Subject: Re: [EVDL] Tesla...lost how much charge overnight? 25%??? 60 miles?? >Probably none of (a) to (e)... and most likely it isn't really that high a >drain, it's just that range........ I'm not even talking about the range computation here. I'm talking about the SOC data. That's where I got the 500 watts.
I didn't realize they would use the battery to warm itself. That seems rather foolish to do when the car is nearly discharged. A warm battery but nowhere to go. But if thermal is important, (which I'm not sure it is), if you did, it would make a lot of sense to make sure the batteries were very well insulated. A 500 kg battery pack has a lot of thermal mass and if properly insulated it could stay warm for 24 hours with no energy at all. 500 kg at 1000 J/deg C has about 500,000 joules per deg C 1 square meter of insulation at R1 (metric units) would let 3600 joules/hour/deg C. If you had 6 sq meters of area and 1 inch of foam (about R1 metric units) and a 10 deg C difference, that would be 216,000 J/hour or about 1/2 deg C/hour natural cooling. And if you wanted to heat it to keep it steady state, 216,000 J/hour is only 60 watts. I've never bothered with heating my batteries, and so far they've worked pretty well when it's cold. As another thermal aside, most electric cars seem to have a resistance heater inside the cabin, but some sort of active cooling for the motor. Now doesn't that sound kind of foolish too? Why not at least provide an option to duct the heat off the motor into the cabin like an ICE. I'm guessing there is 1-2kw of waste heat coming off the motor that could be used in cold weather. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20130218/ef818a20/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)
