I have often wondered why Nissan (and others) used lead in the Leaf. Here are a few reasons I can think of:
Comparing to using a DC-DC converter directly: - lead allows for high current spikes, allowing a much smaller DC-DC. - having a separate battery allows the computers to function if something goes wrong with the main pack. - allows the main pack to be disconnected while charging and still have a separate power supply to keep the computers going (similar to above). Comparing to using lithium instead of lead: - again, from what I've read, lead beats lithium for max current. I believe all the above is solvable with lithium, but I suspect that Nissan and others found the lead solution more cost effective at the time. Peri -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bill Dube Sent: 26 December, 2013 7:49 AM To: Electric Vehicle Discussion List Subject: Re: [EVDL] EVLN: Why Do EVs have 12V PbSO4 Aux Batts When Li-ion Is Available? Lead _is_ toxic. They have systematically banned it from most uses (like paint and solder.) The writer makes an excellent point. They still use lead-acid 12 volt batteries mainly a matter of tradition and convenience and cost. If they invented them today, they could not go into production because of the environmental concerns. 50% of lead production comes from recycled sources, the rest is mined. Lead-acid batteries use 80% of that total lead production. The difference, 30%, ends up in the environment. Simple math. You just look at the lead association's own figures. The lead-acid battery industry claims 95% (up to 99%) material recycle rate, but they fail to mention that only counts the batteries that actually make it through the gates of the recycling facility. Great PR. Bad math. Bill D. On 12/26/2013 5:03 AM, brucedp5 wrote: > > % 'Lead-acid batteries = toxic' = writer's misinformation % > > http://www.plugincars.com/why-do-electric-cars-have-lead-acid-12-volt-batter ies-when-lithium-lighter-129118.html > Why Do Electric Cars Have Lead-Acid 12-Volt Batteries When Lithium Is > Lighter? > By David Herron . December 20, 2013 > > [image > http://www.plugincars.com/sites/default/files/P1129300%20copy.JPG > A 12 volt battery (lower right) under the Nissan Leaf hood. > ] > > Modern electric cars were made possible by lithium-ion batteries. But look > under the hood of any electric vehicle and you'll find a second battery, a > lead-acid battery, whose purpose is to power the 12-volt system. A reader > asked us why isn't this a lithium-ion battery as well? > > Lead-acid batteries have an obvious problem: their weight. Specifically, the > energy density, or kilowatt-hours of energy storage per kilogram of weight. > Using a lithium-ion battery instead of a lead acid battery for the 12 volt > system would reduce the car's weight, improving its overall efficiency. > > Another problem with lead acid batteries is toxicity. Some of us buy > electric cars because they're kinder on the environment, and lead acid > batteries are not exactly clean nor kind to the environment. Lead itself is > toxic, especially to young children, and there are several toxic chemicals > used in lead battery manufacturing. > > The 12-volt battery stores the power for the 12-volt system that runs > components like the lights, entertainment system and the heating/cooling > system. This battery is kept charged by a DC-DC converter which produces a > 12-volt source from the main battery pack. There's nothing magic about the > 12-volt system which makes lead-acid batteries technically better. Since > automakers obviously know how to design and build a high-voltage lithium ion > pack for the traction battery, they could obviously do so for the accessory > battery as well. > > Clearly it would be nice on at least two fronts to use something other than > lead-acid batteries for the 12-volt system. A quick glance at the price of > lithium ion versus lead-acid batteries though tells us why automakers use > 12-volt lead-acid batteries: cost. > > Unfortunately, we don't know the cost automakers pay for batteries. We can > estimate the cost difference between lithium ion and lead-acid 12-volt > batteries with the ALM-12V7, manufactured by A123 Systems. This is a a > plug-and-play replacement for for the industry standard 12-volt, 7 amp-hour > sealed lead-acid batteries that are used in a wide range of equipment. The > cost for the ALM-12V7 is $129 and its weight is only 1.875 lbs, while the > cost for 12-volt 7 amp-hour lead-acid batteries is in the $10-20 range, > weighing about 4.5 lbs. > > Lithium Pros is another maker of 12-volt lithium batteries, which are direct > replacements for typical car batteries and provide the kind of power output > required to turn a starter motor. The prices we found for their batteries > carry an even higher premium. The Lithium Pros 12-volt, 20 amp-hour battery > weighs only 9 lbs, but costs over $1000, which is much lighter than the > equivalent lead battery, but at a very high cost. > > Another gain is the engineering resources that would have to be spent to > design a suitable 12-volt lithium ion battery. All the automakers have > access to a ready supply of 12-volt lead-acid batteries from a long list of > manufacturers. It's a classic buy-versus-build decision, where it's cheaper > to buy a component than to design and manufacture it yourself. > [C plugincars.com] > > > > > For all EVLN posts use: > http://electric-vehicle-discussion-list.413529.n4.nabble.com/template/NamlSe rvlet.jtp?macro=search_page&node=413529&query=evln&sort=date > > Here are today's archive-only EV posts: > > EVLN: Cities can save big money by switching to EVs > EVLN: OpConnect keeps U.S. Navy EVs Charged > EVLN: Vending machine dispenses Chinese Kandi @$3.25hr r:75mi ts:50mph > EVLN: China Tesla website and dealership are up, and taking pre-orders > + > EVLN: EVs dominate the bus lanes into Oslo.no, more EVs than EVSE > > > {brucedp.150m.com} > > > > -- > View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/EVLN-Why-Do-EVs -have-12V-PbSO4-Aux-Batts-When-Li-ion-Is-Available-tp4666905.html > Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. > _______________________________________________ > 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) _______________________________________________ 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)
