It is simply to protect the battery that charging throttles back somewhere around the 80% mark from fast-charging to lower speed. That is why Bruce has recommended that a Fast (level 3) charger always be accompanied by a level 2, so that someone who needs to top up to above 80% can first do a fast charge to 80% and then free up the fast charger for the next fast-charging vehicle, while being topped up at the lower speed of the level 2, since the charging speed above 80% is not dependent on what the charger can deliver as much as on what the battery can take without damage. What typically happens is that around that 80% point, the voltage of the cells will rise enough that the charging algorithm transitions from being current limited (how much can the charger deliver to the battery) to voltage limited (what max voltage is allowable for the cell) and the current will correspondingly fall off over time while the cell is going from 80-ish to 100%, so it is an area of diminished returns: you got to wait longer for every next percent added above 80% charge, so that is why it only makes sense to fast-charge to 80%.
Hope this clarifies, Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.com Skype: cor_van_de_water XoIP: +31877841130 Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 -----Original Message----- From: [email protected] on behalf of Martin Winlow Sent: Sat 4/5/2014 3:33 PM To: Robert Gienger; Electric Vehicle Discussion List Subject: Re: [EVDL] CHAdeMO DC Charge time? Hi Bob, I can only offer you the dubious benefit of my UK experience using a chademo on my i-Miev... At zero charge state on the car the chademo says it is supplying ~120A @ 330V. The charge power does gradually reduce until at 80% full, the currant has fallen to about 20A @ 330V and automatically the charging stops. If you re-start the chademo, it will continue up to 100% but I don't know if the currant stays at 20A or what (forgot to look!). MW > On 5 Apr 2014, at 23:21, Robert Gienger <[email protected]> wrote: > > Occasionally I charge at Premiere Nissan in San Jose, CA. When using the > CHAdeMO DC fast charger, I noticed it charges very fast up to 80% and > then slows down to a trickle. Am I correct or is this just my imagination? Is > it faster to top off with a 220v level 2 unit? > Thanks, Bob Gienger _______________________________________________ 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) -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/ms-tnef Size: 4123 bytes Desc: not available URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140405/05ab519a/attachment.bin> _______________________________________________ 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)
