Author Topic: solar energr (Read 2590 times)

brianschanafelt · « **on:** January 23, 2008, 02:21:29 AM »

the other day i started to work on a project. I took a coleman electric lantern and took it apart to get the board out. from there i put it into a little box with a switch. I had a little problem the first time i hooked it up. I crossed the wires and blew out the c2500 transistor. that really sucked so off to the electronic store to purchase another. put another in today and presto it started to work again. so i put longer wires on it so i could run it off of a 12v battery from my room witch is about six feet from the ground. hooked it up to a 12v jet ski battery that i had laying around. and then from there to my pv panel witch is 22v. had to put a blocking diode between the battery and pv panel so it does not discharge the battery. I am currently running the CF bulbs off of it right now. i started off with 12.93v about two and a half hours ago. Now it is about 12.05v not too bad huh. Hopely tomorrow it will be not so clouty the panel today was putting about 18v out with no load while cloudy and raining. I am monitoring the level of the battery with a multimeter until i get the dump load from ghurd. What do you think i should charge/discharge the jet ski battery to in voltage. I was figuring to let it charge to about 14.6v and not discharge it more than 11.9v does this sound okay. Not bad for such a small battery a little over two and a half hours and almost to 12.0v cant wait to see how long it lasts on of a full charge. hopefully it is really sunny. works great for a reading light!

"Something free is money well spent"

s4w2099 · « **Reply #1 on:** January 22, 2008, 07:25:29 PM »

I would keep the voltage at about 14.1-14.2 if you are going to be cycling it often. If it will sit for a long time then I would go down to 13.8V.

brianschanafelt · « **Reply #2 on:** January 22, 2008, 07:57:34 PM »

I am going to be using it every night i hope so it will be sitting no longer than twenty four hours. will it hurt to leave my multimeter on for more than a couple of hours? Guess i will find out sooner or later it is only a ten dollar cheepie. sometimes cheepies are the best ones!

TomW · « **Reply #3 on:** January 22, 2008, 08:40:36 PM »

Brian;

I have a digital multimeter that has literally been "on" for years. Main issue was battery getting used up. I fixed that with a wall wart as a battery replacement plugged into the inverter.

If it is one of those cheaper analog meters [with a needle] there is no battery involved in reading voltage. Leaving one of those on a circuit should be no problem. The drain on the battery from the meter reading volts is miniscule and should not drain the storage battery significantly.

Hope that helps.

Cheers.

TomW

brianschanafelt · « **Reply #4 on:** January 22, 2008, 08:50:44 PM »

Thank you tom this is a digital meter. About how long does the battery in these last if left on all the time?

TomW · « **Reply #5 on:** January 22, 2008, 09:11:20 PM »

Brian;

My Radio Shack with a 9v battery would go a week or so on a fresh battery, if I recall right.

I think, as the battery goes flat accuracy suffers, too. No big deal for our purposes.

If you rigged an external battery pack setup from "C" cells or something it would go lots longer on one "battery". A, AA and AAA batteries don't give much run time compared to bigger cells. Size does matter with batteries.

Hope that helps.

Cheers.

TomW

brianschanafelt · « **Reply #6 on:** January 22, 2008, 10:36:15 PM »

is there a way to hook it up directly to my battery with a resistor?

ghurd · « **Reply #7 on:** January 22, 2008, 10:38:57 PM »

NO!

They blow up.

G-

wooferhound · « **Reply #8 on:** January 22, 2008, 10:54:19 PM »

A resistor will slow down the charge rate

it will NOT prevent overcharging . . .

The battery will eventually charge up to the same voltage as if No resistor were there at all

brianschanafelt · « **Reply #9 on:** January 23, 2008, 12:24:02 AM »

No i mean hook up my multimeter to my battery!

claude · « **Reply #10 on:** January 23, 2008, 01:31:54 AM »

Hi,

A while ago I used this:

http://www.thebackshed.com/Windmill/articles/PanelMeter.asp

It works great if you're fortunate to find old network cards. The isolated power supply used in those will output 9V for your multimeter. You only need a 5V regulator (LM7805) to feed the power supply straight from your battery.

There's no way you can measure your own battery using its voltage for that. (unless you use a analog style one) For digital, you need a isolated power supply.

Claude

Nothing40 · « **Reply #11 on:** January 23, 2008, 03:11:36 AM »

Those little Valor DC-DC converters are great! I've 'robbed' several from old network cards. They can only supply about 200-250ma max. though,but thats plenty for a meter.

blueyonder · « **Reply #12 on:** January 23, 2008, 08:19:53 AM »

a while ago i was a bit bored . so thought i will test battery and charging circuit on the car. faithful multi meter in hand i started with battery .14.5 volts.

sumthing was not right so started engine and got 18.00 volts.

i was nearly crying .i had a big problem here.

so cutting a long story short it turned out the battery in the meter was low.

a low battery was giving high readings. how odd.

that meter is long gone now .smoke got out when i tried testing volts with it set at amps.

ive never had that problem in the past. but it did show a low battery warning on the lcd screen i never saw it .it was only a small symbol .

so beware with readings . in sunshine and bright light its hard to see on the gray sreen. maybe the expensive ones are better .

good work brian. your at the bottom of a ladder and getting your foot on the first rung. but getting up the ladder is great fun . its hard learning . but i am learning from your posts and the answers you get . carefull with that prop .cheers john

brianschanafelt · « **Reply #13 on:** January 23, 2008, 01:00:13 PM »

You would be suprised how much your brain will take in! It seems that when i wake up. I eat information for breakfast and dinner. Sometimes I cant go to bed until one or two in the morning. And when i finally go to sleep i am dreaming of what i am going to do next. it seems that my brain goes into overload and in the morning everything seems to make a lot more sence. My grandma always laughs at me because she has never seen a twenty three year old so interested in renewable energy. But i say that is good because everybody needs to start somewhere. Even if it is at the bottom of the ladder!!!.

"something free is money well spent"

brianschanafelt · « **Reply #14 on:** January 23, 2008, 11:11:17 PM »

Today i totally got rid of that old jet ski battery and broke out the two new jet ski batteries i had in the box for summer. no Electrolite in them yet so i filled them and put them on a good charge. Also i pulled the deep cycle out of my boat only been used twice in October so it had a good charge but i still toped it off. went and got a little inverter "modified sine wave" it is only a 150w for .01 of a second, 70w for ten minutes and 60w continuous. put all three batteries together for twelve volts and re wired the inverter so i could put Alagator clips on the wires. then i have a 13w cf bulb from Edison i hooked it all up and i have been running it for three hours not too bad i guess. but i have a question on the voltage i did a little test and i have found out that i have been using .26 of a volt for the first hour and for the last two i have only used .27 of a volt why is this? started off with 12.56v one hour later it was 12.30v and two hours after that 12.03. then i shut if off so i didn't discharge the batteries too much. but i still don't know why it used as much for a hour as it did for two hours. any help much appreciated. thank you all

brianschanafelt · « **Reply #15 on:** January 23, 2008, 11:32:16 PM »

Sorry i messed up it is a 25w 0.32a 1830 lumens by

AbyssUnderground · « **Reply #16 on:** January 24, 2008, 08:47:12 AM »

Battery voltage is not linear with discharge. It all depends on the load and state of the battery itself, not its charge state. To get accurate state of charge readings you need to take specific gravity readings.

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