Adafruit will not be shipping orders Thanksgiving Day, Thursday November 22, 2018. Expedited orders placed after 11am ET Wednesday November 21 will go out Friday November 23.
0

Low Side Current Sensing with a Remote Shunt Resistor

The Salae Blog has a nice guide on low side current sensing using a remote shunt resistor.

I’m trying to finish up the PCBs for the boat this weekend and thought I’d share this little solution I thought was kind of neat.

Among other things, we need to measure the battery pack current, and fairly accurately   This is mainly so the BMS can keep track of the approximate battery state of charge — i.e. percent charge remaining.  To do this we need to measure the load current and the charger current all the time, and basically count coulombs in and out.  (There are some more sophisticated things you can do by doing calibration, tracking impedance and temperature but I don’t plan on doing any of that craziness for something like this.  There are some cool state of charge ICs out there as well, and you actually calibrate them with the cell you’ll be using.  Pretty cool.)

If you want to do high side sensing, we have two very nice sensors that do a great job!


Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, or even use Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for MakeCode, CircuitPython, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Join 8,700+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

CircuitPython – Python on Microcontrollers is here!

Have an amazing project to share? Join the SHOW-AND-TELL every Wednesday night at 7:30pm ET on Google+ Hangouts.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Follow Adafruit on Instagram for top secret new products, behinds the scenes and more https://www.instagram.com/adafruit/


Maker Business — Spotlight on Makeblock, one of the latest companies to find success in the STEAM market

Wearables — Emphasize the light

Electronics — Avoid serial confusion!

Biohacking — BDNF a Biohackers Best Friend

Python for Microcontrollers — Python powers costumes, and community @circuitpython @micropython @ThePSF #Python

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at AdafruitDaily.com !



1 Comment

  1. When I was developing Arduino-based lithium battery chargers for an electric vehicle lab course at Portland State, I used low-side current sensing with an op-amp at first and had a very hard time dealing with noise at those millivolt levels. Instead we used current sensing chips, in our case Allegro’s ACS712 series (Digikey link). A Hall sensor measures current magnetically from isolated pins, so you can put it anywhere, low-side or high-side. A nice analog voltage output proportional to current can be connected directly to an Arduino analog input. Very easy and accurate.

Sorry, the comment form is closed at this time.