How to measure amps

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quique
quique Solar Expert Posts: 259 ✭✭
in Solar Beginners Corner #1
Here is my ammeter and I want to measure the amps produced by my 100w solar panel:

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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #2
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    Re: How to measure amps
    quique wrote: »
    Here is my ammeter and I want to measure the amps produced by my 100w solar panel:

    1. Read the manual for the meter. Look for how to measure 10A DC.
    2. Make sure the meter leads are not connected to anything.
    3. Read the manual for the meter. Look for how to measure 10A DC.
    4. Probably plug the red lead into the top jack instead of the middle jack and set the switch to 10A on the DCA side.
    5. Read the manual for the meter. Look for how to measure 10A DC.
    6. Cover the panel so no light falls on it.
    7. Disconnect the panel from everything else, especially any batteries.
    8. Connect the red meter lead to the panel + and the black meter lead to the panel -. Make sure it is a solid connection on each.
    9. Read the manual for the meter. Look for how to measure 10A DC.
    10. Uncover the panel, read the meter, cover the panel again.
    11. If the meter did not read anything, Read the manual for the meter. Look for how to measure 10A DC.
    12. With the panel still covered, unfasten the leads and immediately put the red lead back in the middle hole!
    SMA SB 3000, old BP panels.
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  • quique
    quique Solar Expert Posts: 259 ✭✭
    #3
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    Re: How to measure amps

    I'm sorry I did not make myself clear. I did read the manual and I do understand how to set it to 10 DCA and the black jack. My doubt was more as to how to set up the leads. I thought but for some reason there was a different kind of set up but your exclamation made it perfectly clear that it is basically the same positive to the positive And negative to the negative. Thank you very much!
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #4
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    Re: How to measure amps
    quique wrote: »
    ...and the black jack.
    ??
    You are very welcome. I did want to cover both the meter side and the lead side of the process, just in case.
    SMA SB 3000, old BP panels.
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  • quique
    quique Solar Expert Posts: 259 ✭✭
    #5
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    Re: How to measure amps

    Ok I had $70 lying around so I bought this:

    Attachment not found.

    As inetdog pointed out, I read the manual, but it may as well be written in arabic. It says:

    Attachment not found.

    1) To measure AC Current (large <400A) set meter to A~ and clamp wire.

    2) Select DC or AC. It shows a picture of a button I dont have in my meter, even though these are the instructions to my meter:

    Could I measure the amps coming in from a pair of 2 solar panels, in parallel, each with an Isc of 8.54A? The Imp is actually 8.10A. So in parallel it would be max 16.20A.

    but my question is, the wires come down from the roof into my CC and out to the BB. Could I clamp the meter around the + coming into my CC and measure amps?

    thx
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  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #6
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    Re: How to measure amps

    It's only rated to <2000uA. According to your user guide, 8+A will fry it.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #7
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    Re: How to measure amps
    quique wrote: »
    Ok I had $70 lying around so I bought this:

    Unfortunately, although it is probably labelled as an AC/DC meter, the clamp part can only measure AC amps. And the DC range using the leads is probably too low to be able to measure the current from your panels.
    For $70 you should be able to get a meter that can actually measure DC using the clamp (try Sears), which will be much more useful for PV work.
    SMA SB 3000, old BP panels.
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  • rich
    rich Solar Expert Posts: 62 ✭✭✭✭
    #8
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    Re: How to measure amps
    quique wrote: »
    Here is my ammeter and I want to measure the amps produced by my 100w solar panel:

    Attachment not found.

    I got that exact meter from the dollar store...2.99`$ it fried the first time I measured amps, the guy is correct, the instructions are complete crap at the very least...not to mention funny....u need to get a better meter my friend.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #9
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    Re: How to measure amps

    This is the "good enough" $60 Sears DC/AC Current Clamp + DMM -- digital multimeter (the thermocouple probe died almost immediately--but the meter itself has been working great for the last few years).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #10
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    Re: How to measure amps
    rich wrote: »
    I got that exact meter from the dollar store...2.99`$ it fried the first time I measured amps, the guy is correct, the instructions are complete crap at the very least...not to mention funny....u need to get a better meter my friend.

    It's rare for them to fry for no reason, they can't tell you to disconnect a battery and only measure the solar panel, it's just too specific...

    I had the sears clamp meter and it gave up one day and I went back to an old ampro stand alone, dial in zero, clamp meter. I couldn't find my goodish multimeter and have been using one of the half doz, "throw away meters" I purchased as give away meters at Harbor freight the last time they were $2. It seems to be in the ball park.

    I'm NOT saying the Sears meter isn't a good piece of equipment, It might have been the cheap 2032 batteries I replaced the originals with, It didn't last long after that.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #11
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    Re: How to measure amps

    I have the Sears meter. I find that regardless of what setting the dial is at (except off), the numbers on the display constantly jump around all over the place - even when not measuring anything.
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  • quique
    quique Solar Expert Posts: 259 ✭✭
    #12
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    Re: How to measure amps

    My mistake for posting 2 different meter pictures in the same post.

    I don't mean the original yellow meter. I'm referring now to the orange-black Klein tools CL-1000 meter.

    According to the instructions, depending on where you set it, you can read <2000microamps or less than 400Amps. So I should be able to read 16amps using the <400Amps, shouldn't I?
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #13
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    Re: How to measure amps

    I'd say someone that doesn't have a clue has mislabeled that meter as a AC / DC clamp meter and it isn't.

    Klein Tools CL1000 AC Clamp Meter


    http://www.kleintools.com/catalog/clamp-meters/400a-ac-clamp-meter
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #14
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    Re: How to measure amps

    I agree that the Sears meter is not a high end meter--But it uses a pair of AAA batteries, not 2032 button cells. My meter does not jump around unless the signal is jumping (just used it to find a short in a laptop DC power cord).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    #15
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    Re: How to measure amps

    I bought the sears clamp meter. I have only used it to clamp check dc amps. Knock on wood, I love it, and thank bill for posting the link in an earlier post. So far so good and so much neater then just trying to check shorted amps.

    Thanks
    gww
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  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #16
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    Re: How to measure amps
    BB. wrote: »
    I agree that the Sears meter is not a high end meter--But it uses a pair of AAA batteries, not 2032 button cells. My meter does not jump around unless the signal is jumping (just used it to find a short in a laptop DC power cord).

    -Bill

    I wonder if mine is defective. It shows a reading (fluctuating) at all settings, regardless of whether the leads are connected to anything. Maybe I'll try changing the batteries.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #17
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    Re: How to measure amps
    BB. wrote: »
    I agree that the Sears meter is not a high end meter--But it uses a pair of AAA batteries, not 2032 button cells.
    I stand corrected, at least by the manual, I can't find the meter, perhaps it was my multimeter that needed the 2032s after the Sears meter died...it's not the Ampro it takes a 9v, out of curiousity I checked.
    BB. wrote: »
    My meter does not jump around unless the signal is jumping (just used it to find a short in a laptop DC power cord).
    They do have to be zeroed regularly, something about how it measures through the clamp, electro-magnetic fields?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #18
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    Re: How to measure amps

    Yes, with DC current clamp meters, they use a transistor to measure the magnetic field... And it will drift over minutes.

    The "ZERO" Button works unlike any other meter I have used...

    With ZERO off, the meter displays whatever the uncorrected DC reading from the sensor is...

    When you push ZERO and the "zero" turns on in the LCD, it takes a snapshot of the sensor reading and subtracts that from the LCD reading--So ZERO only zeros when the button is pressed to on and there is a "zero" on the LCD display. And it will zero with the meter disconnected, or if there is current flowing, it can "zero" out that steady state current too.

    Pressing ZERO again turns off the zero mode and displays uncorrected sensor data again.

    It took me a few minutes of playing with my car's electrical system to figure out how ZERO worked--Prior to that point, I through I had a bad meter.

    Depending on how accurate you want the readings--You may have to zero every couple of minutes due to drift (if you want 0.25 amp or better accuracy on 40 amp scale--as I recall).

    -Bill

    PS--Should add that the meter will display a "-" (minus sign) if the DC current is flowing "backwards" through the clamp. And display a blank sign for positive current flow.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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