Thank you Cor.  I am cash strapped so this sort of DIY advice is very
helpful.

Mike

On Thu, Nov 6, 2014 at 5:33 PM, Cor van de Water via EV <ev@lists.evdl.org>
wrote:

> 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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>
>
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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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<michael.e.r...@gmail.com>
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