Battery Analyzer for Electric Vehicle

[ashoksam]

Dear Sir/Madam, 

We want to design a Battery Analyzer for Electric Vehicles such as Plugin Hybrid car(PHEV), EV passenger car,Heavy delivery van.The battery voltage can be the range of 9 VDC to 800 VDC. Please suggest us a appropriate part or design which can measure the following parameters: 

1. Voltage,Current,Temperature 

2. State of Charge(SOC) 

3. State of Health(SOH) 

4. State of Power(SOP) 

5. State of Safety(SOF) 

Regards, 

S.Ashok kumar 

Threshold Software Solutions, 

Hyderabad,India. 

Ph.no: 9985979212 

[Hooovahh]

What you are asking for is a bit too nebulous.  That is like saying, I am a doctor and want to know what equipment I should buy to measure the health of a person.  The answer isn't going to be a single device, it can't be and you need to know the history of the patient.  The health of a battery is most often estimated by keeping track of how much watt hour throughput there has been in the life of the battery.  Along with things like how many large charge/discharge pulses has there been, and how often has the battery been charged or discharged to the extremes.  And maybe how balanced the cells are.  This all goes into what is SOH, and is going to need to be a thing that is tracked with the history of the battery.  Then there is the rated capacity versus the actual capacity.  For this you'll need to do full discharge, and then a full charge.  Of course most batteries don't like doing a full charge and discharge and will protect themselves by opening the contactors early.  All of these checks typically go into a battery management systems (BMS) that go with the pack and keep track of this.  What about the health of the contactor?  Has it been opened or closed under load?  How much load?  How often?  All of these things are tracked by the pack and all you usually need to do is ask it.

Reading the voltage and using a look up table for OCV measurements you can get the SOC assuming no charge or discharge has occurred recently.  If it has you'll need some kind of algorithm to estimate SOC.  Again this is typically part of the BMS.  Outside of that I'd recommend a DMM for this because they come with large common mode voltages and will likely be needed for reading cells when the ground plane has shifted.  Otherwise you may burn up a DAQ card.  These can also do current readings, but I've also seen voltage shunts used and then have that go through a signal conditioner, then read with a DAQ card. 

As for temperature you'll likely need a thermocouple or an RTD reading device.  If you are looking to measure the thermistors on the battery already you'll need to buy the right equipment for the sensor type.  But again a BMS should be there and you should be able to just ask it.

[S.Nishizawa]

Hi ashoksam

Thank you for reaching us.

As far as I hear your story, also referring to what Hooovahh says, I cannot judge whether we do or do not have a product which suits your needs perfectly.

I assume it ’s better to consult with the sales engineers in your country, because you would want to build your own system for your project.

Contact number below:

+ 91 80-4119 0000

Best Regards,

Shinsuke Nishizawa

Applications Engineer

National Instruments

http://www.ni.com/support