The same things hold as for lead-acid: There is some thermal mass in the pack, so that if the average between day and night is above freezing then you may be OK anyway. If avg temp drops below freezing for long time then it might be wise to park and charge in a warmer location (even an attached unheated garage stays well above outside nighttemps). For surviving constant freezing temps, a way of insulating and pre-heating the pack is needed. The circuit is relatively simple: measure temp of the pack when plugging in and start heating it, once the temp is above freezing the charger can start and likely the heating can stop if the charger is dumping its waste heat into the pack, also allowing it to vent out any gases and avoiding it to cook to death in summer, venting helps both ways.
Hope this helps, Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Michael Ross Sent: Monday, January 06, 2014 1:18 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] Charging Lithium Below Freezing Mark, I think it means you need to charge them in a warm place and/or back off on the charge rate. Right now all I am hearing is that there is a spec on some cells. I am not clear on the why and wherefores of it all. I prefer not to fully accept manufacturer specs (particularly from China regarding Li batteries, because the testing specs are mostly unknown). They could be offering a CYA spec, or they could just be wrong. I have been trying to find out if purveyors of batteries even know what testing is done and the quality of it. Nada. Interesting conversations though. On Mon, Jan 6, 2014 at 4:02 PM, Mark Hanson <[email protected]>wrote: > Message: 13 > Date: Mon, 6 Jan 2014 11:13:52 -0800 > From: David Murphy <[email protected]> > 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.Best > Regards,Mark > To: Electric Vehicle Discussion List <[email protected]> > Subject: Re: [EVDL] Charging Lithium below freezing, should I drive my > gas car? > Message-ID: > <cahtzjazxhv3i2+ugau3ms_tyrnddvywyf2-dwjkt846nd7c...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > So the cells I am talking about are referred to as Lithium Ion Polymer, not > sure if that is the same chemistry... > The specs for these type of cells define three temperature ranges for > charging. (cell temp, of course, not ambient) > from 0C to 10C > 0.1C max Constant Current (CC) to 4.2V, 4.2C Constant Voltage (CV) to > 0.05Cmin cut-off > 10C to 23C > 0.5 max CC to 4.0V, 0.2C CC to 4.2V, 4.2V CV to 0.05C > 23C to 45C > 0.5C CC to 4.2V, 4.2V CV to 0.05C > > for discharge, the oeprating temp is -20C to 60C > > Hope that's helpful... > > david > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140106/bfe08 bc2/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) > > -- 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/20140106/401f a7e0/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) _______________________________________________ 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)
