NI-9205 for Battery Pack Monitoring.

[RobbieD]

HI, please excuse the basic nature of this question. Don't want to get the configuration wrong...

In the specifications for the NI-9205, there's the following line...

'Each channel must remain within ±10.4 V of COM'.

I need to measure cell voltages from a battery pack with 8 cells with a maximum voltage of 4.2V per cell.

So if I was to configure the inputs of the card so that each differential input would measure a cell voltage with respect to voltage of the previous cell (Cell2 w.r.t Cell1) , would the card only allow a maximum of 2 cells to be measured, or is the +-10.4V range centred around the common mode voltage for the inputs?

If only 2 cells can measured for this application, does anyone have any recommendations as to how to achieve this using a cDAQ chassis.

Many thanks

Rob

[santo_13]

I remember a company developing a C-series card just for this purpose; if I find it, I will update this post.

Here you go - https://www.wireflow.com/products/io-modules/c-series/wf-3169-battery-stack-monitor-module/

[RobbieD]

Hi Santosh,

Many thanks for your reply.

The card looks like just the ticket, but does not support cDaq Chassis at the moment. This is what we currently have to work with.

Cheers

Rob

[santo_13]

My bad, I missed that you need something working with cDAQ as only NI's modules work with cDAQ as it needs to be compatible with NI DAQmx drivers.

[rolfk]

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@RobbieD wrote:

Hi Santosh,

Many thanks for your reply.

The card looks like just the ticket, but does not support cDaq Chassis at the moment. This is what we currently have to work with.

In that case you would need to use an analog input module with channel to channel isolation. And yes I know that will get VERY expensive very fast. For your 8 cells you might have to use 2 NI-9239 which will set you off for 4000 bucks. An NI-9221 might also work because of its 60V input range but it is single ended, so you would have to calculate the individual cell voltage by subtracting the different analog input values. And the NI-9228 might be your best ticket for the task at hand. It offers 60V input range which is rather high for your use case, but fully isolated differential input channels.

NI sold (and maybe still sells) a C Series module developer Kit that allows third parties such as Wireflow to develop and sell their own C series modules. But that Developer Toolkit only supports developing FPGA based solutions and not to plugin the modules into the DAQmx framework. So third party modules supporting cDAQ is a pipe dream.

[RobbieD]

Hi Rolf.

Many thanks for your detailed outline of the available options. Much appreciated.

Cheers

Rob