Build a high precision circuit for charging/discharging Li-ion batteries

I'd like to build a high precision circuit for charging/discharging Li-ion batteries with the ability to monitor current, capacity, voltage, and temperature versus time. The circuit should have the following characteristics:

1) Ideally powered from the 5 V pin on a Raspberry Pi (this is somewhat negotiable)

2) Can charge a battery to 4.5 V and discharge to 2.5 V (discharge to 0 V is better)

3) Have constant current (CC) and constant voltage (CV) mode capabilities where the circuit switches from CC to CV at a programmable user defined voltage. For example, the circuit would do constant current charging to 4.2 V, then hold at 4.2 V for a period of time, then discharge to 3 V, and repeat. I suspect the circuit will look something like this : Figure 1 at [url removed, login to view], but it does not need to

4) Constant current is programmable (e.g. using a Raspberry Pi, python, i2c and a DAC). Ideally the DAC is an MCP4725 ([url removed, login to view])

5) Constant voltage is programmable (e.g. using a Raspberry Pi, python, i2c and a DAC). Ideally the DAC is an MCP4725.

6) In constant current mode the current does not vary by more than 0.1%

7) Current range of -100 to +100 mA. Being able to both sink and source current is important (e.g. discharge/charge)

8) In constant voltage mode the voltage does not vary by more than 1 mV

9) Programmable voltage range of 2.5 to 4.5 V (ideally 0 - 4.5 V)

10) All components can be tested on a bread board (e.g. no surface mount components unless they can be found on an inexpensive breakout board like the MCP4725: [url removed, login to view])

11) Voltage measurements (e.g. ADC) are made with an ADS1115 ([url removed, login to view])

12) Current measurements are also made with an ADS1115 across a shunt resistor with minimal resistance drift and low temperature co-efficient. Must be able to read negative and positive currents (e.g. charge/discharge currents). Shunt resistor should be in series with the battery immediately in front of, or behind.

13) To accomplish above accuracy I assume a voltage regulator/shunt is required

14) Complete bill of materials

15) Circuit diagram and PCB design done in ExpressPCB software ([url removed, login to view]) including a Raspberry Pi header with male/female pins (e.g. so the board can be mounted directly to a Raspberry Pi and all pins are still accessible). PCB layout should include mounting holes so the board can be secured to the Pi using standoffs. Also PCB should not be larger than the Raspberry Pi 3 board in width or length

16) Description of how the circuit operates

17) Reasonable amount of technical support during building/testing

Miles Stones:

1) Circuit Diagram (35%)

2) PCB Express design with BOM (35%)

3) Working circuit (bought, built and tested by me) (30%)

Skills: Circuit Design, Electrical Engineering, Electronics, PCB Layout

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About the Employer:
( 2 reviews ) St. Croix, Canada

Project ID: #12612817

22 freelancers are bidding on average €734 for this job


hi, i am an electrical engineer. i have expertise in embedded system design and Matlab.i can help you with this project. Kindly reply back and let us discuss project further then i can prepare a detailed work proposal More

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Hello. I'm an electrical engineer / PCB designer. You may check my qualificationin the profile. We can discuss any details in the chat (it will be a challenge to achieve desired tolerance). Will do my best. Viktor

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Hi, I am a post graduate power electronics engineer and having very good experience in product design and development. I am excellent in embedded programming using pic, dspic controllers and MATLAB codding for Power p More

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Hello, Have a great day. we will ship you fully working hardware and we will take care of ROHS compliance. Please feel free to contact us. Best Regards, Shahbaz.

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Hi, I have more than 12 years of experience in embedded system design and development and i have a team of web and mobile application development with more than 6 years of experience. I have attached some of links her More

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Hi sir, We have designed many projects in which we used battery management, we have read your project and ready to offer you our solutions at very low and affordable rates. Please discuss with us, we assure you the More

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Hello I have used these ADC and DAC many times for digitally controlled power supplies but not with RPi, probably you are using RPi for other purpose and this is a kind of add on. You will need a Adjustable Regu More

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Dear employer, I'm an electronics engineer with more than 4 years making product for customers around the world. I have experience with Raspberry Pi, MCUs, ADC/DAC and Power Supply design. I can also design the schem More

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i am an Electronics Engineer with MS in Electrical Engineering. I have done many hardward and software projects related to this field. I have written 4 international research papers and one of them is related to power More

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FREELANCER RECOMMENDED ------------------------------------------------------ Can help... I am an Expert... Lets Start! Please start a Discussion with me and we can get started from there... Please check the past p More

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Hello, I'm interested in your project, I'm sure I can deliver quality work, Are you looking for a cheap developer or Educated and experienced [login to view URL] my profile and read my feedback. I'm ready to start your pro More

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Hello, Istvan here. [login to view URL] I have years of experience working in matlab, python, electronics, pcb, fpga. I am good in algorithms too. Some of my previous projects : eye tracking in matlab, analysi More

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