Isolated high voltage & isolated current shunt based on ADS1115

[pprasse (Patrick Prasse)]

Dear all,

I made an isolated high voltage (up to 850V) and isolated current (+/- 200A) shunt and is based on the original diyBMS-Currentshunt: GitHub - pprasse/diyBMS_CurrentVoltage_ADS1115: Isolated current and voltage sensor for up to 850V based on ADS1115 and attiny1614
Maybe the project is useful to someone.

The current measurement uses an ACS758ECB-200B hall-effect based current sensor IC.
The voltage measurement is isolated using an ACPL-C870 Precision Optically Isolated Voltage Sensor.
The analog signal from both measurements are converted using a ADS1115 16 bit ADC.
Coulomb calculation takes place in using an attiny1614 and communication uses isolated RS485 / MODBUS.

The hardware is finished and firmware is ready for testing in a real battery pack.

If you have comments, let me know.

All the best,

Patrick

[Chris87 (Christoph Kastl)]

Hi Patrick,
I’m working on a similar project, just for my different PV-Strings. I’m using the ACS758…-50U and also the ADS1115. After the 1st tests, I’m not quite happy with the results, OK for me the accurately is not that important, as I’m only comparing strings with each other.
For your case it would be essential to have a precise measurement, additional to that, I wouldn’t trust this small legs of the ACS to be capable of 200A.
But never the less, looks like an interesting replacement for the Shunt board for smaller applications.

[Andrew_Congdon]

@Chris87

I’m working on a similar project, just for my different PV-Strings.

I used PZEM-017 and a 50A shunt for each of my 4 strings with a single USB RS485 interface.
Rated for 300VDC. Cheap and simple. A little python to load the values in mqtt, done.