Hi Roger,

Thanks for the thoughtful reply.

I think I need to be a notch or two above garage testing.  To provide
results worth referencing.  I do have to be frugal and not spend where good
things can be fabricated.  We want to be cost effective for clients that
aren't at the million$ a year in sales level.  Large OEMs can care for
themselves.

Since we are a functioning test lab, I have an assortment of quality
measuring instruments - just not specific to battery testing.  We test
solar thermal collectors.  Lots of radiation, temperature, and flow
capability.

I have a pretty comprehensive data acquisition system, National Instruments
cRIO controller, 32, 5V biderectional DIO channels, 8 channels of high
speed 5V bidirectional DIO, 16 channels of 24V DO, 8 channels of analog
 input.  I have a couple 6 1/2 digit DMMs and 3  20 channel cards to use in
them (slow but accurate).  All that can be programmed with some
sophistication using LabVIEW.  I won't need PLCs.

With some relays and contactors, I can probably move on to the power
supplies and possibly load banks for a place to spend money.

For cell testing I have an EMS 7.5V 300A 1700W supply.  I have not really
used it, so I don't know exactly how to control it automatically.  It could
do cell modules, but not packs.

Then I have a couple of transformers in Lestronic II PbSO4 chargers 24V
25Amp, and 36V 30A.  And I have a 480V:120V 7.5KVA transformer that ought
to be useful somehow.

It is a start.

If I can get any funding at all, I think knowing the power and load needed
for the most probable testing, and getting good equipment to provide those
would be smart.  I think I also want some reference standards.  But, I
might make them, or settle for the calibrated DMMs.

Mike

On Thu, Nov 6, 2014 at 7:48 PM, Roger Stockton via EV <ev@lists.evdl.org>
wrote:

> Michael Ross wrote:
>
> > I am investigating how to test cells and packs - I will need to charge
> and
> > discharge.
> >
> > If I have a programmable electronic load, rather than purely resistive
> > loads, is this an unrealistic way to discharge batteries?
>
> Thought I'd mention that while a programmable load is an *excellent* way
> to discharge when testing batteries, it can be pricey (typically about $2/W
> on the used market).  If you have a load bank, or need one for other
> reasons, then by all means use it.  If you are considering buying one just
> for this purpose, then carefully consider what other equipment you have or
> will need to acquire to go with it.
>
> If you get a load large enough to handle your needs on its own (i.e. it
> can handle the desired discharge current even with a fully-charge battery),
> and you get one equipped with a communications interface (GPIB/IEEE-488 or
> RS232, typically), then you may be able to use its own voltage and current
> measurement capabilities to avoid the need to purchase a standalone data
> logger or USB DAC/digital I/O device to take measurements and control
> things.
>
> If you already have a data logger or other means of measuring/controlling
> a load and charger, then perhaps consider using a passive load in parallel
> with a smaller electronic load, so that you can save money on the
> electronic load purchase.
>
> Or, you may be able to go in entirely the opposite direction and use a
> completely passive load bank.  I started out with a battery cycler setup
> consisting of a bank of 12VDC Edison-base (household screw-type) light
> bulbs switched by a continuous duty Ford starter solenoid-type RV battery
> switch.  A simple QBasic program on an old laptop controlled the relay for
> the load and another for the charger via the parallel port.  An E-meter
> with the RS232 comms option provided voltage, current, etc. measurements to
> the QBasic program.
>
> Incandescent bulbs have the nice property that the current they draw
> varies less with voltage than would a purely resistive load, so you can get
> a reasonably constant discharge current simply.  Unless your battery
> voltage is significantly below the rated voltage of the bulbs, they also
> provide a nice visual indication that they are on and hot. ;^>
>
> Cheers,
>
> Roger.
>
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-- 
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happiness, or should I help others gain happiness?
*Dalai Lama *

Tell me what it is you plan to do
With your one wild and precious life?
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<http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html>

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Michael E. Ross
(919) 550-2430 Land
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<michael.e.r...@gmail.com>
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