10 a ammeter wiring.

[Sunking]

SK to the rescue. From your drawing it appears you used an Analog Meter, and if that is true you connected it backwards. Digital meters swing both ways. Positive and Negative.

There is a STICKY that tells you how to do this. Unfortunately The link to the Drawing is broken and I have it for you below.Make damn sure you read it and fully understand OK?

If you want something permanent, use a Shunt and volt meter.



MODS PLEASE COPY THIS LINK BELOW AND FIX THE STICKY with the right link. Or unlock the thread and I will do it.

[james quinn]

Thanks Sunking

[azdave]

Ever heard of Google? There are hundreds of how-to's for this (and dozens of videos if you don't like to read).

https://www.google.com/search?q=measure+solar+panel+output+with+multimeter&oq=measure+solar+panel+&aqs=chrome.2.0j69i57j0l4.8551j0j8&sourceid=chrome&ie=UTF-8#q=measure+solar+panel+output+with+a+meter&tbm=vid

[SunEagle]

Ever heard of Google? There are hundreds of how-to's for this (and dozens of videos if you don't like to read).

https://www.google.com/search?q=meas...+meter&tbm=vid

Be careful about suggesting watching a YouTube video. Most of those will not provide a true and accurate explanation of what is going on in the video or are really a safe operation.

If I truly believed in everything I saw on YouTube I would have invested in a couple of perpetual motion machines a long time ago.

[azdave]

Be careful about suggesting watching a YouTube video. Most of those will not provide a true and accurate explanation of what is going on...

This is the first I'm hearing that information on the internet is sometimes incomplete or inaccurate. Good call!

[J.P.M.]

This is the first I'm hearing that information on the internet is sometimes incomplete or inaccurate. Good call!

Utube == The new idiots' bible.

[rhouser]

I too am a new member here and also new to Solar. Like James, I wanted to confirm amps out (of a 12v Lead Acid solar controller designed to recharge single car batteries in no start scenarios ). Like James, I forgot to account for the battery. I cut in my DMM between the Positive out on the controller and the positive terminal of a 30 amp AGM 12 V battery. Like James, my DMM circuit locked out immedicately (but no fuse burning). It took me 3 trys to figure out I was running a 10 AMP DAM circuit against the SOLAR CHARGER + the 30 Amps in the battery at 13.1 volts. I am really surprised my Harbor Freight digital multimeter didn't fry.

Second bite of the apple: I then disconnected the Solar Charger from the battery and went across positive to negative no load (open voltage) and got a reading. I am not sure this is a reading I want either. I like the idea of the shunt meter and have been looking at a couple. Would it be just as well to go with a straight shunt installed as above and then "meter it" as I need to? My main solar controller is still in the box. It has metering and I picked up an MT-50 that runs off the RS-485 jack as well for when I am ready for "phase 2". Right now, I am still working on figuring out how things work.

I am 67 years old and have been doing DC stuff since the 1960's, but, mainly car wiring, boats, dc motors, generators and that kind of stuff. The new tech digital world is amazing and the PV technology is beyond belief.

Thanks for this great forum. I will try not to be overtly stupid (no promises).

v/r RCH

[max2k]

I too am a new member here and also new to Solar. Like James, I wanted to confirm amps out (of a 12v Lead Acid solar controller designed to recharge single car batteries in no start scenarios ). Like James, I forgot to account for the battery. I cut in my DMM between the Positive out on the controller and the positive terminal of a 30 amp AGM 12 V battery. Like James, my DMM circuit locked out immedicately (but no fuse burning). It took me 3 trys to figure out I was running a 10 AMP DAM circuit against the SOLAR CHARGER + the 30 Amps in the battery at 13.1 volts. I am really surprised my Harbor Freight digital multimeter didn't fry.

Second bite of the apple: I then disconnected the Solar Charger from the battery and went across positive to negative no load (open voltage) and got a reading. I am not sure this is a reading I want either. I like the idea of the shunt meter and have been looking at a couple. Would it be just as well to go with a straight shunt installed as above and then "meter it" as I need to? My main solar controller is still in the box. It has metering and I picked up an MT-50 that runs off the RS-485 jack as well for when I am ready for "phase 2". Right now, I am still working on figuring out how things work.

I am 67 years old and have been doing DC stuff since the 1960's, but, mainly car wiring, boats, dc motors, generators and that kind of stuff. The new tech digital world is amazing and the PV technology is beyond belief.

Thanks for this great forum. I will try not to be overtly stupid (no promises).

v/r RCH

Welcome!

I am a little confused what you're trying to measure. If you could clarify that it would be easier to help. Otherwise all your DC experience still applies, electrons flow the same way they did from the beginning, we just got more convenient tools and more ways to control those flows.
If you just follow couple simple rules your DIMM might last longer: connect voltmeter in parallel with a circuit and amperemeter- in series.

Batteries or any other voltage source don't have amperes 'in them' waiting to attack- they just have max output current they can supply. If you try to connect too small resistor which would cause too high current according to good old Ohm's law I = V / R they either reduce their output voltage or burn some fuse inside. Voltmeter has very high resistance so if you connect it to them it won't create any noticeable current. Amperemeter on the contrary has practically 0 resistance so if you connect it to a voltage source it will cause very high current and then something will give up, in many cases- your amperemeter (your DIMM in amperemeter mode). Since DIMM switches from being voltmeter to amperemeter by turning its mode selector it often leads to burned DIMM. Better ones have separate input in amperemeter mode to make you explicitly move input from one DIMM contact to another in hope to get your attention .

[bcroe]

I like the idea of the shunt meter and have been looking at a couple. Would it be just as well to go with a straight shunt installed as above and then "meter it" as I need to? My main solar controller is still in the box. It has metering and I picked up an MT-50 that runs off the RS-485 jack as well for when I am ready for "phase 2". Right now, I am still working on figuring out how things work.

I am 67 years old and have been doing DC stuff since the 1960's, but, mainly car wiring, boats, dc motors, generators and that kind of stuff. The new tech digital world is amazing and the PV technology is beyond belief.
Thanks for this great forum. I will try not to be overtly stupid (no promises).
v/r RCH

As you have discovered, that simple ammeter on the blackboard is not so simple in real circuits.
Errors easily blow things up, you need to shut down operation to insert it, DC loves to draw a
big arc. The installed shunt recommeneded by several above solves those problems.

Stupid questions aren't a problem. Its those who refuse to understand or are insulted by the
answers. Bruce Roe

[Sunking]

OK guys there are two ways to measure current.

1. Hall Sensor Effect which I will not discuss but has to do with magnetic fields. Many Many meters use it as it does not require any physical electrical contact. It is th emeters with a Clamp you put around the wire. Not a lot of accuracy.

2. Convert current into voltage using a SHUNT. A Shunt is nothing more than a small precision Resistor you must insert in-line with the circuit. This is what your DVM uses, and you have to put your meter In-Line. The Shunt resistance is very small, so small in fact you can consider it a short circuit. That is why your meter blows up if your meter is configured to measure current and you connect the meter across the battery.

OK to use a Shunt, like I said you install the Shunt In-Line of one of the circuit conductors. Ohms Law states Current x Resistance = Voltage. A Shunt is a FIXED Resistor, and the Voltage will vary depending on the amount of current flowing through it.

Shunts are rated either 20 or 50 millivolts full scale. So if you bought a 50 mv 100 AMP SHUNT means at 0 Amps produces 0 volts, and at 100 amps produces 50 mv. Also tells you a few other things. It tells you the Shunt Resistance has to be 50 mv / 100 amps = .0005 Ohms and with 100 amps flowing burns 5 watts of power. All Ohms Law.

Your meter circuit then has to convert voltage to current, or you can use pencil and paper to calculate current. Millennials will need a calculator or cell phone app. Example above lest say you measure 30 mv on a 100 amp shunt. What is the Current? You use Ohm's Law or simple ratio.

Using Ohm's Law of Amps = Voltage / Resistance we know the Shunt resistance is .0005 Ohm's . .03 volts / .0005 Ohms = 60 Amps.

Using ratios Amps = Measured Millivolts / Millivolts Full Scale x Full Scale Current. We know full scale voltage = 50 and full scale current = 100 amps, so we have 30 / 50 x 100 = 60 amps.

[rhouser]

Max2k: I am wanting to watch the throughput from the PV array to the Solar Charge controller. Again, I am in phase one of learning. I want to see what is really happening. I then want to watch to delivery of power out of the solar controller to the BMS (battery management system?). I have purchased a MPPT solar controller. I want to watch and compare voltage output from the controller to the BMS and compare it to the current input to the controller from the PV array. I know that the MPPT algorithm works and is real, I just want to see it.

Bcroe: +1 on the big arc and also the danger of high voltage DC. Anything that can weld its own breaker is basically scary. This is why I am doing my experimenting and learning in a 12 Volt 6 amp environment. Mistakes are less harmful/expensive. I am going to have to do some more reading. I do not want to necessarily have to push all my line voltage through the/a shunt. I think I recall that I can build a "tap" that bleeds off enough of the main line to monitor Watts - VolltsxAmps. (I know... I should already know I guess.

Sunking: I think the Hall Effect is why the big voltage AC ring meters can read the line voltage without breaking into the cables.

When in doubt, throw more money at it. I don't have a solar store that I know of in the area, but, I do have a "HAM Radio" shop. I just came back with a Powerwerx Precision Watt Meter and Power Analyzer that is rated for 60V and 50 amp continous with130A peak. I still want to look into a "Tap". I hate it when I remember something but can't remember why it is important.

v/r RCH

[Sunking]

Max2k: I am wanting to watch the throughput from the PV array to the Solar Charge controller. Again, I am in phase one of learning. I want to see what is really happening. I then want to watch to delivery of power out of the solar controller to the BMS (battery management system?). I have purchased a MPPT solar controller. I want to watch and compare voltage output from the controller to the BMS and compare it to the current input to the controller from the PV array. I know that the MPPT algorithm works and is real, I just want to see it.

Bcroe: +1 on the big arc and also the danger of high voltage DC. Anything that can weld its own breaker is basically scary. This is why I am doing my experimenting and learning in a 12 Volt 6 amp environment. Mistakes are less harmful/expensive. I am going to have to do some more reading. I do not want to necessarily have to push all my line voltage through the/a shunt. I think I recall that I can build a "tap" that bleeds off enough of the main line to monitor Watts - VolltsxAmps. (I know... I should already know I guess.

Sunking: I think the Hall Effect is why the big voltage AC ring meters can read the line voltage without breaking into the cables.

When in doubt, throw more money at it. I don't have a solar store that I know of in the area, but, I do have a "HAM Radio" shop. I just came back with a Powerwerx Precision Watt Meter and Power Analyzer that is rated for 60V and 50 amp continous with130A peak. I still want to look into a "Tap". I hate it when I remember something but can't remember why it is important.

v/r RCH

I understand what you want to do. But watching current does not tell you anything without the voltage and time element factored in. I cen easily send 1 amp of current into a MPPT controller and come out with 10 amps. But that does not tell you anything. If you did not know better could be lead to believe you had a gain which is false and impossible because in practice is a loss. If I go in at say 100 volts x 1 amp is 100 watts. On the output I have 10 amps at 9 volts or 90 watts. That is a loss not a gain. Now that is just power, not energy. To find energy requires TIME.

You can do what you want no problem at all, but current alone does not tell you anything. It is as meaningless as battery Amp Hours.

AC electric meters do not use Hall Effect Sensors, they use Current Transformers and Potential Transformers. Both Current and Potential (voltage) Transformers use ratios. Example a common CT is 50:1 where 50 amps input = 1 amp output. That 1 amp is then passed through a Shunt and generates a voltage for the Transducer to read. Voltage is also stepped down to work with a 5 volt transducer. So they read both voltage and current which gives them power. Throw time element in and they have Watt Hours to bill you with. However FWIW you can use Hall Effect to measure both AC and DC currents. Issue is Hall Effect is not real accurate.

Thing is DC does not work with transformers. So with DC you have to use either Shunts or Hall Effect to convert Current to a Voltage. Shunts are more accurate and dependable.

Take away here is to use either a DVM or Shunt requires you to put the device in-line, not across the load like voltage. Essentially you cut either the positive or negative polarity lead. Then insert your shunt or meter in to make the connection you cut.

A picture is worth a thousand words. Note both drawing are the exact same thing electrically. One shows a Shunt, and the other shows a DMM. Your DMM has a Shunt Inside typically a 10 amp 100 mv shunt. Point is it goes in line. Pay attention to polarity colors on the meter wire. No big deal on a DMM as it will just negative current. Example - 5.00. If analog you let the smoke out.

[rhouser]

Sunking, thank you for your last explanation. I can actually follow most of it. I had to look up some of what you were saying to stay with it, but, I feel I understand what you are teaching me. I appreciate the time you took to give me a detailed answer.

I plugged in the Watt meter between the PV array and watched it as the voltage moved into the Solar Management Controller (SMC). You were right. It served no real purpose. I did verify that I was getting the same Voltage and Amperage readings at the PV-IN panel on the SMC and I got some extra practice with wiring in Anderson Powerpole 45A connectors.

A key thing to note at this point is that I have a complete working Solar based collection going from Panel through Solar controller to Battery Array. I have placed the MT-50 and Temp Sensor into the array and set the SMC Battery Management to GEL (no specific AGM setting is available). This is all set up on a bakers rack in the shade as a proof of concept model. The only parts I have omitted are that I did not connect anything to the LOAD OUT terminals on the SMC and I did not connect an inverter to the battery bank. Maybe later.

As a question from a totally NEW solar old guy, why would you want to drop current from the Load terminals pre-battery bank. What would you want to connect directly out of the SMC that could/should not come out of the battery bank? Count this as my first dumb question of the day.

v/r
RCH