Interesting looking trike. Looks very handy for local trips and shopping
-------- Original message -------- From: Michael Ross <michael.e.r...@gmail.com> Date:03/08/2014 2:35 PM (GMT-05:00) To: Electric Vehicle Discussion List <ev@lists.evdl.org> Subject: Re: [EVDL] NiMH availablity ... Hi winfield, I have a number of reasons. One, I want to learn. I prefer to do things myself, and DIY'ing a BMS seems unlikely for a number of reasons. I like to understand the underlying details. This is teaching me alot. Who knows what use it will be? Doesn't matter to me. Second is money and scale. You all clearly have a different way/scale of thinking about this. I don't particularly like cars, even automotive EVs squander power (relatively speaking), they remove physical activity from our lives which is a major problem if you want to live long and be healthy as I do, I like to live below my means by being creative. I doubt if I will ever convert a car. My vehicle gets an estimated 1800MPG (calculated equivalent) and is a pedal assist velomobile with a 1 HP motor. You all sometimes spend more on BMS and power supplies than my whole rig which is an Organic Transot ELF. The stock ELF is really for getting groceries,. I use mine to commute 25 miles each way to work and would like to extend the range as much as possible. This pack is my third, all are 48V (charge with 60V) on is 10Ah (good for 10 to 14 miles), the other 20 Ah (will just do 125 miles) and I picked up a salvage pack of 24 40Ah Thundersky cells for $100 (could get me another 50 miles for a potential 90 mile range). The 40Ah pack had a bunch of those little Australian shunt cell balancers (E bike stuff), some of which were damaged. I want a BMS, that I understand and trust (hard to find with Chinese battery packs) and can afford; or, since it is possible, and perhaps even better (excluding considerations of labor), I want no BMS at all. I won't claim this makes sense, because I have used this as an excuse buy a number of bit sand tools (anyone else every do that?). I could probably buy a BMS with the $, but now I have the tools. I am here in EVDL because in Li batteries interest me a lot, and this forum is where a lot of sharp people also care about batteries. On Sat, Mar 8, 2014 at 11:38 AM, winfield...@yahoo.com, < winfield...@yahoo.com> wrote: > Why not just use a BMS? With the $$$ you are spending on Li batteries, it > seems wise > > > > -------- Original message -------- > From: Michael Ross <michael.e.r...@gmail.com> > Date:03/08/2014 11:11 AM (GMT-05:00) > To: Electric Vehicle Discussion List <ev@lists.evdl.org> > Subject: Re: [EVDL] NiMH availablity ... > > Marcus, > > A reasonable question. For LFP I think you want to go lower like 1.5V > maybe. I think a lot of the historically acceptable target voltages are > arbitrary (adopting a RIckard opinion). 1.5V might even be higher than > necessary. 1.5V is perhaps a reasonable cut off voltage for a bottom > balanced LFP pack. I don't think there is anything definitive about this. > > Voltage being such a crappy surrogate for State Of Charge you definitely > want to be far away from the flat part of the V/SOC curve where small > changes in V are large changes in SOC. Around 1.5V there a la much greater > change in V for a small change in SOC. > > When BB'ing you want a low open circuit voltage....the way I have seen it > done, the cell is loaded down, and at a target voltage the load is lifted, > the voltage recovers, the load is added, the load is lifted, again and > again until the voltage settles where you want it and the recovery is very > small. Best to automate this if you can. You can throw a 20 foot rebar > out on the sand and run 1000A through it if that works for the cell in > question and the C rate you desire. > > I think if you put two cells in parallel, and you run them to a low target, > you have the same old issue that BB'ing is trying to cure maybe? If one > cell goes empty before the other , the other cell has significant charge > left in it, then a loop gets going between them lots of current flows > backwards through the empty cell and one or both of them are cooked. > > I think. FWTW > > > > > On Sat, Mar 8, 2014 at 7:04 AM, Marcus Reddish <marcus.redd...@gmail.com > >wrote: > > > Am I crazy or could bottom balancing be done at 3V with all the cells in > > parallel? They will all be perfectly balanced together at 2.75V or > > whatever you chose. Use a JLD and contactor with a resistive load to get > > down to the target voltage. Reconnect them in series and charge. > > > > Please note that hooking them in parallel for balancing would only work > at > > the extremes (low for BB, high for TB). If you hook them in parallel at > > half full (3.2v) they won't be balanced at either extreme. Obviously, > this > > only would work for groups of individual cells, not pre-made modules. > Are > > there any issues with this approach? > > > > > > On Fri, Mar 7, 2014 at 1:36 PM, Michael Ross <michael.e.r...@gmail.com > > >wrote: > > > > > There is a real possibility that BB'ing saves you more than you put > into > > > it, but this is pretty speculative. > > > > > > There are hidden costs too - I have to come up with a resistive load > than > > > can dump significant amps (rebar and an 200Ohm wire wound). Some > people > > > just jack up the vehicle and spin it, but that is unappealing to me > when > > I > > > can always use an excuse to weld something. You need contactors, and > > > JLD404s and shunts, stuff like that. Once you have it you can do more > > > packs. The tools are general purpose. > > > > > > I investigated DIY BMS and this all seemed easier. > > > > > > > > > > > > > > > > > > On Fri, Mar 7, 2014 at 3:06 PM, EVDL Administrator <evp...@drmm.net> > > > wrote: > > > > > > > On 7 Mar 2014 at 3:08, Michael Ross wrote: > > > > > > > > > So there is an appeal to bottom balancing in terms of life, cost > > > > > (ignoring labor, but we are DIY'ing so that is ignored always), and > > > > > ease of use. > > > > > > > > I see your point, but I don't agree that DIY labor cost is "ignored > > > > always." > > > > OK, it's not like I'm paying a mechanic, but every hour I spend under > > the > > > > hood or under the car is an hour I don't have for other things I like > > > doing > > > > just as much or more. > > > > > > > > But hey - if you have the time and you enjoy it, why not try? > > > > > > > > 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) > > > > > > > > > > > > > > > > > -- > > > Put this question to yourself: should I use everyone else to attain > > > happiness, or should I help others gain happiness? > > > *Dalai Lama * > > > > > > Tell me what it is you plan to do > > > With your one wild and precious life? > > > Mary Oliver, "The summer day." > > > > > > To invent, you need a good imagination and a pile of junk. > > > Thomas A. Edison< > > > http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> > > > > > > A public-opinion poll is no substitute for thought. > > > *Warren Buffet* > > > > > > Michael E. Ross > > > (919) 550-2430 Land > > > (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#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/20140307/5fa24547/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) > > > > > > > > > > > > -- > > Marcus Reddish > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: < > > > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140308/fba10f4c/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) > > > > > > > -- > Put this question to yourself: should I use everyone else to attain > happiness, or should I help others gain happiness? > *Dalai Lama * > > Tell me what it is you plan to do > With your one wild and precious life? > Mary Oliver, "The summer day." > > To invent, you need a good imagination and a pile of junk. > Thomas A. Edison< > http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> > > A public-opinion poll is no substitute for thought. > *Warren Buffet* > > Michael E. Ross > (919) 550-2430 Land > (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#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/20140308/13a27b04/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) > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140308/743b07a0/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) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison<http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#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/20140308/9ac39cee/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) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140309/57754f4a/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)
