Solar Panels..Again!

Submitted: Sunday, Apr 05, 2009 at 10:01
ThreadID: 67545 Views:2389 Replies:4 FollowUps:6
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Gday All,
Ive now have an 80w and a 40w solar panel and decided to set them up on a battery each and test them, and have a few issuses.


The 80w puts out 13.81 volts and the 40w 15.23volts.
I assume that is to do with the size of the regulator?

So I thought I should check the watts........
Volts x Amps = Watts?????
Grab my multi meter to check the amps and I cant remember how to, ....... threw the manual about 10 years ago!

Both batteries are of the same age out of the same appliance
( electric doors on the hospital) and were both drained before I started.
After 2 hours of testing, the battery being charged by the 40 watt panel had 8.21 volts in it and the one on the 80 w panel only had 6.22 volts???????
Im assuming the 80watt panel has put in more amps ????????
Or is something wrong? ( me again maybe?)
Ive attached a picture of my multimeter...if any one could tell me how to use the bloody thing for testing amps it would be appreciated!!!!

Cheers
Hairy

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Reply By: Member - bungarra (WA) - Sunday, Apr 05, 2009 at 10:35

Sunday, Apr 05, 2009 at 10:35
Hairy

Amps is a measurement of current. The only way you can get any multi meter to measure amps is to put it in line between the power source and the appliance using the power

In other words between the solar regulator and the battery or the battery and the appliance (fridge etc)

Leave the earth wire as untouched and break into the positive wire and using the probes on the multi meter allow the current to flow in one of the probes into the multi meter and then out back through the other probe and then connect that to the other end of the positive circuit that you broke into to complete the circuit

Make sure the multi meter is on amps and be ware that some of the cheaper multi metrs may only measure up to 10 amps

As for your batteries I reckon they are stuffed
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Follow Up By: Maîneÿ [wa] - Sunday, Apr 05, 2009 at 10:52

Sunday, Apr 05, 2009 at 10:52
yes, as above, but instead of using the 'term' *break into the positive wire* I will suggest, simply attach one of the Multi meter leads to the end of the ( + ) lead that goes to the battery and use the other Multi meter lead to attach to the battery, forming the circuit through the Multi meter and giving you the reading in Amps.

Yes of course it's the exact same thing as written above, but those reading this with absolutely zero electrical knowledge (as many claim) won't be looking and wondering how or where to "break in" ??

Mainey . . .
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Follow Up By: Hairy (NT) - Sunday, Apr 05, 2009 at 10:53

Sunday, Apr 05, 2009 at 10:53
Gday Bungarra,
Have I got the multimeter set up right in the bottom photo?
What makes you think the batteries are nakered?

Cheers


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Follow Up By: Hairy (NT) - Sunday, Apr 05, 2009 at 11:00

Sunday, Apr 05, 2009 at 11:00
Gday Mainey,
My electrical knowledge is very liminted I know, but what are trying to say. Hahahahahahahaha

LOL
Cheers
Hairy
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Reply By: Member - John and Val W (ACT) - Sunday, Apr 05, 2009 at 10:59

Sunday, Apr 05, 2009 at 10:59
Hairy,

Sounds like you have a few issues.

First - how to measure amps. Warning -This is a very quick way to damage your meter if you get it wrong. Amps are a measure of the FLOW of current, so you want those amps to flow through the meter. If it is set up to measure amps though and you accidentally connect the meter leads to the battery terminals, the huge current flow WILL kill the amps capability and probably the whole meter. For this reason, after you've measured current, always change the meter back to volts, exactly as in your photo.

How to do it - set the switch to the 20 A= position (pointing due west) and move the red lead to the "A" terminal on the left hand side. To measure the current flowing from the solar panel to the battery you should connect the red meter lead to the positive (red) lead from the panel, and the black meter lead to the POSITIVE side of the battery. The negative (black) panel lead goes direct to the negative side of the battery. After you've made your measurement, move that red meter lead back to the V terminal (as shown in your photo) so as to avoid accidentally damaging the meter. (And switch the meter back to volts to avoid confusion.)

I would expect you to see a bit over 2 amps from the 40W panel and about 4.5 amps from the 80 watt one.

Your voltages at the batteries are a worry. Are they 12 volt batteries??? If they are, you should be seeing over 12 volts at the terminals, and with the panels connected, over 13 volts. (Unless they are very very dead.)

Final warning - after every current measurement, always move the red lead back to it's voltage terminal!!!!!

Hope that helps,

Cheers

John

Watts = volts x amps as you say. BUT - the panel's highest wattage (which is where the spec is taken) is at about 17 to 18 volts, not the 13-14 volts you'll see when charging.



J and V
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Follow Up By: Hairy (NT) - Sunday, Apr 05, 2009 at 11:08

Sunday, Apr 05, 2009 at 11:08
Gday John,
Yeah mate, the batteries were very dead....that reading was with the panels diconected, after being hooked up to the panels for two hours.
Thanks again for the Info!
Ill give it ago.

Cheers Hairy
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Follow Up By: Member - bungarra (WA) - Sunday, Apr 05, 2009 at 11:11

Sunday, Apr 05, 2009 at 11:11
Looks like John & Val have given you excellent info...my screen is not giving a good picture of your meter and was difficult to read

Their detailed answer is perfect and makes no assumptions as to the laymans electrical knowledge..

a quality answer by them... well done
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Follow Up By: Hairy (NT) - Sunday, Apr 05, 2009 at 11:34

Sunday, Apr 05, 2009 at 11:34
I just tried that and got no reading at all?
Im guessing I probably blew my meter up mucking around with it earlier?
I might ring GregF and blow up his multimeter? Hahahaha

Why did the 40w panel put in more volts than the 80w???? Just the regulator size?

Thanks agaiin
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Reply By: Member - bungarra (WA) - Sunday, Apr 05, 2009 at 11:06

Sunday, Apr 05, 2009 at 11:06
The picture is bluury but looks like you have the dial on DC volts you need amps...roughly 180 deg from where it is now....the Dc is the dotted line the AC is a ~

I think your batteries might be stuffed because after a couple of hours of charging they should be at at least 12+ volts and should also be showing similar reading during charging

let them rest for half an hour and they should be at least 12+ volts
after that

what Mainey said is same as me I just assumed that bit was logical where "to break in"
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Reply By: GregF - Monday, Apr 06, 2009 at 17:05

Monday, Apr 06, 2009 at 17:05
The Blurriness is not the Camera, but is actually the way Hairy sees things normally after 18 Burbons
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