Thanks Lee. I only knew about the wire ones.
On Mon, Jan 13, 2014 at 10:10 PM, Lee Hart <[email protected]> wrote: > Michael Ross wrote: > >> 120°F is high for PbSO4 isn't it? I always heard to keep the temp during >> charging below 100°F. >> > > Hot is good for performance; but bad for life. > > The EV racers deliberately heat up their batteries to maximize the power > they can get out of the. However, this shortens their life. But that > doesn't matter in racing. > > > I have been thinking about pipe tape for this...with a controller. You >> could weave a length of pipe tape among the cells, or fix it to a plate of >> aluminum. >> > > You need to know what you're getting. Some "tape" or "strip" heaters use > actual resistance wire (like nichrome, or just plain steel when they want > to be cheap). The resistance of a metallic wire is (roughly) constant; so > the current is predicted by Ohm's law. If you apply a fixed voltage, it > dissipates a fixed wattage, which produces a fixed temperature *rise*. The > exact amount of temperature rise is determines by the insulation and > thermal conductivity of the materials around it. You need a thermostat to > get a fixed temperature with this type of wire. > > Others types use a conductive rubberlike material, whose resistance > changes *drastically* with temperature, applied voltage, and other factors. > This type of wire is used to make it somewhat self-adjusting. They can make > its resistance increase with voltage, so it tends to self-regulate its > wattage. And, they can make its resistance go up as the temperature > increases, so roughly regulates temperature without a thermostat. > > The drawback of the latter type of heating element is that they aren't > very stable. Their characteristics drift over time. They are also easily > deformed by flexing or pressure (such as pinching them, bending around a > sharp corner, or piling heavy batteries on top of it). > > -- > Engineers like to solve problems. If there are no problems handily > available, they will create their own problems. -- Scott Adams > -- > Lee Hart -- See my Xmas projects at www.sunrise-ev.com/projects.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) > > -- 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/20140114/b4fb41c7/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)
