-written and articulate reply to my sorry rant has bumped them way up the scale in my estimation of their intellect. Ah, the power of words...

« Last Edit: February 28, 2005, 08:34:13 AM by RatOmeter »

sandovalch

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Re: tested ebay solar cell panels
« Reply #25 on: February 28, 2005, 09:25:42 AM »
Just wanted to add my comment,

I think Volvofarmer and I agree in the output of the e-bay solar cells, they produce about 70-80% of what the specs say. This all depends on the wiring (cable gauge), heat and which kind of glass you are using + other minor considerations.

In my case I have 14 panels in parallel (each with 36 cells) and I am producing 30-32A peak. This depends very much on the state of charge of the batteries.

My open circuit voltage for every panel is aprox. 19V and I get up to 3 to 3.2 A in short circuit.

I have tried many configurations with my panels, 3 sets of 2 in series, but as I have 36 cells in each panel, I have my best energy output with all of the panels wired in parallel. It all depends on where you are and how carefull you have been assembling your panels.

Maybe further on I will be able to get more energy out of each panel, I still have about 15# of cells waiting to go into action. I'm just rethinking my strategy to optimize output, I want to see where I'm loosing power.

« Last Edit: February 28, 2005, 09:25:42 AM by sandovalch »

ghurd

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Re: tested ebay solar cell panels
« Reply #26 on: February 28, 2005, 01:57:55 PM »
Yes, about 15v open.  I thought they were 36 cells.

G-
« Last Edit: February 28, 2005, 01:57:55 PM by ghurd »
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picmacmillan

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Re: tested ebay solar cell panels
« Reply #27 on: February 28, 2005, 03:08:04 PM »
thanks ratometer for the reply...i have always respected your opinion on here and continue to do so...i am glad we can as adults speak our mind and continue...we are having a big snowfall here tonight so i can't test my panels ,but thanks for all the help here and i see where i went wrong...hopefully i can test them in a day or so ...once the snow stops....now, off to snowplowing for me  :) pickster
« Last Edit: February 28, 2005, 03:08:04 PM by picmacmillan »

richhagen

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Re: tested ebay solar cell panels
« Reply #28 on: February 28, 2005, 04:31:54 PM »
I've built a couple of panels from them.  I've had the problems with condensation too.  It will damage the cells and connections if the water can conduct current between two parts of the panel with different voltages, such as adjacent cells, or the front and back of a cell.  The greater the voltage difference the greater the destruction, adjacent strings for example.  The electrolytic destruction will slowly destroy the conductors in the panel and on the cells.  


It seems to me that the EBay cells I've had (from CUSDN)were likely seconds that didn't quite meet the specs for the production panels.  Most functioned fine, just at lower voltage, lower amperage, or both.  When making a string of cells, it is best to match the current output of the cells as closely as possible and series connect as many as needed to make the needed charging voltage.  I used 36 as this, while lower at 16 volts or so than a new commercial panel, was sufficient for charging purposes.  The voltage drop when connected to the battery did not seem to effect the current from the panel much, so producing a higher voltage than needed to reach the charging voltage at a reasonable light level seems like it would be a waste of cells to me.  Rich Hagen

« Last Edit: February 28, 2005, 04:31:54 PM by richhagen »
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Volvo farmer

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Re: tested ebay solar cell panels
« Reply #29 on: February 28, 2005, 07:53:28 PM »
Well, that doesn't really make sense. The panels should produce the same power in series than in parallel right? If you need to charge 12V batteries, you wire them in parallel. If you need to charge 24V bateries, you wire them in series-parallel. The energy in watts produced should be the same no matter how you wire them.


Since the Voc of commercial panels is usually 20-21V, I wonder if a 38 cell panel would be more optimum with these cells. I just got the top sheet of glass installed on mine today, Best $35 a guy can spend IMO. The glass guy told me he thinks it will hold 10 years if I keep the water out of where the wires come in. These guys have been working with glass for 20 years and they say this black Butyl stuff they heat up and squirt is better than silicone. Anyway, I'm pretty committed now to 36 cell panels since I want everything to match up. If we get a clear sunny day tomorrow, I'll check my Voc and Isc again and report back. 19V seemed low to me last time and I attributed it to the high cloudy haze.


Damn, 15# in reserve? I thought I was a glutton with my 12# total. Time to find a few hundred more bucks and get some more I guess.


 

« Last Edit: February 28, 2005, 07:53:28 PM by Volvo farmer »
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nothing to lose

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Re: tested ebay solar cell panels
« Reply #30 on: March 07, 2005, 10:01:57 PM »
"All teachers teach and all students learn. The problem is there often is no relationship between what is taught and what is learned. "


That is not at all true, unless you mean the teacher is "teaching" that he don't care a bit about rather a student learns anything or not! Or the fact that he doesn't know what he is teaching himself!! I have seen several of those teaching teachers!


I went to a tech collage years ago with the worst instructor I ever saw! Body shop.

He did not TEACH, he said this is how to do something and showed us (sometimes). Then just walked by and shook his head watching students that did not get it. Then he went to a side corner of the classroom and tried to braze a crack in a cast iron engine block all day long. Or using schools gas to cut steel yard oraments!! That is not teaching!


 For example, welding with an oxy/actelene torch. I knew how just fine myself, been doing it for years. Guy behind me was shooting sparks down my back for days, teacher just walked by looking at the guy popping the weld puddle and shook his head like "He'll never get it". Never even tried to teach him how to weld, just went off and brazed the cast iron block some more. Finnally after about a week of hot sparks down my back I popped of at the guy (thinking him to be doing it on purpose) and he said he didn't know why it was happening. I showed him how to hold the torch properly at an angle and he never did it again, turned out to be one of the best in the class till he dropped out.


The teacher was NOT teaching, he was not doing his job at all in this or about 200 other things!!

 And as far as the cast iron engine block he was brazing, he didn't know the first thing about that either!! The crack was about 2" when he started and about 6" when he finnally gave up, and he seemed ticked off at me when I told him he needed to drill a hole at each end of the crack to stop the crack from spreading before heating the block anyway. I don't make a habbit of brazing cast iron, but even I know that and also it needs to be pre-heated to prevent cracks/breaking caused by uneven heating.


 In a class that started with about 18 students I think 3 maybe 5 actually graduated, a few dropped out because of the instructer not teaching anything. Others just did not learn anything because the instructor did not teach anything. Most of the ones that did learn anything at all only learned because of 2 other older students and myself taught them what they learned. The 3 of us were experienced with most of everything anyway, and what one of us was short on another knew well. One guy was a pretty good body man out of work on welfare with a baby on the way, he took the class because welfare gave him a choice of get a job, go to school, or lose the checks, and he needed the medical for the baby too. I took the class to hone my skills in working sheet metal for custom work (which was never covered at all, instructor was a buy new parts type person, forget repairs), and the third guy  wanted free use of the shop to rebuild a car and do a few paint jobs, also to buy alot of Snap-on tools at half price, the discount that was givin to students of the class by Snap-on. What he saved on the tools he bought paid the cost of the class and more!!! He bought nearly a full shop worth!

 The 3 of us were the teachers in that class for those that learned anything.


The instructer was so poor he even could not understand that mixing "one part paint to one part reducer to half part hardner" was NOT the same as mixing 1 quart paint to 1 quart reducer to 1 quart hardner" when I asked him wich was correct for mixing the paints! The instructions said both and he could not understand the 2 were not the same, of course only one can be correct. He just kept saying they were both correct and a quart is a part, but he could not see that one said mix one quart hardener and the other said mix 1/2 quart hardener!!! DOOR KNOB!! Ya Millhouse, reffering to you!

I had to contact the paint supplier and ask them what was correct, they right away saw the error and said it should be 1 quart paint, 1 quart reducer, 1 pint hardner for the correct mix.


He did not know why I cleaned 2 steel nuts very well and put them in my paint gun cup when doing a custom heavy metalic paint job. Duh, the metal flakes are heavy and settle to the bottom while painting, shaking the gun with the nuts in the paint stirs the metal back into the paint for an even metalic paint job. Otherwise you start with a nice heavy metalic and end with plain paint by the time your done.


 That was a teacher that did not teach! He was ready to retire anytime he wanted to and just did his own thing while drawing his paycheck, all the time reffering to how great he was at everything and how well he was respected among local shops and such.


No some teachers do not teach, Gateway tech collage bodyshop, Millhouse the instructor, Racine, WI. is perfect example!!! That was sometime in the early or mid 90's hopefully he retired the next year for future students sakes!!!


Real nice guy, the worst teacher though!! That includes the estimating class also! He was wrong several times about writting estimates using the book times, he was adding things that should not be added for various work and such.


That's my rant. And advise if you plan to take a body shop class, if he is still teaching after all these years, find a different class or school and avoid his!!

« Last Edit: March 07, 2005, 10:01:57 PM by nothing to lose »

nothing to lose

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Re: tested ebay solar cell panels
« Reply #31 on: March 07, 2005, 10:28:18 PM »
"These guys have been working with glass for 20 years and they say this black Butyl stuff they heat up and squirt is better than silicone."


That black Butyl is some good stuff all right. I never saw anyone heat it though myself. You can buy it in either a caulking type tube or as a tape type ribbon. Used alot for auto windshields so should be real easy to find it. Not sure if that's still whats used in all the newer cars for the windshields now adays or not. Just about all the older normal stuff used it to hold the windshields in place.

 I think the last time I bought a tube it cost me about $10 but that was long ago too.

Normall sized caulking tube for normal caulking guns same as any other stuff.


Ever tried to take out an auto windshield? If you use this stuff make sure you get your glass and stuff right the first time, pretty hard to get the glass back out when using the black butyl :)

« Last Edit: March 07, 2005, 10:28:18 PM by nothing to lose »

hapybrian

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Re: tested ebay solar cell panels
« Reply #32 on: March 21, 2005, 11:21:40 PM »
Hello!


My first post here.  I've been doing a lot of reading, and

am in the process of building my first panel using cells from

Plastecs.  Reading about those ebay cells made me drool enough

that I ordered a couple of pounds.  We'll see how that goes.


For those who are old hands in electronics, the rest of this

post is not for you!


I'm wondering how familiar everyone is with Ohm's law.  I see

concern about power and parallel vs series connections and

parallel/series connections.  Without going into too complicated

of detail, suffice it to say that for modules or panels, you

just want to make sure things are MATCHED.


If you put a bunch of cells or panels in series ONLY, all is

fine--voltage just adds up and each cell can have a different

voltage.  Just make sure they are all rated at the same current

output.  I picture it like a pipe: if you connect three pipes

together in series and send high pressure water through them,

the flow(current) is limited by the thinnest pipe, and the

thickest pipe is just wasted.  Making all pipes the same

thickness gives optimal flow.


If you put a bunch of cells in parallel ONLY, all is fine,

current adds up, and the current rating of each cell can be

different.  Just make sure they are all the same voltage!

Voltage is pressure, and if the voltage of one panel is

higher than another in parallel with it, it will be pushing

against that panel! (just like your battery at night pushes

against the panel when its voltage is higher than the panel's,

requiring the blocking diode).


It follows then, that if you go series/parallel, you'll want

BOTH the same current & the same voltage.  So, don't hook

three 12V 1A panels together in parallel (equiv to a 12V 3A

panel) and then tie those in series with a 12V 1A panel.  You'll

get 24V & 1 amp.


A final example:  Here's a 12V 4Amp system:

  3 6V 1Amp modules wired in parallel.  They are then wired

  in series with a 6V 3Amp module.  There's 12V, 3Amp.  Then,

  I have two 6V 1Amp modules.  I'll wires those in series.

  That's 12V, 1Amp.  Finally, wire the last two in parallel

  with the first four, giving 12V, 4Amps & 48 watts.

(I wouldn't recommend this though, because of impedence issues--

best to have all the same cells everywhere.)


more technical series/parallel info:

http://www.allaboutcircuits.com/vol_1/chpt_7/1.html

(or do a google).


Have fun!

Brian

« Last Edit: March 21, 2005, 11:21:40 PM by hapybrian »