Issues for galvanic isolation? (8 Batteries, I2C, PoE, Switch, 8 Arduinos)

Hi together,

I try to build up a monitoring system for secondary batterys (36V 13Ah, Lion). My plan is to monitor every battery via one Arduino through I2C (Battery Managment System) during charge and discharge. The Arduino is powered and connected to a PoE Switch which is connected to different things. There are up to 8 Arduinos/Batteries with one PoE Switch at the same time.

I'm still uncertain about the galvanic isoltaion or the isolation in common. I have read that the Arduino Ethernet PoE Module should support 1500 V Isolation. But also I have read that some cheaper Switches dont isolate each channel from another.

Also thinking about to implement Silicon Labs Si8400AB in order to isolate the 5V-I2C-Arduino from the 36V Battery.

Has anyone some suggestions or concerns?

Also thinking about to throw my whole idea/project into the trash and start doing some USB-Serial-Solution.

Would totally like to hear your point of view?


You have to provide more information about your project. Post at least a drawing of the schematics, links to the datasheets of the involved Battery Management System and other documentation. In most situations a galvanic isolation isn’t absolutely necessary but the battery’s datasheet should provide that information.

More information? ... hmmm ...

First of all, I dont think there will be a problem. But who knows?

So: I'm very interested in testing ebike batteries. A few friends and family members have the same type of ebike batteries (36V 13Ah). I opened a used one. There are 50 cells of Samsung 26F Lion cells in it.

BMS was a blind flight used the "Technical reference Manual" of bq20z80-v110 + bq29312a Chipset . But some SMBus functions aren't identical. So don't know if its the right chipset.

I am also interested in the same thing. I see your post is from July, but maybe others would be interested.

I just found a link to a board called Linduino. It is made by Linear Technology for their demo / evaluation boards. I haven't had the time to look very much into it, but they say:

" ...
The Linduino Uno is a Arduino Uno compatible development board, with a twist, it comes with a LTM2884 uModule that provides full USB isolation.
... "

I cannot find anything on that module. But the user manual with schematic is here