Excellent, Roger, Thank you. On Thu, Nov 6, 2014 at 7:08 PM, Roger Stockton via EV <[email protected]> wrote:
> Michael Ross wrote: > > > 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. > > Probably not, unless the electronic load you choose is designed to be used > with an external load bank, or you plan to control the electronic load from > a remote source rather than simply setting it to regulate the desired load > current on its own. > > An external load bank (coat hanger or other wire in a bucket of water or > fan-cooled power resistors, etc.) can be useful if you want to increase the > power capability of your electronic load (or conversely, to be able to use > a smaller - and cheaper - electronic load than you could otherwise). > > For instance, when testing a 12V battery you will typically discharge to > about 10V minimum; if your desired discharge rate is 75A, then your minimum > load is about 750W. If you want to be sure that you can pull the full 75A > from a freshly charged battery, it needs to be able to handle the maximum > load of about 15V x 75A = 1125W. If you use a resistive load to handle > most of the minimum load requirement, then your electronic load only needs > to be sized to handle the difference (in this case 1125-750 = 375W) instead > of the full amount. > > > Someone mentioned needing a heat dispensing means would be needed with a > > programmable load. > > Not unless you pick up a water-cooled load. The air-cooled loads have > built in fans and will cool themselves. If you are discharging a large > capacity battery in a small room, you may need to open a window or > otherwise allow for some ventilation as the room will warm up. > > > Any recommendation of actual units to look at? > > I've mostly used DLP- and RBL-series units from TDI (Transistor Devices). > They are often available used, and are generally basic rugged units. You > don't need particularly fancy features for battery discharging as most > often you will use the load in constant current or possibly constant > power. In constant current mode, the TDI loads can have the load current > controlled remotely by a 0-5V signal, so you can use an external means to > monitor the total load current drawn by the electronic load and a resistive > load and then control the electronic load to regulate the total current at > the desired level. They also can be enabled/disabled remotely with a > simple relay or opto so that your data logger can turn the load off when > the battery voltage reaches the desired end-of-discharge voltage. Some > models support IEEE-488 (GPIB) communication, in which case you can achieve > all of this controllability through software control, provided you spring > for a GPIB interface for your PC. > > I've also used loads from NH Research (NHR, this is what I have at home) > and Chroma. > > This site provides an idea of what sort of devices are available on the > used market: > > <http://www.alltest.net/s.nl/sc.2/category.16/.f> > > 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) > > -- 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] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20141106/e13baa32/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)
