I have been looking at this, seemed to me that for the capacity, smaller batteries can discharge a higher current, I guess that's why Tesla uses 7000 small cells? R/C batteries are often rated at 90C or even greater, I have seen 300C. Look at this: http://www.hobbyking.com/hobbyking/store/__51838__Turnigy_nano_tech_Ultimate _6000mah_2S2P_90C_Hardcase_Lipo_Pack.html 6 Ah and 90C gives 540 Amps! From a 2 Cell battery you can wrap your hand around.....
-----Original Message----- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of EVDL Administrator via EV Sent: Tuesday, 22 July 2014 8:21 p.m. To: Electric Vehicle Discussion List Subject: Re: [EVDL] How crazy am I? Another factor to consider is that while power capability varies by design, as a general rule, smaller cells are usually capable of lower power output. For example, the CALB 40ah cells I mentioned are rated for a maximum discharge of 2C (80 amps). At 144v, 80a is 11.5kW. Allowing for losses, that's only about 12hp from your motor! Not being a lithium expert, I don't know how much more than this you can actually draw before voltage sag really kicks in. But I'm pretty sure that pushing them too hard will shorten their lives significantly. If you expect sporty, Mustang-y EV performance, but don't want to carry around much of a battery, you'll need to find some cells designed for high power. The 90ah Winstons I mentioned are rated for only 1C continuous, but they say you can draw 10C for 10 seconds. It looks like you then need to allow at least 50 seconds of either zero or much lower current for the cell to recover (how often you can do this isn't clear from the spec). Other folks here may know how realistic this is, and/or have some recommendations for high power lithium cells. 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) _______________________________________________ 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)
