/So does that mean you can't use Lithium below 0C / 32F ? That doesn't make any sense for those who live in the northern latitudes & Canada. I charge about .1C anyway (13 amps on CALB 130ah batts). I've charged at 20F but tonight it'll be 0F in VA. What about folks in Minnisota like Lee? I guess they use battery heaters but I thought most chemistries you could charge cold just take a bit longer due to higher internal resistance./
Yes, heaters. I used the Farnum heaters, taped to a sheet of aluminum with aluminum tape. The aluminum has the edges bent up about 1/2" and fits snuggly into the bottom of the battery boxes over 1/2" of polyurethane insulation, heaters on the bottom side of the aluminum, against the insulation. I bolted aluminum angle to the plate to help hold the cells in position, and strapped them down. There are a total of 10 heater pads in the boxes, connected in parallel and drawing a total of about 350W. They keep the cells at the set point temperature of 65F, even on successive nights of -5F lows. The insulation and cells' heat capacity are sufficient for the cells to remain above 50F if the car is left outside in 20's F temperatures for about 5 hours with the heaters off, so I only heat them when it is parked at home. Over 4 years of operation I have noticed almost no difference in performance of the car between winter and summer - main effect is more drive train stiffness/friction in winter. Prior to installing the heaters this way I had just laid them on the insulation and set the cells on top. The edges on the cell ribbing scrub the heaters and also slide around a bit if not strapped, which damaged one of the heaters after a couple years causing it to fail. The above installation works much better. -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Charging-Lithium-Below-Freezing-tp4667201p4667222.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. _______________________________________________ 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)
