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: [email protected] Private: http://www.cvandewater.info <http://www.cvandewater.infom> Skype: cor_van_de_water Tel: +1 408 383 7626 ________________________________ From: Michael Ross [mailto:[email protected]] 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 <[email protected]> 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: [email protected] 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:[email protected]] 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. _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) -- 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 (919) 631-1451 Cell (919) 513-0418 Desk [email protected] <mailto:[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20141106/3aca5f24/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
