Update.... and EV grin. I took the VW bug out for the first serious drive with Lithium last night. WOW.
Before -- with the 12 volt AGMs. I was getting maybe 280 amps peak battery amperage on a freshly charged pack, dropping to less than 100 amps after 5 miles or so. Pathetic performance (lots of driving on the shoulder). With the 100AH, 72 volts of CALB lithium, I was regularly getting 200 amps on acceleration, and I got 370 amps peak once (should probably not do that too much for the health of the batteries). The alltrax 450 never even got warm, with it's new heat sink and cooling fan. It's peppy now... way more than a ICE VW bug. 30mph up hill, and can pull out onto the highway just fine (highway being the 45mph road -- not 75mph freeway). And... the motor (6.7" series) is actually running cooler than before as well. I think because the controller is able to keep the speed up, the motor RPM is not dropping like it was before, so it's actually cooling better with its internal fan. And, it takes less time to climb the hill when you can keep up 30mph instead of 15. After climbing a two mile hill at 250+ battery amps most the way, it was hot but not too hot to hold onto. I kept it in 2nd up to about 40, then switched to 3rd for more power on the highway. 1st is able to peel out in the dirt. I'm sure that driving it like that doesn't help the efficiency, but it's way more fun that it was as a lead sled (it's also about 400lbs lighter). One thing.... 50mph around curves is a little scary... something to do with standard suspension and brakes of a '73 VW bug.... I only took 20AH out of them, because I don't have the BMS connected to the controller yet, but this weekend, I'll do a full range test with the BMS operating. Makes me want to get lithium for my Ford Courier conversion now. Z On Fri, Aug 30, 2013 at 8:32 AM, Zeke Yewdall <zyewd...@gmail.com> wrote: > Yes... those calculations make sense... at the 200 to 300 amp range, I'm > getting about 10 to 15 minutes at most before it start getting serious > current limit... which implies that the batteries are actually functioning > per specs... just that I'm wanting more power than they can deliver. > > Z > > > On Thu, Aug 29, 2013 at 11:56 PM, Don Bradley <sonom...@sonic.net> wrote: > >> Hi Zeke, >> In looking at your battery spec, it indicates the 12 volt battery >> is 391 watts per cell constant discharge for 15 minutes to 1.67 volts per >> cell. If I divide the 391 watts by 2 volts per cell, it comes out to 195.5 >> Amps for 15 minutes for the voltage to drop to 1.67 volts per cell. >> >> You mention that you are drawing 300 battery Amps at times, which is 100 >> Amps more. looking at the chart indicates 505 Watts constant discharge per >> cell for 10 minutes. at 2 volts per cell, that 's 252.5 Amps. >> >> >> Does it seem reasonable that with high current draw(acceleration, going >> up a hill, high speed) you don't have much time before your batteries are >> discharged? >> >> Don >> >> >> On 8/29/2013 12:08 PM, Zeke Yewdall wrote: >> >>> Sorry... I posted the details a long time ago. >>> Photo of it on top of the mountain today: >>> http://sphotos-a-lax.xx.fbcdn.net/hphotos-ash3/1240063_ >>> 605592482816967_962234180_n.jpg >>> >>> For current reference: >>> It's a 1973 VW superbug with the e-volk #2 kit... >>> http://www.e-volks.com/about2.html? >>> >>> It was an "interesting" conversion that was virtually undriveable when I >>> first got my hands on it. Some odd design choices too (for example, the >>> original starter motor was left attached to both the ignition key and the >>> transmission... so everytime you "started" it, the 12 volt starter motor >>> would rev up briefly -- I thought it was sending a surge to the main >>> drive >>> motor when you started it, but then found that. Hmm......... could >>> probably lose 10lbs by taking that out. >>> >>> Controller is the Alltrax 7245 >>> Motor is 6.7" series DC by D&D direct coupled to transmission -- in this >>> case, I can shift through all the gears just fine without a clutch, >>> except >>> 1st I have to rev the motor a tiny bit to get it in there if it's moving >>> already and I'm downshifting from 2nd. >>> >>> Batteries are 12 volt 100AH AGM UPS batteries >>> http://www.npstelecom.com/pdfs/Dyn_UPS/UPS_12-370.pdf >>> 72 volt nominal system, 74lbs each (444lbs total) + auxiliary battery >>> (which is a standard starter battery instead of a deep cycle... ugh). >>> Those batteries look like pretty high rate batteries... no real idea on >>> how old they are though -- they are used taken out of UPS systems I >>> think... >>> >>> I've added a Xantrex AH meter and some circuit breakers and such, and an >>> Elcon 1200 watt charger. No DC-DC, separately charging the 12 volt >>> auxiliary battery. >>> >>> It's incredibly fun to drive for a few miles now, till the current limit >>> kills the performance... but not quite long enough range to be actually >>> useful yet.... 7 or 8 miles is a long as I'm getting before current limit >>> is shutting it down to snail pace. >>> >>> What do people think of the Concorde AGM batteries? Wondering if that >>> might be an option for new ones. A bank of PVX-1290T would have a 1 hour >>> rate of 79AH, for the same weight as the existing bank. >>> I'd like to do a bank of GNB 100AH lithium batteries, but that would >>> roughly double what the client paid for the car (they got a great deal >>> anyway, just the restored glider was worth what they paid, even if it >>> hadn't had any EV stuff put in yet). Though... that's only about twice >>> as >>> much as a good AGM bank, so maybe it doesn't make sense to do lead. I >>> want >>> to have good options to present to them though. >>> >>> Z >>> >>> >>> >>> >>> On Thu, Aug 29, 2013 at 12:39 PM, EVDL Administrator <evp...@drmm.net >>> >wrote: >>> >>> On 29 Aug 2013 at 11:51, Zeke Yewdall wrote: >>>> >>>> It seems like it's staying on till about 1.7vpc, and that's probably >>>>> not good for the batteries to drop below that, right? >>>>> >>>> >>>> The rule of thumb for lead is that you stop (or reduce load) when the >>>> battery voltage under load falls to 1.75 volts per cell. You hope that >>>> will >>>> prevent cell reversal. It doesn't always. >>>> >>>> As for where to go, I'd start with replacing the one battery that read >>>> low. >>>> That's probably just a quick fix, though. >>>> >>>> Some kinds of AGMs can deliver huge currents with aplomb and are >>>> suitable >>>> for fast, short range EVs. Others are hardly much better than the >>>> infamous >>>> flooded marine batteries that die in a few months of such use. But you >>>> don't say what the batteries are (or if you did I've forgotten). >>>> >>>> Could you remind us of such matters as vehicle weight, what batteries >>>> you're >>>> using, what motor, what controller? >>>> >>>> This is a Beetle, right? I'm pretty sure I remember folks back in the >>>> late >>>> 1970s and 1980s building Beetles with 72v golf car battery packs. They >>>> gave >>>> up the back seat to batteries, of course. However, I checked the EV >>>> Album >>>> (searched with startpage.com, as Evalbum search wouldn't work for me) >>>> and >>>> found only this one, I guess originally converted by Lawrence Rhodes : >>>> >>>> http://www.evalbum.com/1466 >>>> >>>> And another with 8v golf car batteries : >>>> >>>> http://www.evalbum.com/1689 >>>> >>>> David Roden - Akron, Ohio, USA >>>> EVDL Administrator >>>> >>>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = = >>>> EVDL Information: http://www.evdl.org/help/ >>>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = = >>>> Note: mail sent to "evpost" and "etpost" addresses will not >>>> reach me. To send a private message, please obtain my >>>> email address from the webpage http://www.evdl.org/help/ . >>>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = = >>>> >>>> >>>> _______________________________________________ >>>> 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) >>>> >>>> >>>> -------------- next part -------------- >>> An HTML attachment was scrubbed... >>> URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/ >>> attachments/20130829/53d23bc1/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) >>> >>> >>> >> -- >> Don Bradley >> PO Box 141 >> Forestville, Ca. 95436 >> >> Maker of Signal Generators for Chladni Plate Tuning >> >> _______________________________________________ >> 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) >> >> > -------------- next part -------------- An HTML attachment was scrubbed... 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