The current through the voltage divider should therefore be at least 2000 * 50nA = 0.1 mA. Glad to see it will happen!

Since we're gonna have to get them remade anyway, we can incorporate those changes into the opampwhile we're at it. Current must be measured by either shunt resistors (invasive) or hall effect sensors.

From automation in big factories handling bread, dough, fish, meats and vegetables to the living room and universities where they still can grip everything you throw on them and still be squishy and safe to be around for students. RoboCup is the largest scientific annual event to advance A.I., robotics and automation in the world. These calculations will also be suitable for 1/2 Watt and 1 Watt resistors. Microcontrollers work on 5 or 3.3 volts(From here on we will take in to consideration 5 volt, techniques listed below can also be applied to 3.3 volt microcontrollers). JavaScript seems to be disabled in your browser. What does "Check the proof of theorem x" mean as a comment from a referee on a mathematical paper? The demand for PPE exceeded the supply available from traditional manufacturers and a rapid solution was needed. Solar charge controller also output voltage approximately equal to 15 volts to charge the batteries. Please enter a valid email address. We just received the PCB boards in the mail and and already found a minor issue with them: the pads for the DCDC supplies are flipped from where they should be (at the opposite edge of the part than where they belong). A. The problem with optocouplers is its hard to configure them and they require more effort than voltage divider. It only takes a minute to sign up. How can I get an AnyDice conditional to convert a sequence to a boolean? The technique is to measure the voltage across high potential battery first, than against the lower ones and negating the subsequent batteries voltage from the one at higherpotential. However, it's quite conceivable that at some combination of parameters (inter alia temperature, clock speed, supply voltage) 10 k is a critical limiting value. First i short circuited the 2 batteries and it cost me much at the end i finally fixed the code and inserted some delays which increased the hardware efficiency. The design of any voltage divider also depends on the input impedance or load imposed by the ESP8266. like a circuit (from AliExpress) or using some other component that would be greatly appreciated. How can we determine if there is actual encryption and what type of encryption on messaging apps? And from that, I'd considered that with a source impedance of 10 k or less, the measurement error from that source would be in the order of LSB or less, i.e. Most importantly, we would like to measure the balance of current in the three major branches of an off grid system: the Solar (always positive), the Load (always negative), and the Battery (+/- depending on the other two). If you have any more method in your mind please let me know about it. Now lets calculate the values for Rtop and Rbottom. Check out our engineering forums, Getting started with MicroPython on ESP8266, How to use MicroPython with ESP8266 and ESP32 to connect to a WiFi network, Using MicroPython SSD1306 driver to interface an OLED display with ESP8266 & ESP32, How to use ESP8266s sleep modes in MicroPython, MicroPython: Time-related functions, timers & interrupts in ESP8266 and ESP32, MicroPython Reading analog signals in ESP8266 and ESP32, ESP8266/ESP32-based WiFi access point using MicroPython, How to achieve longer MCU battery life with low power sleep mode, Infineons CoolSiC devices support Deltas bi-directional inverter, Qualcomm and Mahindra to provide immersive in-vehicle experiences, Diodes launches high-efficiency synchronous boost converter, Help designing 1.6KW Isolated AC/DC with Constant Current Output, Help with Zero Crossing Detector with the 16F877A code on MPLAB XC8. So battery-2 is supplying 13 volts in series string array. Since we had to make a minimum of 6 of them, we have 4 more available for sale (fully assembled)if anyone is interested. Forum has moved to: https://community.openenergymonitor.org. With the new TurtleBot 4 Mobile Robot coming soon this fall, the next-generation robotic platform for learning the Robot Operating System (ROS), it's more relevant than ever to take a look back at how the TurtleBot came to life. Click the below button to take the tutorial. e6)EIgf"{lf||U7$8GzR'F5'_)F]TH_rGetd|lF hV23dp",5g;p~Y7U?K This is because we used high value resistors in our divider to minimize the wasted power. 1/4watt or 1-2% etc, I'm new here but know there are many types) and values that I could read with A0 (analog pin, max 5v). Analog multiplexers can also be used instead of relays. Its obvious from the above discussion that the voltage across Rbottom will not exceed 5 volts now. So while, dBC, your result falls within my definition of "several times", I restrained myself to "well in excess". Measuring string array of batteries voltages using arduino, The circuit seems to be pretty simple in diagram but their are some serious pros and cons. If the two relays accidentally switched on at the same time their will be a huge blast due to short circuit of batteries. 4 to 16 multiplexer is used to drive 2 ULN2003 drivers. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Only one analog channel of microcontroller is required to measure multiple batteries. Lets calculate it. Is Vcc the same as Vcc-? ethics of keeping a gift card you won at a raffle at a conference your company sent you to? For the sake of argument, let us assume the following The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media Privacy Policy | Advertising | About Us, Voltage divider voltage divided against two resistors, Voltage divider resistance value calculation, Voltage drop against resistances of voltage divider circuit, Series batteries combination voltage monitor by microcontroller, Optoisolated battery monitor with microcontroller, Series battery monitoring with microcontrollers. Optocouplers also increases the circuit cost. I selected one resistor Rbottom to be 10k ohm. We could use lower values, but the amount of current constantly passing through them would be a drain on the batteries. UL2003 input is connected to multiplexer output. 1) Are working within their wattage rating. This almost certainly meets the requirement of not significantly loading the battery. So based on the low end of the voltage range the divider chain should total in the region of 45V / 0.1mA = 450K ohms.

So it boils down to picking a pair of resistors that 47K Now if 18 volts are at battery side it will be divided across resistors, 5 volts drops at 10k resistor and remaining 13 volts drops at 26k resistor. You can find many tutorials on internet on how to do so.

please suggest resistor types (e.g. We know Vout can be up to maximum 5 volts since nodemcu works and accepts maximum 5 volts at its I/O pins. "A few days after sending off the board design" The battery bank voltage needs to be stepped down for input into the Arduino.

Similarly if battery-3 is at 23v. Now its a hard task to accomplish. Those digital input buffers are at their best when you feed them 0V or Vcc;leavethem floating (or feedthem an analog signal)and they start to suck current. The engineering intern who's been working on this designis on vacation and returns next week, but I'm trying to keep things moving alongso please excuse all the questions. I used arduino mega to monitor a cluster of 32 batteries with the same relay method. Would a 100K resistor connected to ground pull an open analog line down to 0. Nice project! Soft robot grippers are joining the industry! So their pins are also working on 5 volt TTL logic.

So lets go through the calculations to select good resistor values. Four 12 volt batteries are connected in series to output 48 volts. For example, Free shipping on orders over USD $ 100.00 *, Data Communication and Human Input Devices, Defense, Security, Surveillance & Inspection, * Subject to approval and not available for products shipped by others sellers through the RobotShop Marketplace, My order was quickly processed and shipped. Arduino relay is used in the project. well in excess of the 10 k recommended maximum. My silicone mold got moldy, can I clean it or should I throw it away? I just did a spot check on a random ATmega2560 I had handy. Voltage range to be measured = 40 - 65V We have an off grid 48V system here as well. This can also be used to power the Arduino, which is nice. But still their are some cleaver ways to do so. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Vin is 18 volts when the battery is charging(worst case scenario). In this post i am going to enlist some of the ways through which we can measure individual battery voltage which is a part of series or parallelconnected string/array of batteries. but with all values I have tried one resistor almost melts as soon as you connect to battery. Why is the comparative of "sacer" not attested? Battery monitoring with 3.3v tolerant microcontroller. Pin A0 can draw 50nA and this should not effect the measurement by more than 1 in 2048 (half the least significant bit of the ADC). But what about if we want to measure an individual battery connected to a cluster of batteries in series or parallel combination. Than 36v-23v gives 13v. Standard 1/4 watt resistors are going to melt when overloaded 10 times. Feeding them Vcc/2 causes them to draw significant current as it means both transistors are on (at least partially) providing a path from Vcc to GND within the buffer (the current draw isn't through the input pin). It outputs an equivalent voltage to input but with drop in voltage rating. So it would seem that "the Arduino's impedance varies while sampling, in such a way that the voltage divider's output will be affected. The higher the battery capacity, the longer it will run, but the more it wil Hi! Well a little more mathematics is involved here. For these boards the input range is 0 to 3.3V. However, we still need to measure the current of some additional DC loads that do not go through the inverter and we also need to measure the voltage levels of our battery bank. Than 36v-23v gives 13v. Can I use a MOSFET to connect the voltage divider just before reading the voltage? Ultimately, we ended up designing a custom PCB for the voltage monitor and sent the files off to OSH Park to have them printed. I made a simple diy project with the same above logic.

Closest equivalent to the Chinese jocular use of (occupational disease): job creates habits that manifest inappropriately outside work. Thats a 23volt range, so to maximize resolution we used a circuit simulator (LTSpice) and adjusted the feedback portion of the opamp to find a configuration that gives us a linear output from the opamp of 0.6V to 3.0V for a 42-65V range. For the same reason, always enable the pull-ups on unused pins. Thanks for contributing an answer to Arduino Stack Exchange! it would not be significant. See http://www.maximintegrated.com/en/app-notes/index.mvp/id/1957. I'm watching this too! Nodemcu Arduino ide is used to write, compile and download the code in nodemcu WiFi module.

So far this article has been helpful, it talks about a voltage divider with a opamp to get more accuracy, but I need a bit more advice from someone that knows more than myself. ie the minimum that R1 + R2 should equal is 50k. Have a technical question about an article or other engineering questions? Now how to measure voltage of individual batteries connected in series. I've built a circuit to measure DC Voltage with full galvanic isolation using the HCPL-7520, and an Isolated DC-DC Converter to supply power to the isolated side, only pencil diags thus far, so will post more details later once I have done formal schematics. The battery bank voltage swings from 42V minimum when they are almost empty to 65V maximum when the batteries are being equalized. This half voltage is feed to microcontroller to measure the voltage. Pros. If all goes well, we'll proceed to work on the Hall effect portion of the design. I would like to monitor the battery voltage of a 48v solar battery system. 2.2K That said, any other thoughts about the design that could be improved or tweaked? The major differences between this and the standard Emon setup: So far weve spent the majority of our effort working on the voltage monitoring portion. Double pole single through relays with batteries and microcontroller connections are shown below.

The circuit seems to be pretty simple in diagram but their are some serious pros and cons. First i short circuited the 2 batteries and it cost me much at the end i finally fixed the code and inserted some delays which increased the hardware efficiency. [op-amp isolation just means current/voltage isolation, not electrical isolation like with an optical isolator] We decided to use a Texas Instruments LT1013CP opamp. Marketplace sellers offer different shipping options. Heres how people can take their projects from design to completion. We can also offset these values so they better fit into the range of the Arduino's inputs.

Asking for help, clarification, or responding to other answers. Arduino relay battery voltage monitor connected in series, Car automation Battery Monitor, Engine Temperature, Head lights control, Battery monitor over WiFi using nodemcu WiFi module, Copyright 2022 WTWH Media LLC. The raw ADC input on the ESP8266 chip is 0-1V with a high input impedance (~20M). For example two 12 volt batteries are connected in series to build up 24 volts. Thanks for the additional information and insight. Connect and share knowledge within a single location that is structured and easy to search. 3) Draw an insignificant amount of current relative to the ratings of the solar panels. Lets play it safe and say that R1 + R2 is 100k. We modeled it in the software, and also with the online calculators but without the type of lab equipment you guys have it was hard to verify. We also added a 12v Supply to power a Hall effect break out board.

More like San Francis-go (Ep. All with email notifications. We added a capacitor on the input side of the circuit to filter out some noise and act as a local power supply to our DCDC converters. How can we send radar to Venus and reflect it back on earth? https://openenergymonitor.org/forum-archive/node/11011.html.

An extra power some time is also needed to power the optocoupler. Announcing the Stacks Editor Beta release! With an opamp we can focus on the 23 volts that really matter and increase our resolution. As long as that limitation is understood and is acceptable, and it is being used at low voltages only, that is probably OK.

Since the resistor values are fixed we can calculate the voltage ratio across the resistors with respect to the source and use it in code for actual voltage at source. Are you able to quantify the effect that lowering the driving impedance to a few tens of ohms had on your readings? Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. Amplifier may also be needed at end to amplify the voltage output. Otherwise, they look great. Circuit may also be messy. I have a few ESP8266 devices, all analog pins can take up to 5v but I think in reality the A0 (ADC) should be max of 3.3v (see. Order confirmation and Order shipped emails are the same day or next day. A1) Thats actually quite a long runtime for a skid steer robot. Wow thank you so much for a great explanation. However, if you are interested, a op-amp circuit can be built from a 741 IC (among others) and is configured like this: It sounds as if you have tried using far too small a value resistors. But if for any reason the battery negative is not earthed, then you have a potentially dangerous situation. How to tell reviewers that I can't update my results. The 0V pinspiked to just over 600mV as it was selected, and then decayed back down to 0V about 3 usecs later, well within the 12 usecsallotted. Each relay must be properly switched on and off one by one. The input voltage that will generate the full scale 10 bit encoding (1024) may well be different. Hi @PeterJennings , I have tested the boards I have, they read max input (1024) at 3v (not 3.3 like the specs say) so I'll adjust accordingly, thanks. Considering thatthe opamponly cost $2.65, it seemed like a safe route to go with some additional perks along the way. The link is below. Robot and AI waste management technology helps produce responsibly made recycled products, reduces waste and builds a cleaner, healthier world. Note: Most ESP8266 development boards come with an internal voltage divider. Let's simplify. During charging battery voltage can increase to 18 volts.

Referring to the ESP8266 Community Forum the analog input imposes a 50nA load, but they also state that the maximum input voltage is only 1V (equivalent to 20 M ohm impedance). Junior employee has made really slow progress. User can see the battery status now on smart devices like mobile and desktop computers. Help understanding several components in the sch of eMonTx 3.4, http://www.maximintegrated.com/en/app-notes/index.mvp/id/1957. The question now is how the 3.33 volts is converted to 12 volt by nodemcu or how from 3.33 volts we can predict that at the battery side the voltage is 12 volts. A typical ADC clock rate is 125kHz, so a conversion takes 104 usecs, the first 12 usecs of which is charging the cap. Digital pins of microcontrollers are required to activate the relay coils and for individual battery an individual pin is required. How is making a down payment different from getting a smaller loan? For example for the above circuit the measured voltage across battery-1 is 48v and battery-2 is 36v. That drops to 42.6mAafterenabling all pull-ups. They will draw a maximum of 65V/(360K + 5K6) = 0.18mA and the 360K resistor will dissipate about 10mW. When I'm working in an area of knowledge outside my core competencies, I tend to rely on best practice methods and in researching this came across countless examples of opamps being used to fix the effects that sampling may have on a source.

Anyone can build a robot with the right steps. In parallel combination voltage across each battery remains same. Were selling off the extras for anyone thats interested. RobotShop is also a leading force in Robotics Education & Research. At 50 volts its capable of passing 15 Watts of power to our little PCB, which is more than enough for our board but low enough to protect the input traces from bursting into flames. Here we need some important considerations to be taken seriously. These are some of the ways through which batteries connected in series or parallel can be monitored. My test above was just performed on a single part, and the ADCinternal series resistance can varyanywhere from 1K to 100K. 2020 RobotShop inc. All Rights Reserved.Putting robotics at your service is a trademark of RobotShop inc. Hi @smurphy0620 welcome to the RobotShop Community. Can anyone suggest a way of reading high DC voltage (40-65v) with and Arduino (really I'm using an ESP8266)? Maximum input voltage of pin A0 = 1V Note: For the above circuit the resistors values should be selected using the same formula given above. Both are adressed in the link posted by VE7JRO. - I would like to have 45 to 60 minute runtime and replaceable if practical. See the circuit below. Your Vin is 60V and Vout is 3.3V , Assume R1 and R2 have same value, then calculate the values of R1 and R2 using above formula i.e. Arduino Stack Exchange is a question and answer site for developers of open-source hardware and software that is compatible with Arduino. Finding a suitable multiplexer and its configuration is as difficult as of optocoupler. Note that the proportions of both resistors define the voltage level for the analog in while the sum of both resistors are relevant for the current. To correct this, we feed the output of the voltage divider into an op-amp. Nodemcu esp8266 WiFi module is used in the project. Our hardware includes 8x Trojan T-105 6v Batteries (~10kWh capacity) in a 48v series configuration, an Outback VFX3648Inverter, an Outback FM80 Charge controller, and 2,300 Watts of Sharp brand solar panels mounted on our roof. I am also going to add some margin above the 65V max that the solar panel can output (plus it makes the math easier). It's always like that! It also has the longest history of robot competition since 1996. Referring to standard resistor values, 360K and 5K6 in series will be very close to 64:1 (64.28:1). This ratio is utilized in code for predicting the actual source/battery voltage. The pcb layout also restricts it to low battery voltages, and it will not be possible to use it - even leaving off the dc-dc converters - on higher voltages because of the minimal creepage distance between battery positive and GND (= battery negative). We'll write a follow up with a bill of materials and the design files. Project contains free source code and circuit diagram. Also do isolated DC Current measuring with the ACS 758. The "TurtleBot" might have the name of one of nature's slowest creatures but make no mistake, this powerful piece of equipment represents a rapid leap forward for robotics development.

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