Let me wade in here leading with my chin. (1) "Li batteries" come in a bewildering number of chemistries. Try this on for size: LiCoO2 (LCO), LiNiCoAlOx (NCA), LiMn2O4 (LMO), LiFePO4 (LFP), LiNiMnCoO2 (NMC), LiFeMnPO4, etc.
(2) Each chemistry has its own virtues and vices: voltage per cell, cycle life vs. DOD, operating temperature, specific energy (kWh/kg), specific power (e.g. 1C 35C), safety and thermal runaway. (3) Because of the high energy density, and high number of cycles down to 80% DOD (compared to NiCd, NiMHi and of course Pb), the early adopters were cordless drills laptops, cell phones and (yes) battery pack for commercial jets. All of these are mobile applications (keep this in mind for later). (4) There were a number of highly publicized reports of fires -- car, 787 Dreamliner, laptops and today hoverboards. The Li batteries in the 787 and the laptop fires were LiCO2. Let's forget about the hoverboard fires for now. LiCO2 has the lowest (max) operating temperature 150 deg-C. Apparently it was relatively easy to get the battery temperature up to that value, if there was inadequate forced air cooling or lack of sophisticated conduction cooling (including pumped liquid coolant) (5) And, I think we are all aware of this, some of the reports of fires caused by Li batteries were BOGUS sensationalized accounts. My (least) favorite account was the one where a pair vehicles parked in a carport/garage were destroyed by a fire. One of the vehicles was a hybrid, the other was a truck (converted to batteries and electric propulsion by a DIYer). The initial account blamed the hybrid for the fire. Later it was found out the cause of the fire was a branch circuit the same DIYer brought out the garage for his L2 charger. I believe he undersized his wire and oversized his breaker. (6) Now come the hoverboards. Many of them have been rushed to the consumer market without good engineering. In many products, it is difficult if not impossible to trace the manu for the batteries or the charging system. There have been reports of bogus UL stickers. Basically, STAY AWAY FROM HOVERBOARDS! (7) For stationary application -- off-grid, grid-tied battery back-up and grid-tied with load shifting applications -- energy density is not so critical, and safety IMHO is paramount. Guess what? LiFePO4 (and LiFeMnPO4 I believe) have much higher (max) operating temperatures, something on the order of 270 deg-C And about 2/3rd's the energy density of LiCO2 (105 kWh/kg vs. 170 kWh/kg). Guess where Pd-acid fits in here? ~40 kWh/kg. Actually, an AGM that I have had success with -- the SunXtender PVX2580 -- weighs in at 258 Ah (24 hour rate), 12 V nominal and 72 kg for 43 kWh/kg. Of course specific power (kW/kg) and self-discharge rates are also important and the LiFePO4 fairs very well by comparison with Pb-acid. (8) Cost? I think I paid something on the order of $500 for the PVX2580 (it's been a while) so that’s $6.20/Wh. Of course you could get a flooded cell Pb-acid battery for less -- you do the math. I have not yet purchased a comparable Li battery, but Elon Musk says his Powerwalls will sell for $2.30 to $2.90/Wh. We'll see. Despite Musk's slick presentation, the Powerwall is not generally available. I have heard numbers on the order of $5-7/Wh for other Li batteries. The problem I have encountered is that most of the vendors I have contacted are interested in selling an integrated system with battery management and an inverter. I am trying to reach Larry at Starlight Solar to get pricing on his 100 Ah nom 12 V lithium batteries, which I understand is LiFeMnPO4, which I hope has the same physical and electrical characteristics as LiFePO4. (9) Battery management. Li batteries, depending on the chemistry, have very precise charging and discharging requirements and esp the LiCoO2 batteries. I hope I'm not making undue assumptions, but the LiFe(Mn)PO4 is much more robust and may be compatible with programmable Pb-acid charge controllers (with appropriate adjustments). (10) Based on the application I am currently work on -- stationary, indoor, grid-tied, daily charge/discharge cycles for load management -- the LiFePO4 has superior electrical and mechanical characteristics, and the life-cycle cost is MUCH LESS than even AGM batteries. It's a new world out there. Tech support, reliability, warranties, will all get sorted out in time. Hopefully our early adopters will be handsomely rewarded for their efforts. As I said, my application is a not quite mainstream (yet), and I will probably end up buying an integrated system. Peter T. Parrish, Ph.D. President, SolarGnosis 1107 Fair Oaks Ave. Suite 351 South Pasadena, CA 91030 (323) 839-6108 [email protected] -----Original Message----- From: RE-wrenches [mailto:[email protected]] On Behalf Of [email protected] Sent: Monday, January 25, 2016 12:28 PM To: RE-wrenches Subject: Re: [RE-wrenches] LiFePO4; WAS Availability of Powerwall Batteries Dan, Can you give us a quick over view of the ins and outs of the NiFe batteries? Thanks, Mark Frye > Marco; > Winter storms, hurricanes, earthquakes, tornados, floods, etc. - > backup power. Maybe load shaving as the utilities get more persnickety > on time of use upcharges. > > Of course for most folks, an infernal combustion generator is far more > cost effective than batteries. But for an extended grid outage and > with a critical loads subpanel installed, PV charges on sunny days, > generators still need fuel which may be in short supply or > inaccessible. > So, preppers. Most are surprised at how little autonomy time they get > from a really expensive battery bank, but if it's TEOTWAWKI at least > their solar "fuel" is free, minus the amortized cost of the battery > bank. I get lots of phone calls from preppers who really need lithium > prescribed by their psychologist far more than they need it in a > backup battery bank...... > > Lithium batteries seem impressive on how long they can sit unused / > float with no degradation, but I'd rather let all y'all be the guinea > pigs on them for awhile. I'm doing my part by guinea pigging NiFe > batteries off the grid. So far, so good, and darned glad I now know > their ins and outs compared to lead acid. I would have been horribly > embarrassed if I'd done my first NiFe battery bank for a customer > instead of for myself....I chose NiFe here simply because of decades > of historical data, I don't trust Lithium yet for longevity, but > thanks Larry C and others on this list who have been doing lithium > batteries for years and reporting their results here. > > This Wrenches List is the gold standard of good information! > > > Dan Fink > Adjunct Professor, Ecotech Institute > IREC Certified Instructorâ„¢ for: > ~ PV Installation Professional > ~ Small Wind Installer > Executive Director, Buckville Energy > NABCEP Accredited Continuing Education Providersâ„¢ > 970.672.4342 > > > > On Sat, Jan 23, 2016 at 1:28 PM, Marco Mangelsdorf > <[email protected]> > wrote: > >> Aloha Larry, >> >> >> >> To take a step back…what’s the compelling value proposition from >> the homeowner’s perspective to incur this non-trivial additional expense? >> To >> be blunt, what’s in it for them? Back-up power? First adopter mojo? >> >> >> >> Thanks, >> >> marco >> >> >> >> >> > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/[email protected]/maillist > .html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > _______________________________________________ List sponsored by Redwood Alliance List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/[email protected]/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org _______________________________________________ List sponsored by Redwood Alliance List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/[email protected]/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
