Hmm, Phil’s comment about battery drain is very interesting. Up until last year, My daughter had an older Lexus SUV hybrid . She worked in San Francisco and walked to work, so the car stayed parked for weeks sometimes. When parked for a week, the battery pack and the lead acid battery always went dead from some mysterious , undetectable current draw. Neither the dealer or Lexus ever traced ( or admitted a design flaw) in the supposed stray current, when parked. We never figured it out. Finally talked her into selling the d#%n thing. Wondering if something to do with cell monitoring was killing the batteries.
It’s gone out of our life, ( dad’s are the 24 hr on call emergency fixit guys), but still curious. Thanks , Glenn Sent from my iPhone > On Apr 20, 2021, at 9:29 PM, (-Phil-) via EV <ev@lists.evdl.org> wrote: > > The problem most people are seeing is the high quiescent drain. IMO, this > started with the Prius with the smart-key option. It was exacerbated with > the introduction of telematics, which means there's a cell modem always on > in your car now. Most modern cars now have both. So if you drive every > day, and long enough to get your absorption phase completed, likely not > going to be much of a problem, but if your car isn't used as often, you are > in trouble. > > Ultracaps (or any capacitors) have a linear Dv/dt plot, which means voltage > falls immediately on discharge. This means to get the capacity anywhere > CLOSE to what you get with lead-acid, you'd need a ludicrously large cap > array. > >> On Tue, Apr 20, 2021 at 8:36 PM George Tyler via EV <ev@lists.evdl.org> >> wrote: >> >> The leaf battery behaves much like the 12V Prius battery in my experience. >> They both seem to fail earlier than they should, but when should they fail? >> That is "opinion". The failure mode is different, probably because they >> don't fail by not turning a started motor? So you don't know capacity is >> almost zero. >> I don't think a lithium is good for this application. To get >> voltages that are close enough you have to use LiPo4 litiums, with a very >> flat discharge curve. This means that the charging voltage is not optimal, >> although they do work in this application in ice cars with 14.7V charging. >> 4 >> cells at 13V is 3.25/cell, that's totally flat for these batteries! 14.7V >> in >> an ICE is 3.675V per cell which is about right. Temperature compensation >> for >> a lead acid may be way off. How about a supercap "battery", much less >> critical. Seeing that we don't notice the leaf battery losing capacity >> until >> it's dead, maybe we don't actually need much capacity? >> GWT >> >> -----Original Message----- >> From: EV On Behalf Of Lee Hart via EV >> Sent: Wednesday, 21 April 2021 2:14 pm >> To: Lawrence Rhodes via EV <ev@lists.evdl.org> >> Cc: Lee Hart <leeah...@earthlink.net> >> Subject: Re: [EVDL] From my nissan leaf .com: Why the Leaf 12v system >> undercharges the 12v battery. >> >> Lawrence Rhodes via EV wrote: >>> https://mynissanleaf.com/viewtopic.php?t=22752 According to these guys >>> a lead battery is not what a Leaf needs. Seems a lithium of some sort >>> would do great. Another site said the DC/DC converter can put out as >>> much as 120amps. The brakes and other systems that run on the 12v >>> system might need a boost if the battery fails and braking is very >>> important. After finding out that the lead battery is under charged I >>> suspect an undercharged lithium battery might fair much better and for >>> longer. Lawrence Rhodes >> >> I don't "buy" it, Lawrence. Too many of his comments are just opinions; not >> facts. Just a few glaring points: >> >> - A 12v battery *will* reach full charge at 13.0v; it just takes a long >> time >> (like a week or so). >> - He ignores temperature compensation. The Leaf does temperature compensate >> its charging. >> - He ignores aging. The older the battery, the lower its basic charging >> voltage. >> - 14.4v will easily fully charge a 12v battery. Remember, if it's holding >> the battery at around 13.0v, it's already close to full; so it takes very >> little time at 14.4v to finish the job. >> >> Lee >> >> _______________________________________________ >> Address messages to ev@lists.evdl.org >> No other addresses in TO and CC fields >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >> ARCHIVE: http://www.evdl.org/archive/ >> LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org >> > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20210420/bc2bc0ee/attachment.html> > _______________________________________________ > Address messages to ev@lists.evdl.org > No other addresses in TO and CC fields > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > ARCHIVE: http://www.evdl.org/archive/ > LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org _______________________________________________ Address messages to ev@lists.evdl.org No other addresses in TO and CC fields UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/ LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
