On 2 Aug 2014 at 14:47, Ben Goren via EV wrote: > _should_ I be worried about active cooling for > batteries? And, if so, what're good ways to go about it?
I'm pretty weak on lithium; the Li experts here should be able to give you specific heat resistance information. I'm more familiar with lead, and I can tell you that lead batteries suffer mightily in the heat. Again taking Solectria as an example, the early Forces (1992-1993) they delivered to APS (Arizona Public Service) had 12v flooded marine batteries by Johnson Controls. Their AC induction inverters had a modest 180 amp current limit, I think even 150a in the really early cars. So while they were running well above their design load of around 25a, they weren't stressed as much as they are in 400-600a DC EVs. In a temperate climates, those batteries typically gave 1-3 years of service, depending on use and maintenance. In Airzona, even with apparently decent care from APS mechanics, they were lucky to make it through even one summer. As another data point, it seems to me that GM's EV engineers decided to not even offer the NiMH EV-1 in AZ. In CA, they routed the aircon into the battery tunnel, which knocked down its Wh/mi numbers. (Battery ventilation on that car apparently wasn't too well designed.) > On Aug 2, 2014, at 1:18 PM, EVDL Administrator via EV <[email protected]> > wrote: > > > Solectria vehicles retained the factory Geo Metro aircon system, and drove > > the compressor with a small (1hp?) DC brushless motor and controller. The > > system seems to have been robust and reliable, if somewhat noisy. It used > > about 1500 watts from the traction battery. > > > That's an interesting thought. If I have the math right, that's all of 7 - 10 > amps at the 144 volts I'm planning on for the traction battery. That's exactly what the early Solectria Force aircon used - 7 to 10 amps at 144 volts. However, the Geo Metro aircon it was based on was a pretty efficient design to begin with. In those days, GM was battling Honda for top billing in the DOE fuel efficiency rankings (if you can imagine that), so they worked pretty hard at making the Metro an efficient car overall. That's part of the reason that an early Force can do 150-160 Wh/mi at the battery, though not with the aircon running. ;-) I have no idea whether you could find an aftermarket aircon as efficient as that, but starting with components salvaged from a high-mpg modern car might give you a leg up. David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ 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)
