No, a programmable load will typically have built-in load, but there may
be units that only are a controller

and expect a bank of resistors or the like externally.

For doing it on the cheap, you can take a length of wire that can
dissipate the heat, either by spreading it out

(I once did several cycles of testing on a 12V 110Ah battery using about
200 ft of copper wire strung around

my garage on two parallel strings, so I got about 80A of discharge
current).

You can also build a dissipative load relatively easy with power MOSFETs
on a heatsink, a shunt resistor

to measure the current, an opamp to compare the desired current to the
set value and drive the MOSFETs

and a small 12V power supply to power the thing.

Add a second opamp to measure voltage and stop the discharge at a set
voltage and you are pretty far

along in having your own programmable load. Add a meter or two and some
indicators and you are in business.

 

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
<http://www.proxim.com> 
Email: cwa...@proxim.com Private: http://www.cvandewater.info
<http://www.cvandewater.infom> 
Skype: cor_van_de_water Tel: +1 408 383 7626

________________________________

From: Michael Ross [mailto:michael.e.r...@gmail.com] 
Sent: Thursday, November 06, 2014 2:25 PM
To: Cor van de Water; Electric Vehicle Discussion List
Subject: Re: [EVDL] Q about using an electronic load.

 

I have heard of putting a roll of fencing in a tank to steam off heat.
Is this useful with a programmable load?  Or is this just a crude way to
discharge.  

 

Someone mentioned needing a heat dispensing means would be needed with a
programmable load.  

 

Any recommendation of actual units to look at?

 

On Thu, Nov 6, 2014 at 4:55 PM, Cor van de Water via EV
<ev@lists.evdl.org> wrote:

Correct - a *supply* can use switching to minimize losses,
a *load* simply burns the power away in linear mode (current control).

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: cwa...@proxim.com Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626
<tel:%2B1%20408%20383%207626> 



-----Original Message-----
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Roger Stockton
via EV
Sent: Thursday, November 06, 2014 1:12 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Q about using an electronic load.

Michael Ross wrote:

> If I have a programmable electronic load, rather than purely resistive
> loads, is this an unrealistic way to discharge batteries?
>
> I gather they use power MOSFETS and switch them to product the desired
> output current from the batteries.  I think this implies some
transients
> at some frequency.

A programmable load is fine for discharging batteries.

I believe the power devices are operated in linear mode, not PWMed, and
have not observed any transients on the load current on any of the
electronic loads I've used.

Cheers,

Roger.

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-- 

Put this question to yourself: should I use everyone else to attain
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?

Mary Oliver, "The summer day."

 

To invent, you need a good imagination and a pile of junk.

Thomas A. Edison
<http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> 

 

A public-opinion poll is no substitute for thought.

Warren Buffet

 

Michael E. Ross

(919) 550-2430 Land

(919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones>  Google
Phone

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