460 Seven Sensors tested: Measuring Current with Microcontrollers (Arduino, ESP32, ESP8266)
ฝัง
- เผยแพร่เมื่อ 22 ก.ค. 2023
- During my summer break, I reupload successful videos of the past (for your rainy Sundays). This one aired on April 5th, 2020.
Measuring current is simple. Right? You just take a multimeter, connect it to the two cables, and read the value.
If you want to do the same with a Microcontroller like an Arduino or an ESP, things get a little more complicated. Let’s dig into it to see how it works! And which is the best sensor for our projects?
Video about AC sensors: • #347 Measuring Mains V...
Sensors in the video:
MAX4080: s.click.aliexpress.com/e/_Dku...
INA169: s.click.aliexpress.com/e/_dVM...
INA219: s.click.aliexpress.com/e/_Dn0...
INA3221 (order black module): s.click.aliexpress.com/e/_DlW...
ACS712: s.click.aliexpress.com/e/_dS7...
ACS758: s.click.aliexpress.com/e/_d66...
WCS1800: s.click.aliexpress.com/e/_Ddf...
The links above usually are affiliate links that support the channel (no additional cost for you).
Supporting Material and Blog Page: www.sensorsiot.org
Discord Channel: / discord
Github: www.github.com/sensorsiot
My Patreon Page: / andreasspiess
If you want to support the channel, please use the links below to start your shopping. No additional charges for you, but I get a commission (of your purchases in the next 24 hours) to buy new stuff for the channel
My Amazon.com shop: www.amazon.com/shop/andreassp...
For Banggood bit.ly/2jAQEf4
For AliExpress: bit.ly/2B0yTLL
For Amazon.de: amzn.to/2r0ZCYI
For Amazon UK: amzn.to/2mxBaJf
For ebay.com: ebay.to/2DuYXBp
profile.php?...
/ spiessa
www.instructables.com/member/...
As an Amazon Associate, I earn from qualifying purchases - วิทยาศาสตร์และเทคโนโลยี
Corrections and additions:
. Ohms law was used wrongly (th-cam.com/video/Cg-4GjLeeAI/w-d-xo.html )
- This video is about DC sensors (albeit some of them measure current in both directions).
- The video about AC sensors is here: th-cam.com/video/Vb9-pbLdsfQ/w-d-xo.html
- The INA219 can measure currents in both directions
Just came to check if you corrected that the Ina219 can measure in both directions, and was pleased to see it 👍🏻
I have what I call a "Micro Solar Setup" that runs 4 of these modules for 2 solar panels charging 2 x 12v on each panel/solar charge controller, which I then series'd up to give me 24v. I did it this way so that I could have "Roughly" 24v on a rather long, but flimsy power cable, that supplies all the routers, fibre and switches which have buck converters down to their applicable voltages.
Works like an absolute charm, although currently I may have to add another set of panels, as, I am drawing as much as I put back daily 😔
I suppose this is what happens when you get carried away with IOT, and just keep adding more stuff to the already burdened system 😂😂😂
I love those INA219's by the way, they are super useful, easy to use and their accuracy just blows my tiny little mind most of the time 👍🏻
I second this. I have micro solar mppt charger for my garden measurements. Using INA3221 I had no issues with current flows in both directions (charge/discharge cycles)
18:04 "mA per mA" -> "mV per mA" :)
At 3:05 the current is wrong. It should be 10A instead of 100A. Narration is correct, shown equation is incorrect. Calculated result is correct if 10A is considered. (th-cam.com/video/Cg-4GjLeeAI/w-d-xo.html)
Thank you Andreas. You often save me from wading through the datasheets of inappropriate devices and board modules, and wasting my time looking for what I need. A 22 minute video brings me up to speed on the commonly available sensors, and their pros and cons. This is one such occasion.
Glad you liked the content. And thank you for your kind words!
The INA219 sketch you used does have the voltages back to front. Your rant at 13:35 - the 219 allows the difference between bus and load to be both positive and negative, so it can measure current in both directions - very useful. I think your comment at 15:26 is therefore not accurate. It’s one of my favourites.
You are right. My mistake!
Perfect timing and great overview and explanation! Exactly what I need for my smart home water level sensor 👍
Maybe you also watch my videos about water level sensors? BTW: I like your channel a lot!
Watch out for a catch with the hall sensors - magnetised screws! I chased around for ages trying to find and null drift , only to find that every time I tightened the screws my magnetised screwdriver was changing the field around the screw and effecting the hall sensor
You could try plastic screws.
Thanks for the tip. A mistake that takes some effort to discover. But I am sure you learned something ;-)
@@edinfific2576 or Brass , which was what I expected in a terminal block
I'm using a handfull of them on my boat to monitor the currents of the alternators, battery charger, solar panels, and house buss. My solution to the stray magnetic field issue was to incorporate a calibration screen that allows me to change the error offset values for each on the fly. I measure the current with a DMM, then jump to the calibrate screen, select the appropriate source, and simply change the value until it matches the measured value. I'm in the middle of developing my battery management system for my boat so I haven't done much testing on long term stability nor accuracy of them over the range. The accuracy issue isn't a big deal. I've got 20A, 50A, and 100A sensors to improve precision/resolution on the smaller ranges where it's more important. In the end, it's not a big deal as I'm using a microcontroller so I can easily expand my simple error offset value to a table with as many offsets as I need. In my case high precision isn't really needed. If I find there's a stability issue over relatively short periods then I'll design a method of auto-calibration.
FWIW, I had a similar issue with measuring voltages with the Arduino Mega that I'm using for this project. They too were very unstable, I found I was constantly chasing them around over the space of an hour or two. Finally tracked it down to the fact the Mega was running off the boat batteries, as the battery voltage dropped it caused the 5v supply change. Since the ADC of the Mega defaults to the 5v supply as a reference, it constantly changed as a result causing the instability. I solved the issue by incorporating a precision voltage regulator and fed the Mega VRef pin with it.
Beautiful. I had in the past looked at all these types of sensors, and it’s always very difficult to determine which ones are appropriate. Thanks for sharing
Glad you liked the content!
French new embedded engineer here. I just discover your channel Andreas. I must have listien to this video 6 times by replaying back some portion of it. Great content. Subcribed!
I am so enjoying the content of this video that I needed to say it back again! Thank you!
Welcome aboard the channel!
Thanks again Andreas! Bought the INA3221 for my solar project. Was originally going to design myself. But you saved me so much time. You're the best!
Thank you. Glad the video was helpful.
Detailed instructions and specifications don't get any better than what Andreas presents!
Thank you! I am honored.
Good catch on the variants of the INA3221 breakout board available from circuit designers with strange ideas. I agree with other comments though that some of the TI shunt sensors can handle reverse current sensing. From the datasheet: "VIN+ and VIN- can have a differential voltage of -26 V to +26 V; however, the voltage at these pins must not exceed the range of -0.3 V to +26 V". The datasheet shows an example of reading a -80mV shunt voltage from the CH1 shunt-voltage register.
You are right. The INA3221 can measure both directions. My mistake!
The ACS712 is a wonderful chip and it helped me in a big project. I was measuring mains at 230 Vrms in up to 20 Amps (tested). The inner resistance of the ACS was so small (
Thank you for sharing your experience! This video is focused on measuring DC, and I left a link to a video about AC sensors. There, as you describe, some other problems have to be solved...
I have similar good experience with these little Hall devices for my (kW range) power boards.
They are remarkably reliable, pretty accurate, bi-directional, fast and fully isolated.
Those properties solve a lot of issue in the design of power converters.
I most often use the TMCS1107 devices (op to +/- 22 A) which are very similar to the ACS712 series, but a bit more accurate.
As always, interesting subject, explained precisely, maximum informations popularized with tact and generosity while remaining short and precise. Thank you Mr.
Glad you enjoyed it!
Your a wizard, Andreas. I've been playing with the idea of using a current sensor with LIFEPOv4 batteries to power and possibly then shutdown a Pi and been looking at creating a circuit to create an effective UPS with a couple of cells. So your video is very timely. I had already purchased a couple of the INA219 boards as this was what was used on a Pi UPS board that I managed to fry! So was particularly at using this chip. Thanks for your info and cross-sections of boards out there. I think may have chosen the right option! Thanks, as ever for your useful info.
I am sure the INA219 is a good choice. Other than I said, it can also measure negative currents. So you could even measure battery charging ...
Danke viel mal Andreas
This video came at precisely the right moment as I am trying to implement overcurrent sensing on a 2 cell lithium ion powered project.
Good luck with your project!
6:00 you dont need negative opamp for this, you can use a divider and bias input of the opamp with a positive voltage, then the negative voltage would add to that and the resulting voltag could always be poisitive
Also a good possibility if you pay attention to the ground of the MCU.
I work for a long time on a project (so far: ESP32 I2S MCLK and current sensing), figure out some things, and only afterward do I come across your excellent videos on the exact same topic. One of these days I will look for a video from you first!
FWIW, I appreciate the reviews of the ICs specifically. I make PCBs so don't need breakout boards, though they can be useful to test and dissect.
I ended up with a hall sensor for isolation (TMCS1101-A4, 5V version for max sensitivity, my load is ~100-200mA, 24VAC). Also had to figure out an RC filter (R1K, 300nF) and a better ADC than the ESP32. Hall sensors have a lot of HF noise, the RC filter is required to make any use of it.
I don't think being inline means a hall sensor has a burden voltage. It's just how the IC routes the trace under test very close to the hall sensor.
High amp ICs require special consideration for thermal dissipation. I found many users on the TI forums talking about their burnt ICs. It should be possible to do it right though.
Anyway, nice video! Thanks!
Searching TH-cam is always a good choice if I start a new project ;-)
Very well done. One must also keep in mind temperature stability and drift and the concept of dithering in quantization. Resistors must all be 1% and for really important accurate measurement, consider a precision, temperature compensated voltage reference. Finally be sure to characterize the wiring/connector drops on any voltage measurement.
I agree with all your additions!
Thanks for addressing all those points in the beginning, like implementation issues, high/low side monitoring, etc.
Unfortunately, I think most of the viewers missed a lot of it, or just didn't understand. (Judging by comments)
I thought you did a great job explaining it!
Maybe they just need to watch again, or even a few more times?
Good stuff. Thanks for the comparison of all these sensors. And for pointing out a couple that have "gotchas." I might not have noticed that before buying, because I would assume they made sense, like not having 3 sensors measuring the same load!
Thank you for your feedback. I like people who watch my videos not understanding all. They are ambitious and want to learn ;-)
After being educated as an electrical engineer in the eighties I ended up in IT and now more low level stuff and Robotics.
Obviously my knowledge is stale. Your back to basics with a modern twist is exactly what I need.
Cool. Similar here. Trained in the 80s and returned after the age of 55...
Another great video
Impressive and interesting test as always 😊
Thank you!
Around year 2000 I had to measure current in a project and I used a similar approach shown between 5:00 and 6:00. Back then I didn't have the option to buy a INA219 module. After the rectification and filtering of the power supply, only the op-amp was powered. Then I put a diode on the negative rail creating a voltage step (0.6 - 0.65 V) to the remaining circuit. This way I created a negative supply for the op-amp. It was not a symmetrical supply, since the positive rail is the same for the entire circuit, and the negative rail was only a diode drop from the main circuit. But it worked since the voltage drop on the shunt resistor "fitted" inside the voltage drop of the diode.
Good idea! Creative.
The INA228 and INA229 are very nice sensors measuring current in both directions also having voltage , current , power , energy and temperature registers working up to 85v.
Good to know. Thanks. Unfortunately, I did not see them on breakout boards :-(
@@AndreasSpiess The INA226 is on break out boards but only 36v but same pin out as the INA228 so can be swapped on the board if you have a hot air station. I have designed a board to take them with 200amp shunt , 48v to 5v isolated converter and I2C isolator for my 48v off grid. Stuart Pittaway has boards and code for Arduino .
I think that the INA219 and all similar modules can measure bi-directional current without any problem.
Correct. It can measure both charging and discharging of a load, i.e. current either way
You are right. My mistake!
I seem to remember one old application note describing use of a floating differential sampling and storing front end. In principle, it had a 2-pole, 2-throw relay and a capacitor that stored the sample, then delivered the stored voltage to the amplifier input, when the relay changed state. Of course the relays are not a favored thing in the era of all solid state systems. Yet, an interesting addition to the collection of different topologies.
Most of the current ADC have such a "Sample and hold" architecture built in. So the learnings of the past are used in a different implementation
Another good choice is the Texas Instruments AMC1302. It's a galvanically isolated op amp designed to sense current through a resistor with ±50 mV burden voltage. It needs two power supplies, one isolated, but that can be done with a small transformer, a square wave (Arduino TONE using a spare pin) diode and capacitor. Working isolation voltage 1500 VRMS.
They also have an AMC1311, with a 2 volt high impedance input designed to measure voltage with the same galvanic isolation. Both have ~100kHz frequency response. I've used them to make efficiency measurements on high power audio amplifiers by monitoring the voltage and currents of the mains supply and amplifier output.
Thank you for the info!
Voll cool, danke Andreas,
Ich bin seit zeiten auf der suche nach einem guten Modul, ein guter Vergleich hat mit noch gefehlt.
Dann hoffe ich, dass du das richtige findest!
Very fortunate for me, I was just researching this.
So maybe you saved some time ;-)
@@AndreasSpiess it helpedms avoid researching some things that would not have helped.
Ina226 fits my needs perfectly. I am using it with a 1khz loop.
I've always enjoyed your presentations, and occasional jokes.
A critique/recommendation. When mentioning the shunt resistor in the multimeter being "smaller", while I understand exactly what you meant, "smaller" may have been interpreted by some, as a physically reduced size, and not, reduced resistance. Perhaps, "of less resistance" or "lower resistance", would have been better.
As always, great presentations! You're someone, I wish to emulate. Inspirational!
You are right. However, "smaller" resistor is a common expression in electronics. The answer of ChatGPT: When someone mentions a "smaller resistor," they are indicating that it has a lower resistance value, which means it allows more electric current to flow through it compared to a resistor with a higher resistance value. Conversely, a "larger resistor" would have a higher resistance value, impeding the flow of electric current to a greater extent.
@@AndreasSpiess
I have learnt something important. Don't rely in advice from ChatGPT! 🙄 It's obvious, a 100k surface mount resistor, MUST be bigger, than a 10 ohm 1/4 watt through hole resistor. 😏
Regardless, your presentations are excellent! 👌
Interesting - I was just thinking that if you were measuring small currents, and you wanted to use the inductive clamp method, maybe you could wrap the wire 10x around the lead and then just divide the measured current by 10? (Or however many loops)
Also, this is awesome! I’ve tried measuring voltage and current with an Arduino in the past, and have had mixed results. This should help.
Yes, you can wrap the cable around the measuring loop and do the division. I do this often to increase sensitivity.
informative and accurate as always.
i would have liked to see a little more explanation of “high side” & “low side” measurements.. and when /why you might use each…. also a slightly better explanation of “common mode” voltage specs and where/why this is V important if using it on high side.
ive heard a lot of users on forums burning up chips because they used a “low side” spec chip for high side measurements…. not realising that its NOt the shunt voltage thats critical when spec’ing it for high side..
i use a lot of INA226 (in “24V systems”) … a lot of users “forget” that a 24V system will commonly see 29V when batteries are charging … (similarly for 12V systems … 14.5V ++)
The most important word of a (good) TH-camr is "no" to keep the videos short enough ;-)
The mistakes you mention can be avoided by my favorite word: RTFM. And: Sometimes, smoke from a defective part is good for learning (I know what I am talking about).
After going over a lot of options I ended up going with the INA237 due to availabilty, cost and simplicity. Coupled with an Attiny212 and i2c LCD made a nice USB-C volt/current meter with PC data link.
It's a nice chip and only a small programming change from the INA219 but with greater common mode and resolution. Worth having a look at.
You are right; the newer "models" of the INA family are attractive. And some seem pin-compatible. You can use the same Chinese boards and change the chip...
@@AndreasSpiess when I saw Apple was moving to 28V USB-C modes I had to move from the INA219, that basically was the only reason I did the redesign and move to the 237; the 219 certainly provided a perfectly good platform and still does.
Ohms Law is I=U/R and not I=UxR as said in your video at 1:42
You are right. My mistake!
Das sollte/darf nicht passieren!!!!
Schulnote 6!!
One advantage of sensors with analog output is that you can use them in a analog closed loop.
I agree.
Is the response time fast enough ? For instance for current limiting a high power (10W) LED at 500khz ?
@@shodanxx You have to consult the datasheet.
Right on time! I'm on a project where I want to measure voltage and current of a 90V solar panel. The INA219 only goes up to 26V, so I'm curious to see what alternatives you're reviewing. Going to watch it now!
I am also used to INA219. 26V is good for my purposes. But also curious now about alternatives.
Use a voltage divider and multiply the result. It should work very nicely.
90V is a high voltage! And a big panel;-) The solution of piotrswiatkiewicz3259 might work (you need 2 quite stable voltage dividers)
Hello@@AndreasSpiess The panel is actually not that big. It is a used GS-55 by GS-Solar. It's some sort of copper based thin-film PV in a glass panel. It originally promised 55 Wp and has a Vo of 86V, relatively high compared to traditional silicon based PV's. I intend to make a power monitor to see what it actually delivers and to see what can be improved. Your video came just at the right time! Thank you and thanks to @piotrswiatkiewicz3259 for the great suggestion.
@@MaxintRD BTW: I still remember your music library ;-)
I'd add SCT013 clamp sensor, it's easy to use and you can choose from many versions, depending on the current and precision.
looks like this is a current transformer based sensor so that will only work on AC, I think this video was specifically directed at DC (using hall effect and shunt resistors)
You're right, I didn't realize that DC was the goal. I always used it for AC and actually never thought this method cannot work on DC. Good catch, thanks.
Thanks Andreas! A great overview on current monitoring modules and very timely too! I'm looking at a project to remotely monitor and control some 12V(nominal) fused circuits for an amateur radio setup. Are you aware of any modules that can reliably/safely switch 12VDC up to 50A for the main, and as much as 25A for a branch that may have a 100W transceiver on it? I might just have to go with automotive relays and a driver circuit, or figure out a suitable high side MOSFET switch circuit, but I was hoping for a nice easy to use module! 😂
For my new remote station (Flex6600), I use DC solid-state relays (shown in one of my last mailbags, if I remember right). I do not want to have a mechanical relay on 24/7. For the current measurement, I use the BMS function.
Schöne Übersicht über Stromsensoren ..... Weiter so ... Auch mit dem Akzent 😉😉😉 Echt tolle Videos
Vielen Dank!
Yaay i was wanting an update on this :)
Maybe it is time...
Hello, nice video and very well explained as always. Just to confirm, you mention that the sensor doesn’t support reverse current, but at least for for INA219 I know that it does measure both directions. I have a setup where I use a solar charger to a Li-ion, where the sensor is in series to the battery, and I can see positive current values when it’s charging, and negative when it’s discharging the battery.
You are right. My mistake!
So that's where I messed up. I tested the shunt version but did not like the accuracy. I am not 100% sure but I probably did not connect to both GNDs. Learned something. Thank you.
Indeed, these ground problems are not easy to discover!
Nice Pointer!
Thanks!
Hi Andreas..very interesting. What IC would you use to check if a smartphone is charging or not (an IC in the middle between charger and smartphone)?
Any DC current or power meter should do.
for clarification, the INA219 can be used to measure current in both directions. I have used it before to measure positive amps (discharging battery) and negative amps ( charging battery) in a project before. Measuring the current is a matter of identifying which side the voltage is lower... thats the direction of flow.
You are right. My mistake (I pinned a comment with the correction)
Thanks!
Thank you for your support!
Working with a Raspberry Pi Pico W I had issues with the fluctuation from a voltage divider as well, but I stabilised it in the software by using the average of the last 10 measurements as the value for decision making. It worked well and produced a value that was very stable in comparison with a bench multimeter. The example is in python:
# Calculate the average of the last 10 Batv values
batv_average = sum(batv_values) / len(batv_values)
Good idea! BTW: If you want to save some RAM space, there is even an easier formula where you do not need to store all 10 values (moving average).
@@AndreasSpiess Oh I didn't know, I will look into that. I know moving averages but I didn't know that there was a specific function for it. Thank you for letting me know.
@@yannkitson116 No function, just the normal formula.
Hi, my teacher always recommend your vídeos
He is a wise person ;-)
Thank you Andrea.
There is also the INA226 which can handle voltages up to 36V against 26V for the INA 219 (usefull for my Oscar 100 final PA...)
73 de HB9IIU
Thank you for the tip!
Great stuff ... Andreas do you care to present some longer distance radars (100-200m) like used for collision avoidance in cars ?
So far I did not see them in a reasonable price range :-(
Hello. Awesome video. Please what sensor would you recommend for a large scale use, say for instance measuring all appliances in a house
This question cannot be answered in a TH-cam comment because it depends on your situation.
Thanks for the great video and explanation as usual. I'm still not clear about AC... do these sensors measure AC? Obviously if you used an analog input, you might measure varying voltage based on the AC sine wave timing. I assume the ACS7xx chips do measure AC since they can measure mains.
This video is about DC sensors. I made another video about AC sensors. Some of the DC sensors can measure currents in both directions.
Nice video for current sensor, I am from ME major. I don’t understand why I need to measure a current linked to arduino? Why can’t they separate in two loops? Say I want to measure if my water pump is turned on from line voltage I could use hulls sensor in it’s loop and don’t bother my low DC supply to Arduino.
Even for the shunt sensor at 5 A range, can’t design them in a different loops? Like you have example with resistors? Also if I use a transformer to supply say 7 and 5 volts DC then I have more choices to handle my application in a different loop and don’t bother normal working voltage for Arduino? Thanks
This was just an example load. Most people will measure the currents of other loads.
I've used a current transformer to measure AC .
That clips a ferrite core over a power cable of an external device and provides an AC voltage signal with amplitude proportional to the current... Usually DC biased so that no negative voltage is seen as the microcontroller. It's instantaneous current so the AC has to be measured rapidly to determine the average current.
With some software trickery, and assuming that the load is sinusoidal, you can play software tricks to measure the voltage at a certain angle after zero crossing. That avoids lots of number crunching. One can adapt to AC frequency at startup and any drift in phase offset over time by monitoring the zero crossing voltage at the expected time... Sort of phase-lock.
If you need true RMS then it's calculation intensive. Most of the time you don't need it for control purposes where you wish to avoid damage through over-current.
The phase-point measurement could be sufficient in many application where it can react at 4 times the AC frequency, if you choose.
The sensors shown here are mainly for DC. I made a video about AC sensors and put a link in the description. Usually, you do not only want to measure current but, as you describe, also want voltage and phase shift for AC sensors...
Hi Andreas, very good overview, also you use Hall sensors, but I'm missing XMR sensors like TMR sensors. They are much more accurate. Any Plans for TMR? Best regards Thomas
I never heard of these sensors. They seem to be interesting for high-accuracy applications. Are they already available for the Maker budget?
If you use a very small Rsense, the first three chips are very capable at higher currents. It is very common to use 0.1 or 0.01 ohm Rsense.
I agree.
The Hall effect sensors like the ACS721 also have the problem of hysteresis, in other words, the "zero current" output voltage changes
depending on what was the last current you measured. Measure +1A, then note the "zero" voltage (nominal Vcc/2). Now measure -1A. Now check the "zero" voltage, and it will have changed by several % of full scale.
Thanks for the info!
Measuring current on my solar system has been a recurring interest for me for several years. This year I have implemented a circuit based on Stuart Pittaway's excellent TH-cam channel. I'm using 3 INA229 chips (charge controller load, and battery current) on a custom PCB. The chip uses an SPI interface. Current measurement are by directional, with very low zero offset. Therefore coulomb counting for battery charge level is extremely accurate and repeatable from day to day. I show the board in a short overview TH-cam Video if interested.
Impressive project! I had a similar problem (8x300Ah battery) but went the easy way: I bought a Daly BMS and interfaced it using an ESP8266 to node-red. So far, I do not have experience with how accurate the ampere-counting is.
@AndreasSpiess Have you considered making a video about how to program an ESP32 C6 with zigbee to make your own zigbee-devices, such as plant sensors, remotes and other sensors? This would be a game changer for DIY smarthome.
As soon as Espressif supports Zigbee in the Arduino IDE...
@@AndreasSpiess Why not ESPHome? 😊🤷♂️ Easier in my experience and integrates directly to Home Assistant.
@@DIYtechie I use ESPhome whenever possible...
Thank you, Andreas. Have you ever used a Rogowski coil to measure alternating current?
No. I had to google it ;-)
Which of these sensors are appropriate to measure reactance, the phase difference between voltage and current, to differentiate apparent power versus real power in inductive loads such as motors, solenoids, coils, antenna and to perform power factor correction of digital devices power supplies ?
Soaking of power supplies, what happened to the "super power" power supply ?
This video is mainly about DC. I made a video about AC msensors.
Very interesting ! Will you make a video where you explain how to program the esp with grafana and co to give a nice current reading over time in a webbrowser ?? ;) Or is there already one ?😅
I made one or two videos about MQTT, node-red, influxDB, and Grafana. Search for IOTstack
@@AndreasSpiess I knew it ! :D Thanks :)
I would expect that when measuring mains, being AC, you would been some code and a bit of bandwidth on the mcu to calculate the RMS equivalent current value? It looked like all your tests were done with a DC source.
These are mainly DC sensors (some can measure currents in both directions). I made a separate video about AC sensors and added the link in the description
Ina226 can be used high side or low side, but it does still add a burden voltage.
I agree. But on the low side, the GND of the load is no more GND of the sensor. Not easy for many designs...
@@AndreasSpiess yes I agree. I am using top side for my designs.
@@cccmmm1234 Me too...
Could we get a video on powering microcontrolers with redundant power supplies? What type of powersupply is the most reliable? What makes power supplies fail, which component fails first from heat, cold, moisture etc. How to protect board from the elements and lightning etc.
Kinda obscure toppic, but I think it would be interesting for people making IOT stuff that is a royal pain to get to when needs replacing.
IOT devices usually are extremely low power. So the reliability of power supplies was never a particular problem for me. Most of the time, they run on batteries or on a 5V USB power brick.
Many thanks - please consider an episode on how an MPPT controller dynamically changes the impedance that is ‘seen’ by a solar panel depending on the load, where load seems to be a combo of battery charging needs , and the inverter input . I have looked on the internet for months and still can’t find a clear technical explanation . The question arose when my inverter showed 400 watts solar panel output on a sunny day with a 4.6 Kw array - the battery was fully charged and most appliances turned off.
MPPT controllers are switching buck converters. They can adjust the voltage ratio between the input and the output voltage to match the MPP of the panel(s). Input power is always similar to the output power. This is why your converter only consumed 400W from the solar panel when the battery was full.
@@AndreasSpiess thank you - I’m trying to build a small test unit or simulate on ltspice so the “ penny drops “ as reading vs understanding something are often worlds apart .
@@AndreasSpiess The "all in one inverter" appears to have inputs from the 1. utility , 2. solar panels , 3. battery - The outputs are- 4. the load , and 5. the battery charging . I was trying to correctly position the panels both azimuth and angle by measuring what came out of the panels to input(2) . This is where the confusion started as the displayed, or measured value depended on the load (5) . A collogue suggested I switch on a reflow over to ensure that load was more that the inverter could deliver and then measure but that caused inverter to shutdown - Perhaps I am asking the wrong question, and there is a better way to measure the output of the solar panels , ideally measured every 5 minutes over a day ? If I get this to work the plan is to install a slew drive to track azimuth daily and I will adjust the angle every 2 months manually between seasons .
@@hedleyfurio Think of the buck converter as a transformer for DC with an adjustable turn ratio. The turn ratio is used to shift the working point on the curve of the solar panel to match the power needs of the output.
@@AndreasSpiess Thanks again : so summary could be : The buck converter is like an inductor,( viewed from the solar panel output) , with an input impedance of 2PifL , where by varying the frequency / duty cycle (f) , the input impedance changes which thereby allows more or less current to flow from the solar panel . The MPPT controller ' seeks ' for the optimum impedance point to then matches that to allow maximum output . If you have a situation where the load requirements are LESS than the solar panel output then the input impedance is increased to match the instantaneous load requirements , meaning the excess energy in the solar panel , that is not supplied to the inverter/mttp charger will be dissipated as heat .
The INA226 has one advantage over the INA219 that you did not mention: it can also be used to measure current on the low side (placed in the ground wire) because it has a separate Vbus input to measure the supply current. By the way, both chips state "bidirectional" in the datasheet so you can place one INA226 in the wire to the battery and measure both charge and discharge currents
it can also measure voltage
You are right (I made an error about the direction). However, I do not like that the load is not connected to the same ground as the INA if used on the low side. This will fool a lor of people, I think...
@@AndreasSpiess I also prefer high side current measuring but sometimes I do not have that option. My 36V battery charger for example outputs 42V of charging voltage which is too high even for the INA226 to allow current measuring in the positive voltage wire.
Something you did not address here is frequency response. Normally all you need to measure is low frequency like 50/60 Hz, but sometimes you need to measure much higher frequencies and the resistor types are the only ones with any real higher frequency response. And the stuff I was measuring was only in the kHz range. Not really RF frequencies.
I agree. These sensors are mainly used for DC. I left a link to a video where I covered AC sensors. So far, I did not cover higher frequency measurements as this is not mainstream business...
What would be the best of these to measure an AC or DC ground fault detect or current leak to ground down to 1M?
I assume the same rules apply. The shunt has to be quite big if you want to measure very low currents. But I never tried it.
Thanks again, I am looking for affordable DC current clamps for the PV strings, to integrate it in my home automation system.
I hope you find an appropriate one.
@@AndreasSpiess up to now unfortunately not. For sporadic tests I am using the Voltcraft branded UT210, but I have nothing to integrate in the PV system and in my automation system. At least nothing which is not too expensive.
@@klassichd10Maybe you try a WCS1800?
@@AndreasSpiess Thank you for the hint. I though about that, but I had to open the inverter and to remove the string cables to feed them through the hole. I want to avoid to lose warranty,
I am still hoping, that there will be a variant to clip on.
@@AndreasSpiess We might come closer: "Hall split core" seem to be the keywords. 30A DC ca, 40 EUR. Expensive for nice to have. I will still wait a bit. The inverter also transmits values, but I have 2 strings in parallel at one of two MPPT trackers.
Wouldn't it be possible to just use a hall effect sensor and measure the magnetic field induced by the current? Would propably work better with a small coil
Yes. Some of the sensors do that.
INA226 can measure negative shunt voltages ie negative current.
You are right. My mistake!
@@AndreasSpiess no problem. Everyone makes mistakes unless they do nothing!
In future videos like this, could you include the approximate prices for the alternatives, please?
I leave links in the description to the source I bought them. Prices vary by country and by supplier.
@@AndreasSpiess Yes, and I can look them up myself, but it would be very useful seeing the price on the screen when you introduce each.
I've been battling with this current monitoring problem for a while now and still don't really have a solution after watching your excellent video. The INA219 can measure current in both directions, and operates at VCC 3.3v (even lower actually), however it is limited to max 3A current measurement. The ACS712 can measure higher currents, but only operates at VCC 5V, which is no use for ESP8266 projects. What I need is a current sensor that operates at 3.3v and is capable of measuring 5A or more bi-directional - so I can see when current is being drained from the battery or fed into the battery from the solar panel. Is there anything out there that can fulfill this?
The INA219 will measure any current you want. It measures the voltage drop across a shunt resistor up to 320mV. The fitted one is 0.1ohm , hence 3.2A. If you solder a second 0.1 on top of the existing, it will be .05 ohm and then will measure up to 6.4 A.
I agree with mahudson3547. Maybe you have to create your own PCB to accommodate higher currents
@AnreasSpiess If you remove the 0.1ohm resistor, the two terminals are just measuring voltage (high inpedance). So put high current terminals and shunt off the board and connect the two terminals with hookup wire to either side of the shunt. Almost any current you like and no new circuit board.
@AndreasSpiess - just thinking… If you take the shunt off the INA219 board so it becomes a voltmeter, you could also use matched voltage dividers on the terminals to allow for more than 26V. The current would be multiplied by the divider ratio? Calibration in the micro would be easy.
The ina226 can be used both on high and low side.
You are right! My mistake.
I want to measure mains current and direction. I've been told I need to put two inductors in quadrature to determine...what does that mean? Possibly a future video?
I put a link to my video on AC sensors in the video description.
@@AndreasSpiess Thank you Andreas.
in my opinion one more chip( ADS1115) can use as currert meter in positine or negative power cable.
General this I2C chip include
1)4 positive analog inputs with PGA in 16 bit ADC
In PGA have 6 range
A)PGA: +/-6144 mV Resoultion: +/-187.5uV
B)PGA: +/-4096 mV Resoultion: +/-125uV
C)PGA: +/-2048 mV Resoultion: +/-62.5uV
D) PGA: +/-1024 mV Resoultion:+/- 31.25uV
E)PGA: +/- 512 mV Resoultion: +/-15.625uV
F) PGA: +/-256 mV Resoultion: +/-7.8125uV
2) alert output pin for high voltage in analog input
3) differential mode convert 4 Analog input in 2 differential channels
channel 1 (ADC 0-1)
channel 2 (ADC 2-3)
================================================================
Then use differential mode
ADS1115 analog input MUST be between 0 and the ADS1115 supply voltage
================================================================
if connect in posstive power supply cable the max range is the power supply of ADS115
if connect in negatige power supply( ground point) the range is larger because the voltage in
resiston is very smail.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
My design i use 2 differential Channel with R0.05/10W connect to "negative"( ground point)
to get resoultion in six range's
1)PGA: +/-6144 mV Resoultion: +/-7.5mA => 245 A
2)PGA: +/-4096 mV Resoultion: +/-5mA => 163 A
3)PGA: +/-2048 mV Resoultion: +/-2.5mA => 81.62 Α
4) PGA: +/-1024 mV Resoultion: +/- 1.25mA => 40.96 Α
5)PGA: +/- 512 mV Resoultion: +/-625uA => 20.48 Α
6) PGA: +/-256 mV Resoultion: +/-312.5uA => 10.24 Α
keep mind with 10W resistor max current is about 14.14 A
so for safety limit is 10A.
with 50mV MAX loss of Voltage in resistor
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
I agree. You can use all ADCs to measure current using a shunt (as you did).
Good info... BTW...There in no 'W' in "circuit". The 'U' is silent....😉
what would you use for 2x 100W solar panels with 20V (running parallel)? I get max 10A. Can I use a i2c board???
You have to use a shunt resistor that is compatible with your needs. Maybe a custom PCB?
@@AndreasSpiess but as a newbie a custom pcb is so hard to do - or rather (too) easy to make mistakes
I have several INA219 boards but they are only rated @3.2A making them unusable for solar which can run up to 10Amps (in my basic setup case).
I am a bit confused over that issue.
You can change the shunt resistor…
@@mahudson3547Stronger: one must do that. The data sheet states the bit size for shunt voltage measurement is 10 μV. Also, the ADC resolution is given (12-bit ADC). Also, the full scale voltage range for the current sense input is ±320mV (at the PGA /8 setting). So, you can derive all the parameters needed for the shunt to be able to measure the current in your range of interest.
I agree with piotrswiatkiewicz3259. You probably need a custom PCB to deal with higher currents.
@@AndreasSpiess Dear Andreas! What does PC mean in your response? Oh... possibly, a custom PCB. That would make a lot of sense :)
By the way: @zyghom below proposed another of the TIs products: INA260. It has a built-in shunt ..... only 2 mΩ(!) which is nicely manufactured to work well with the rest of the circuitry (I am deliberately holding short of saying: calibrated). The chip is rated up to 15A.
I=UxR isn't right Andreas! U/R is what you meant! A neat video is so much more human with the odd slip-up. We know we're not being bamboozled by AI!
You are right! (I put the correction in a pinned comment).
Use piecewise linear interpolation to calibrate your values.
//used on esp32
// Coefficients for the piecewise linear interpolation
//Raw ADC value's
float coefficients_ADCread[] = {2 ,149,270 ,363 ,452 ,550,637, /* Add other ADCread values here */};
// corosponing mA measured externally
float coefficients_mA[] = {3.2,8.3,12.3,15.3,18.3,21.4,24, /* Add other mA values here */};
float convertToMilliAmps() { // Read ADC and convert to mA
adccounter=0;
ADCread=0;
//take 1000 mesurements for more avarige value
while (adccounter coefficients_ADCread[index]) {
index++;
}
if (index == 0) { // Ensure the index is within bounds
index = 1;
}
else if (index == sizeof(coefficients_ADCread)) {
index = sizeof(coefficients_ADCread) - 1;
}
// Perform linear interpolation within the segment
float mA = coefficients_mA[index - 1] + (ADCread - coefficients_ADCread[index - 1]) * (coefficients_mA[index] - coefficients_mA[index - 1]) / (coefficients_ADCread[index] - coefficients_ADCread[index - 1]);
return mA;
}
void setup(){
analogSetClockDiv(255);
analogSetPinAttenuation(35,ADC_11db);
adcAttachPin(35); //Analog read pin (pin 7 IO35)
}
void loop(){
Serial.print(convertToMilliAmps());
}
This is a very sophisticated program! Thanks.
Does anyone know of an open source equivalent to the Emporia energy monitor? It has up to 16 clamp-on current transformers to monitor home energy usage. It must use an analogue multiplexor to service so many inputs rather than multiple ADCs - but I have no experience with analogue muxes…
open energy monitor
I also put a link to my video about AC sensors in the description.
@@AndreasSpiess Thanks!
Thx
You are welcome!
Why is there a potentiometer on the board of the WCS1800?
It can change the threasold level for a digital pin
@@AndreasSpiess Thank you
Isn't there a Hall sensor in the ESP32 also?
Yes. But how would you use it for this purpose?
@@AndreasSpiess You're the teacher. Just here to learn ;-)
I once took a look at it but just for current detection, not measurement.
I think it was even possible but not straightforward to wake up the esp32 from sleep in response to changes in the field.
I missed the popular PZEM 004T in your lineup. For anyone using this sensors i am interested in your experiences. Cheers.
These sensors (and explanations) are mainly for DC. I left a link to a video where I covered AC sensors.
2:54 Do you like your multimeter? Have you reviewed it previously?
Yes, I like it, and I have it for a few years now. I do not do reviews on multimeters (not so important for me).
Evening Andreas, summer holidays I know. It is freezing here.
Here it is ok. Not too hot and not too cold. Lots of cycling ;-)
The big hall sensor board is bad for mains as it has copper fills up along the side of the chip. This reduces insulation.
This video is about DC sensors. I made another one about AC sensors
The ina3221 realisation is not good. The channels has crossover error.
You put your restisor divider in the beginning of the video on the wrong side of the sense resistor. The divider would only measure the supply voltage which should remain constant. I got what you were trying to show though but it should have been on the other side of the sense resistor so you would be measuring the drop rather than the supply.
I agree. My drawing is misleading. You need to measure a second time on the right side of the resistor to get the difference (as mentioned in my text).
Nothing appeared in the top right corner for me
Thank you for the input. Indeed, I forgot to add the link :-(
Very nice test. For ACS712 you must change those green connectors, they melt after 10A. Plus a smoothing algorithm will give you a great improvement👍
Thank you for sharing your experience!
Why the Reupload?
Because it is summer break (as said in my last video)
15:27 wrong. some of them can measure reverse currents, for example ina219/ina226.
You are right. See my pinned comment
Why this old video again?
As written in the comment and announced in my last video, I always show old videos during my summer break. Viewers asked for that, and according to the many comments here, a lot of newer viewers did not see the initial version. You seem to be a longtime viewer, though.
There is a typo at 1:40
You are right!
Analog measuring devices measure currents and then the voltage via the internal resistance.
Digital measuring devices measure the voltage and then the current via the shunt.
Others measure the magnetic field and thus the current.
The analogue input of the ESP8266 is not very good and is disturbed by the WLAN.
🌟🌷🌟
No, there is mal so garnix appearing in the top right corner....
???
@@AndreasSpiess Ich meinte der angekündigte Link zum anderen Video ist nicht da, wie behauptet 🤣
@@Gorkilein Aha. Dann habe ich ihn vermutlich vergessen 😞
no video in top rtight cortner.
You are right. Now it should be there. My mistake.