There is quite a bit of information here, http://liionbms.com/php/bms_options.php
and here, http://liionbms.com/php/bms-selector.php http://liionbms.com/php/battery_modules.php This is the main page that has several different categories listed, including motor controls http://liionbms.com/php/index.php On Thursday, July 24, 2014 1:14 AM, Ben Goren via EV <ev@lists.evdl.org> wrote: On Jul 23, 2014, at 3:45 AM, Ben Apollonio via EV <ev@lists.evdl.org> wrote: > On the contrary. Tesla cells discharge at a very LOW current. When you have > 85kWh of battery, you only need 3.5C to make 300kW, and C/5 to cruise at > 55MPH. Even the 120kW 'supercharger' tops out at about 2C (for the smaller > 60kWh battery). > > I would hazard this is why larger cells are not designed for large currents. > RC cars are designed to run for 2 minutes and are trying to maximize > power/weight. Most real world applications need more capacity and have to > optimize energy/weight, so there's significantly less market for cells at > 100Ah and 300C (not to mention that you would then have to find a way to > manage 30,000 amps!!). You would seem to be correct. Judging by the battery packs I've found being sold for BEVs at the types of places listed as authorized dealers for Netgain and HPEVS, it looks like the assumption is that you're going to be throwing lots of batteries at the car so you don't need to worry much about individual battery discharge capability. I haven't by any stretch of the imagination done any sort of thorough investigation, but the first pass suggests that something along these lines might be the direction I'd have to head in: http://www.all-battery.com/tenergy3.2v1300mah4.16whlifepo4ifr18650prechargeablebattery-30065.aspx It's a single 18650-sized cell (Wikipedia says that's what the Tesla uses; looks to be a bit bigger than a AA) with a 1.35 Ah capacity. If my math is right, to get to ~10 kWh I'd need 10000 kWh / (1.35 Ah * 3.2 V) ~= 2300 cells. Each cell supports up to 10 A continuous discharge...and 23,000 A is not only waaaay more than I'd need, it sounds positively terrifying. 2300 * 3.2 V ~= 7,400 V, which is again scary overkill -- and, obviously, they'd have to be wired in combinations of series and parallel banks to get that down to a reasonable range. Make the math easy, and do it as 50 packs of 45 batteries each for 144 V, 9.7 kWh, and <don't think about it> maximum current draw...and ~200 pounds of batteries. And about $9000 in batteries (almost 4x the cost of 144 V of CALB 40 Ah packs), before the cost of the hardware to wire them up and the time that would go into doing the wiring. At that point, what I was thinking of as the advantage of a small pack is long gone. This kind of a n homebrew system still might make more sense for this particular project than an off-the-shelf product, but it would mean a bunch of re-thinking.... Has anybody here already done this type of research? Is there a graceful way to get to high current capacity with a small pack size? Maybe a different size cell to build the packs from? I'm obviously not an expert on battery technology.... Thanks again, 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/20140723/295e652d/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) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140724/c0d2a649/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)
