I would like to make some comments in response to both Al Lococo's and Andrew Roddy's respective posts below.
First, let me just point out that large-format (85-100Ah) NiMH batteries have a well-established and proven calendar life of over 10 years and 200,000 miles in EVs. Al wrote: > Lithium Ion batteries have excellent power to weight and size ratios for > electic vehicles. Al, I'm not sure if you meant "power" or "energy". If you meant "power", it depends on what lithium batteries you are talking about. The power density of the 18650 LiCoO2 laptop cells used in the Tesla and the eBox is not all that great. A123 and Kokam, for instance, have much higher power density than those used in the eBox and Tesla. I'm going to assume that maybe you meant "energy", or at least that's what I'll discuss and how I'll frame the comparison here. The energy-to-weight and energy-to-size ratios, which I will refer to as gravimetric energy density and volumetric energy density, respectively, are indeed much greater for the 18650 LiCoO2 laptop *cells* used in the Tesla and eBox versus large-format NiMH, but that is *only* at the *cell* level and does not hold true at the pack level. At the *cell* level, the 18650 LiCoO2 laptop cells are about twice as energy dense, gravimetrically, as NiMH, at around 120 Wh/kg for the 18650 LiCoO2 cells vs. 60 Wh/kg for NiMH. (ACP and Tesla had actually previously used even higher energy density LiCoO2 18650 cells, up to 140-160 Wh/kg, but were forced to downsize to safer, lower capacity cells, with thicker separtors, etc., due to significant concerns about the serious thermal runaway/combustability safety hazard with those batteries.) But again, this is all at the cell level that we are talking about with those 18650 LiCoO2 laptop cells. Andrew correctly referred to ACP's (same as Tesla's by the way) substantial safety measures in their sophisticated, triply-redundant BMS, at the individual *cell* level, water-cooled thermal management system (TMS), etc. One thing Andrew didn't mention is that each of those individual 5,088 cells in the eBox and 6,831 cells in the Tesla is encased in its own thick, heavy steel sarcophagus, in order to contain and isolate any thermal runaway and fire/explosion in that cell and prevent a chain-reaction spreading to other cells and the rest of the pack. Well, what do you think all those thick, heavy steel casings around each individual cell, plus all of that complex, sophisticated electronic circuitry for each individual cell, plus all of those liquid cooling jackets and piping, do to the erstwhile gravimetric and volumetric energy density advantage of 18650 LiCoO2 laptop cells, at the *cell* level, over NiMH, when you balloon all of that up to the pack level, with all of that excess volume and weight for all of that required BOS safety gear? ... Hhhhmmm, yeah, you guessed it, you lose most of that energy density advantage of lithium over NiMH and bring the two much closer together. The advantage of NiMH is that it is so robust that it doesn't even need a battery *management* system in the sense that we normally think of that term for lithium batteries, i.e. individual cell protection circuits, voltage clampers, etc. None of that is necessary nor used for NiMH battery packs in EVs like the RAV4-EV and Vectrix. In fact there is absolutely no electronic circuitry at all at the cell level. There is only a battery *monitoring* system (as opposed to a battery *management* system) at the *module* level. Basically all this consists of is a simple temperature probe and voltage monitor on each module with communications signaling back to the controller and charger, telling the charger when to shut off, etc. Very basic and simple, costing only a few hundred dollars per vehicle, as opposed to over $10,000 in many cases for a lithium battery pack BMS and TMS. NiMH can take and absorb a huge amount of overcharge, much more so than sealed lead-acid, for instance, more like similar to flooded lead-acid. In fact, NiMH is very similar to flooded lead-acid in the way that an equalization charge is run about once a month -- at 3A for around 2 hours. If you don't allow the equalization charge to run when the charge controller calls for it once a month and let it go, say, 6 months without equalizing, then when the equalization charge eventually runs, it will do so for about 6 hours. ... Yeah, 6 hours of putting overcharge into those NiMH batteries. No problem. Andrew wrote: > I believe the replacement cost for the eBox battery pack today would be > approximately $25,000, over time the price should go down. Quite to contrary, the price of these LiCoO2 battery packs in the eBox and Tesla are going *up*, not down, while the price of NiMH battery packs has been falling. In the last year, the price of nickel has fallen from $54,000/ton to $30,000/ton today, whereas the price of cobalt has gone in the opposite direction, doubling in price from $26/lb. to now over $52/lb. This fact, as well as other problems with Tesla's battery pack, is the real reason for Tesla's continuing delays (with the transmission problem excuse being largely a smoke-screen). The cost of Tesla's battery pack has increased so much that they are now underwater on the $100,000 sales price of the Signature-100 cars that they have pre-sold and must now absorb a loss on those first 100 cars due to the rising cost of the battery pack. On the calendar life issue of lithium batteries, it is a well established fact that it is no more than 3 or 4 years. Under various NDAs, I have seen a number of confidential internal company calendar life studies of lithium battery manufacturers which document this scientifically. Every single battery manufacturer CEO I've spoken with, and I've spoken with a number of them, admits this privately. Some have even admitted this publicly, on the record. The well established empirical record of on-road field experience with lithium-powered EVs, of both hobbyists and the big automakers, going back over a decade now, shows that these battery packs lose 10-20% of their capacity per year in a hot climate like Florida and 5-10% of their capacity per year in a cold, northern climate. This corresponds to the scientific lab studies of accelerated calendar testing that all the lithium battery manufacturers have done but most don't like to talk about publicly and some won't even admit to doing. Tesla's senior executives have admitted to at least some of their customers (from my communications with them) that they expect the battery pack's calendar life to be about 4 years and definitely need replacing by 4 or 5 years. I give Tesla a lot of credit for their honesty, integrity, and business ethics. Lithium battery manufacturers have all been aware of the serious calendar life problem for well over 10 years now and have been intensely working on trying to solve this problem for over 10 years, but little progress has been made to date. Despite that, I nevertheless remain hopeful that some very slow, gradual progress is starting to be made in this area and that within 5 years we should have some pretty good lithium batteries that should hopefully last 10 years in an EV. I would agree that we need both NiMH and lithium batteries. The more the better. It is people like Andrew Roddy and Cliff Rassweiler who are stepping up to the plate to be pioneering early adopters of lithium battery technology that is making this continuing progress possible, which will benefit all of us being able to get much better, longer-lived lithium battery packs in EVs in the future. Without people like Andrew and Cliff paving the way and helping to pay the development costs, none of this would happen. We owe them both a debt of gratitude. Best regards, Charles Whalen Delray Beach, FL From: "Al Lococo" <[EMAIL PROTECTED]> Subject: Re: [FLEAA] NiMh PATENT Re: listserv Digest, Vol 8, Issue 3 To: "FLEAA Mailing List" <[email protected]> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original > Fran, > You have written a great summary below. I have also read Charles' > contribution on the subject. He certainly has a long and deep perspective > on the issue. > > I think your summary and his perspective will give us all a good idea of > FLEAA opinion on this matter. > > I would like to add to your summary, and comment respectfully, on a few > points Charles has mentioned. > > Lithium Ion batteries have excellent power to weight and size ratios for > electic vehicles. On the other hand, they have a high cost and a calendar > life of three years. The callendar life adds to the cost over the life of > the car. Still, they are an excellent choice where cost is not an issue > and > where performance and weight are an issue, as in a sports car like the > Tesla. I wonder if Andrew can tell us what portion of the E-Box > conversion > cost is for batteries. > > NiMH batteries are tried and proven. Charles has explained this to me, > and > others, in great detail at meetings. They are heavier and larger than > Lithium Ion. On the other hand, their longer life cycle and initial cost > are more approiate for and SUV or Pickup Truck where there is more space > and > greate weight carring capacity. > > The point being, we need both technologies. > > I was never proposing that the FLEAA or EAA try to bring a suit against > Cheveron, Texaco or Cobasys. I agree with Charles, this would be futile. > On the other hand, a little media exposure on this issue might not hurt. > I > am receptive to persuasion on this point. I have taken steps as an > individual to get media attention on this issue. I would love to be able > to > say the FLEAA or the EAA support this view. > > One other point Charles mentions is limited market. Here again, I may > need > to be enlightened. My view is that a holder a patent, wants to profit > from > this asset. To do that he needs a market and a product. Certainly the > electric vehicle market is limited. We have a chicken and egg problem. > No > batteries, no cars. No cars, no batteries. But, what about all those > gasoline cars? Are they a potential market for this technology? Perhaps > not. Every car and truck does have a 12V accessory battery. There are > also > a large spectum of vehicles such as golf carts, fork lifts etc. using lead > batteries with a 3 to 5 year life. > > Well as I mentioned I do this for completeness. This may be a dead issue. > I am intersted in any help, anyone can give me, in my private pursuit of > this issue with the media. > > Cheers, > Al Lococo Date: Sun, 9 Mar 2008 12:39:52 -0400 From: "Andrew" <[EMAIL PROTECTED]> Subject: [FLEAA] eBox Batteries To: "'Al Lococo'" <[EMAIL PROTECTED]>, "'FLEAA Mailing List'" <[email protected]> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset="us-ascii" > Hi Al, > > I believe the replacement cost for the eBox battery pack today would be > approximately $25,000, over time the price should go down. > > The battery pack consists of 5,088 "18650" commodity lithium ion > batteries. > > I believe the calendar life of the battery pack is greater than 3 years; > it > should be at least 5 years with AC Propulsion's advanced battery > management > and thermal management system. > > Andrew _______________________________________________ Florida EAA mailing list [email protected] http://www.floridaeaa.org
