15 amp meter Help

newguy1975 · May 2016

Hi guys am new to this site am looking for some help with my solar set up.
I been wanting to add an amp meter to my set up I have a 15 amp analog amp meter that I cant get to work right, I was told you DON'T need a shunt for 15 amps or lower am not to sure..
The set is one from the solar panels to the meter then one to the Batteries .
What happens then is I get the amps reading but then my battery's go from 12v to 16v when i disconnect the amp battery wire the volts drop to normal am i needing a shunt? is the wiring wrong or a solar blocking diode

I have 2 100 watt solar panels in parallel
1000 watt inverter
Renogy Tracer 40 Amp MPPT Charge Controller
3 12v batteries

mike74820 · May 2016

if your meter is like mine, you need to just put it on the plus side wire from the controller to battery to measure the amps going to the battery.

BB. · May 2016

First--Yes, for low current circuits, you can get meters that take the full current and display the value (all of the current flows through the meter body).

For higher current circuits, a "shunt type meter" is used to make the wiring (and meter) simpler. Shunt type meters measure the voltage drop across the shunt (typically 0.001 to 0.250 or 0.500 volt drop across the shunt).

Note: It is the meter "type/model" that decides if you need a shunt or not. It is possible to use an external shunt on a 15 amp meter--But I would not suggest gonig down that road (accurcy issues, possible wiring/safety issues).

I am not quite sure I understand your first question. It sounds like you are measuring 12/16 volts on your battery terminal? That is (sort of) normal... ~12.x volts under load and ~14.x volts when charging.

Are you seeing different "numbers" when you have the amp meter connected or not?

-Bill

newguy1975 · May 2016

The volts only go to 16 + V when the meter is connected the second i remove the amp meter the volts drop back down to 12-13 Volts
almost like its bypassing the CC and going straight to the batteries...

newguy1975 · May 2016

any way i could see how you have yours wired..

BB. · May 2016

Assuming your normal connection is Solar panels -> solar charge controller -> battery bank

Then you should see ~12.7 to 14.5 volts on your battery bank when the batteries are charging and the sun is up high in the sky (and should see ~14.4 to 14.8 volts on the battery bank for ~2-4 hours to ensure the battery bank is fully charged).

When you install the current meter to measure solar array current... You take one wire from the solar array (typically the negative lead, for safety reasons) cut it in 1/2. Put one lead on one terminal on your amp meter. And a the other lead on the other amp meter terminal. If the meter reads negative current (or meter needle goes below zero amps), flip the two leads on the terminal (reverse the current flow in the meter body to fix polarity).

The only way I can see what is going wrong is if you connect the + side of the solar panel/charge controller to one amp meter terminal, and the Battery + side of the output of the solar charge controller. In that case, the Amp Meter will be "shorting" the solar charge controller and causing all of the available current to flow from the solar panels directly to the battery bank. You may see > 15-16+ volts on the battery bank in this case (will not hurt the battery for a minute or two--But if left connected this way for minutes-hours-days will kill the batteries).

-Bill

newguy1975 · May 2016

Am not understanding this cut it in 1/2. Put one lead on one terminal on your amp meter. And a the other lead on the other amp meter terminal

mike74820 · May 2016

bill is saying cut the wire in half, then you place the amp meter in between the cut wires. as you can see in my picture it the * wire is cut in half goes from the controller to battery to measure amps

newguy1975 · May 2016

I see that , and the second wire to the solar panels + -?

mike74820 · May 2016

Image: https://us.v-cdn.net/6024911/uploads/editor/7w/w24wjeriomsd.jpg

there is no second wire, the meter is in the middle of the wire that goes from controller battery + and to the battery postive post on the battery it self

newguy1975 · May 2016

can it be that easy... and this will tell me how many amps my solar panels are giving out

mike74820 · May 2016

it is that easy if your meter dont have a shunt, i use mine to see how much my controller is putting out to the battery, but the same principle can be used for checking the panel amps. on my picture you can see the wire above the meter, i can cut that wire in 2 and put and amp meter in between the cut wire and check the amps coming from the panels

mike74820 · May 2016

http://www.ebay.com/itm/Analog-Panel-Current-Meter-Ammeter-Amp-DC-DC30A-Class-2-5-Plastic-UsFreeShip-/271339089664?hash=item3f2d11ef00:g:Cr8AAMXQUmFSn2oe this is the one i bought off ebay it doesn't need a shunt

newguy1975 · May 2016

Am Gona try that mine is an analog 15 amp meter with no shunt I been trying for about 2 weeks to make this amp work . Knowing how many amps my panels are producing. . Thanks for the info.

newguy1975 · May 2016

15 amp meter

oil pan 4 · May 2016

I bought the same kind of meter mike has for my small solar rigs. One wire in, one wire out, yes it is that simple.

BB. · May 2016

For doing diagnosis work on solar power systems (and other DC systems like cars, trucks, boats, etc.)--Look at getting a DC current clamp type meter. This one from Sears is ~$60 and is "good enough" for our needs.

With current clamp meters, you simply clip the clamp around 1 wire and read the current. No cutting/stripping of wires needs (much safer).

Beware--DC Current Clamp Meters are a bit tricky to learn. Because of the their internal sensor(s), you have to zero them every minute or so--Otherwise they do drift from Zero (and while I like the Sears meter, the "ZERO" button works "different" than most other meters I have used. Read the instructions and experiment, or ask here for details).

-Bill

mike95490 · June 2016

I love the smell of burnt wires in the ampmeter.
You really need to understand the electrics of how different meters work, leaving a meter set on amps, and measuring volts the next day, will get you a rude ball of plasma in the face.
Just saying that sticking a meter in and not knowing why it works, is likely fry something.

newguy1975 · June 2016

I agree knowing is best , but I just can't seem to give up on this or find some one too hook this up that knows , I do so much want a permanent amp meter on my wall to always see the amps thary panels are making...
My panels are 100 watt each 2 total with 5.6 amps each wired in parallel I live in Daly City ca fog city I would be lucky to see 7 amps total on a good day am using a 8 awg wire to the CC this should be good I would think.

oil pan 4 · June 2016

oh that's normal. You never get what they are rated for. At 63% of what they are rated for you are doing pretty good. The meter is reading the panel side, right?

newguy1975 · June 2016

I have not had a chance to see it work it's been two days of fog the meter reads 0, it moves a bit so am still not sure if it's connected right.

BB. · June 2016

You should see ~10-20% (typically) in foggy weather--I would guess.

If you see zero, then something is wrong (or the battery bank is fully/100% charged and the charge controller has turned off charging current).

Debugging. Take a volt meter and measure the voltage at the Charge Controller Solar Input terminals and the Battery Output Terminals.

If you see ~12.5 on the battery, and 12.5 on the panel input--Then there is (probably) no charging going on and no current flow.

You can also measure the voltage drop across the amp meter terminals--If you see 0.5 volt or less drop, all is probably OK with the meter connections. If you see >>0.5 volts, then you may have a bad meter/bad connections.

-Bill

newguy1975 · June 2016

Today was the first sunny day all week so I hooked up the amp meter one to the CC and the other to the solar panels .. the needle will move up to 2.5 amps for about 5 seconds then it drop back down to 0 it will move abit but never above 1.5 amps broken amp? Full sunny day , 2 100 panela I should be seeing more the 2 amps..

westbranch · June 2016

Hmmmmm... have re-torqued all your connections?
Copper has a tendency to 'flow' after tightened and the connection becomes loose and needs to be re-tightened about 24 hrs later...

BB. · June 2016

What is the voltage of the battery back at this time? Sounds like the charge controller is cycling, and thinks the battery is fully charged?

Yes, you should get around 5 amps from each panel in full sun.

You can try "jumping" (electrical connection) from + panel to + battery (bypass the charge controller).

You may have poor electrical connection somewhere, or even bad solar panels (it can happen).

-Bill

oil pan 4 · June 2016

Or a bad charge controller.

newguy1975 · June 2016

Cc is working fine. I went up on the roof and checked the panels on a foggy day they were still making 3.5 amps each . I ordered the 30 amp meter giving on my 15 amp meter.

newguy1975 · June 2016

How can I test my panels to tell me how many watts they are giving out I would.like to test each panel

BB. · June 2016

Can you measure the voltage at the charge controller input and output terminals for me? 3.5 amps on a less than clear day is not bad.

-Bill

newguy1975 · June 2016

I went on on the roof tested the panels volts and amps, 2.6 amps on one and 2.8 on the other one.. volts 21.2 and 20.9 ,I don't how to test watts

westbranch · June 2016

multiply Volts times Amps = watts (roughly that is) so just under 60Watts per panel

15 amp meter Help

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