Battery Testing Equipment Recommendations?

C

ChopperMan

10 W
Joined
Aug 20, 2007
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81
Location
Essex, UK.
Hi All,

In the coming weeks I will be building some rather large LiFeBATT packs. 50S2P 150V 20Ah for a project which will be announced in February or March.

We are designing a charger and a 'load' for testing but we want to record volts, amps, Wh's consumed etc, during the cycle testing. Is there any off the self equipment with PC/Software data logging that can do this?

This isn't going to be a one off use so I am prepared to make a far financial investment to get something that is user friendly and flexible. In future I expect to be testing packs from 36V 10Ah up to 300V 300Ah with loads up to 400Amps.

Many thanks,

Ian
 
To do great battery test some very good RC charger could be greqat for you if you stay under 60V but for 300V and 400A it's a different game!

I'm sure higher power battery tester would'nt give you the same accuracy if used with lower power like RC charger...

I think the best way for you could be to use labview with great I/O interface and some NI DAQ programs that already are distributed on the internet.

Also, the The Cadex C8000 Series Battery Testing System could be a good trade off.. it's just the price that could be :shock: ...

personally i've never seen battery testing system that can test over the megawatt of power like 300V 400A.. but certaionly it would cost you undreds of thousand dollars!

Doc
 
Thanks guys, I'll pass these on to my engineer. My experience comes from using a Cycle Analyst and its only that basic information we need, but recorded on a PC. Labview and Cadex seem overkill, some simple V & A graphs to track voltage sag for a given rate of discharge and total Wh discharged would be enough for the majority of projects. However, there is a Labview representative only 40 miles away so I'll get some more info.

These packs will be used in electric vehicles ranging from a small hatchback to a 3.5t delivery vehicle. Also, a marine propulsion system. It's mainly to test the prototype packs and ensure they meet customers performance specs, before delivery, so breaking them down into smaller more manageable modules isn't an option.

I have been having some very interesting conversation with OEM's. There will be at least two low volume electric cars coming out of the UK in the next 18 months. One will be available as a kit 8)

Ian
 
Hi Doc,

I've got the 'Big Load' covered and I will see the Labview rep next week. Can you recommend a ni daq card for the job, I'm having trouble as they all seem far too complicated for this application.

Many thanks,

Ian
 
ChopperMan said:
Thanks guys, I'll pass these on to my engineer. My experience comes from using a Cycle Analyst and its only that basic information we need, but recorded on a PC.
Ian
Click to expand...
You might check with ebike.ca about connecting the Cycle Analyst to a PC. Microcontrollers like the one in the CA are designed to talk to a PC for programming and setup. There's a chance the CA may do what you want already, or be easily modified to do so.

Richard
 
The price is hard to beat on this one:
http://www.eagletreesystems.com/MicroPower/micro.htm

New model goes up to 70v and 150 amps. They also have a variety of additional sensors you can add.

Here's a screen shot:
micropower-graph.gif
 
What a great product! Would be great on a Motorcycle, if only they doubled the current capability! Think i'll get one for battery testing in the workshop.
Where did you get your "big load" from Ian?

Steve
 
Here is a possible solution:

http://labjack.com/

The LabJack is a DAQ (data acquisition) device, with digital and analog inputs and outputs.

It connects to any USB-equiped Windows, Macintosh, or Linux computer. The drivers support many popular programming languages. I've operated mine using Microsoft Excel spreadsheet macros.

There are both stand-alone boxed versions for experimenters, and OEM bare boards for building into new products.

Good luck on your project!
 
Very suprised that nobody mentioned using a HP4328A Milliohmmeter to measure the internal impedance of batteries .
Without knowing this parameter , it is next to impossible to determine a safe charging or discharging of the cells
To give everyone a feel for number , the A123 cell have impedance in the order of 5 to 8 milliohms , the panasonic HH650D " D"
cells Nickel Metal Hudride rated at 6.5 A/H have impedance in the order of 2 milliohms ,have some that are down in the 1.8 region.
Can easily extract 300 Amps .sure they get hot ,(180Watts) but they are discharged in about 1 minute .
Impedance is a true measure of a cell quality the lower the better in all respect .
 
Hi Richard, We already use a CA and record data manually be this requires someone to watch the thing and is very labour intensive.

Hi Steve, Ray, my engineer has sorted that out, I'll pass on the details once we have tested.

Hi disadvantage, thanks for the link, I will have a look at this. Their forum has given me a couple of ideas for software too so thanks.

Hi apheonix, We already know the cell spec (12C continuous discharge, 3C charge, 6 milliohm impedance) as we are the manufacturers representative in Europe, the bench testing system we are setting up is purely to ensure the packs haven't been damaged in transit and to give us a base line to any future servicing of the pack.

Hi Fechter, Thanks for the link, I have sent them an email to see if they intend to build a higher spec module in the near future.

Thanks for all your responses guys, I do appreciate it and once we have our system set up, I will post a full spec images etc.

Ian
 
apheonix said:
Very suprised that nobody mentioned using a HP4328A Milliohmmeter to measure the internal impedance of batteries .
Without knowing this parameter , it is next to impossible to determine a safe charging or discharging of the cells
To give everyone a feel for number , the A123 cell have impedance in the order of 5 to 8 milliohms , the panasonic HH650D " D"
cells Nickel Metal Hudride rated at 6.5 A/H have impedance in the order of 2 milliohms ,have some that are down in the 1.8 region.
Can easily extract 300 Amps .sure they get hot ,(180Watts) but they are discharged in about 1 minute .
Impedance is a true measure of a cell quality the lower the better in all respect .
Click to expand...


I think the hp is a very accurate tool, but it is a bit expensive noh? 650$ on ...ebay..

Modern rc charger calculate and graph the internal resistor with good acuracy for less than 200$. at least mine do that: the megapower 960-SR.


one very important thing to check:

When measuring cells to match them, always ensure that have the same SOC and temperature!!! these two parameter can affect your measurement results for 75% of their value.. and only with few degree of variation!! :shock: That's what i experienced after doing many measurement on the same cell many times.

But when i did the same test again on these cells, with same soc and temperature the results was stable.


Doc
 
Jozzer said:
What a great product! Would be great on a Motorcycle, if only they doubled the current capability! ....

Steve
Click to expand...

It would definitely be possible to increase the current capacity by doubling or tripling the shunt. If they are using a hall current sensor, I remember reading in the application notes for those that you simply put another one in parallel, but don't use the output.

Doubling the shunt, for example, would cut all the readings in half, so you would either need to recalibrate the unit (not sure if this is possible), or correct the readings manually by multiplying by 2.
 
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