[EVDL] Is your EV doing enough?
Is your EV doing enough? Today I randomly found the last available parking spot at work at a Tbone intersection, where, I realized that every driver on campus has to see it square in their eyes as they made the turn to go home. Why have I not been doing this for the last 4 years?! My car is emblazoned as an EV with big 8 tall decals because I am a proselytizer for EV's but realized I have been missing an excellent opportunity for outreach EVERY day ALL day, by simply how I choose to park every morning. Instead of trying to eek out the last 100 yards from my walk to the office door, heck, it's only a tiny effort with great rewards to optimize for VISIBILITY instead of laziness. Besides, the extra 100 yards I should be doing anyway. Remember 99% of everyone around you has no,t and will not ever see an EV as an EV until they either wreck into one, or find one parked behind them when they ICE a charging spot. So it is up to us to capitalize on our investement in the future and be OBVIOUS. Bob Bruninga, WB4APR http://aprs.org/EV-charging-everywhere.html ___ 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)
Re: [EVDL] Phys.org: Could hemp nanosheets topple graphene for making the ideal supercapacitor?
Ultracaps and drag racing comes up quite frequently. It's been tried and it's not a good match. Dragsters need more power the the further down the track they go. Ultracaps ability to deliver power drops the more you discharge them due to their voltage dropping. (E = 0.5CV^2) Essentially you run out of ooomph by the time you get to the end of the track where you need it the most. So to compensate you have to oversize the pack and due to their low energy density you end up at a disadvantage. High power lithium cells have a flat discharge voltage, under heavy loads it can even increase due to internal heating reducing the internal resistance. Their internal resistance is also very competitive with ultracaps so there is no advantage to using ultracaps, yet. On Thu, Aug 14, 2014 at 10:09 AM, Ben Goren via EV ev@lists.evdl.org wrote: As hemp makes a comeback in the U.S. after a decades-long ban on its cultivation, scientists are reporting that fibers from the plant can pack as much energy and power as graphene, long-touted as the model material for supercapacitors. They're presenting their research, which a Canadian start-up company is working on scaling up, at the 248th National Meeting Exposition of the American Chemical Society (ACS). David Mitlin, Ph.D., explains that supercapacitors are energy storage devices that have huge potential to transform the way future electronics are powered. Unlike today's rechargeable batteries, which sip up energy over several hours, supercapacitors can charge and discharge within seconds. But they normally can't store nearly as much energy as batteries, an important property known as energy density. One approach researchers are taking to boost supercapacitors' energy density is to design better electrodes. Mitlin's team has figured out how to make them from certain hemp fibers—and they can hold as much energy as the current top contender: graphene. http://phys.org/news/2014-08-hemp-nanosheets-topple-graphene-ideal.html The full article gives energy density at 12 Wh / kg, which, if I have my figures right, is an order of magnitude shy of CALB and similar popular BEV batteries. Still, I imagine that's more than enough for a quarter mile, and I can't imagine what supercapacitor discharge rates will mean for the drag racing crowd. A supercapacitor-powered dragster could well mark the end of hydrocarbon-based racing. I can also imagine hybrid battery / supercapacitor systems, if these become affordable, even if energy density doesn't significantly improve. Use a supercapacitor with just enough Wh to go all-out for a dozen seconds to power the motor and to accept regen charge, and have a battery just barely capable of continuous discharge at freeway speeds uphill charging the supercapacitor. The battery can be optimized for capacity and density (and price) without worry about discharge rates. The supercapacitor is already optimized for discharge; it just needs to be big enough to hold enough to get up to speed. Cheers, b -- next part -- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 801 bytes Desc: Message signed with OpenPGP using GPGMail URL: http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140814/97d7ed04/attachment.pgp ___ 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) -- www.electric-lemon.com -- next part -- An HTML attachment was scrubbed... URL: http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140814/337cb467/attachment.htm ___ 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)
Re: [EVDL] CALB bolt terminals getting hot -
From: Danpatgal via EV ev@lists.evdl.org ... several of them were around 33C, in a grouping, maybe 6 or 8 posts adjacent on the most positive side of my pack. Posts just a few cells more negative were much cooler, maybe around 26C or cooler. That doesn't seem like much! In fact, that amount could be explained by emissivity error of the tempgun. I've seen them shoot the same mercury-thermometer temperature as much as 10C different between reflective and non-reflective surfaces! Tempguns are notoriously wild, unless you're sure you're measuring things with *exactly* the same emissivity. I'd try it with a contact thermometer before getting too concerned. And then, I wouldn't worry if the differential was 10C or less. Compared to those on pasteurized milk, children who received raw certified milk had better weight gain and greater protection against rachitis. -- Ron Schmid Jan Steinman, EcoReality Co-op (Send email to qu...@bytesmiths.com to get a random quote, or quo...@bytesmiths.com to get 50 random quotes. Put a word in the Subject line to filter for that word.) ___ 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)
Re: [EVDL] CALB bolt terminals getting hot -
#phones Google Phone (919) 631-1451 Cell (919) 513-0418 Desk michael.e.r...@gmail.com michael.e.r...@gmail.com -- next part -- An HTML attachment was scrubbed... URL: http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140814/f7dc57c4/attachment.htm ___ 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)
Re: [EVDL] CALB bolt terminals getting hot -
On Aug 13, 2014, at 2:20 PM, Danpatgal via EV ev@lists.evdl.org wrote: I am using 38x130 ah CALBs in my Lectric Leopard and have had a too hot ( 40C) warning on my BMS come on a few times in the last month or so. Do you get it when driving? I have the Elithion Pro BMS. My to hot warning comes on sometimes when the cells sit in the direct sun. I don't have a cover over them; just plexiglass. corbin Today, after a longer stretch of accelerating uphill to home, I checked some of the battery posts. Measuring with a laser sensor, several of them were around 33C , in a grouping, maybe 6 or 8 posts adjacent on the most positive side of my pack. Posts just a few cells more negative were much cooler, maybe around 26C or cooler. I checked the bolts to make sure they were tight, and didn't notice any real problem with the connections being loose. My only other thought is that perhaps (as has been discussed in other threads), these connections have corroded over time ... adding a little resistance layer (I didn't initially polish or use Noalox on those) that is now finally heating up. I am also using the original copper straps with steels M8 bolts. Are others noticing this kind of heat with the lithium cell terminals? Aside from just cleaning the terminals and putting on some Noalox, might there be other things to do? I installed these in Sep. 2012, so they are not quite two years in service. Thanks - Dan - Dan Gallagher http://www.evalbum.com/3854 -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/CALB-bolt-terminals-getting-hot-tp4670981.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)
