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Re: Mavins motor?s bearings ([EMAIL PROTECTED]) ---------------------------------------------------------------------- Message: 1 Date: Thu, 13 Sep 2007 11:56:24 -0700 From: "Cor van de Water" <[EMAIL PROTECTED]> Subject: Re: [EVDL] Tesla batteries (maybe good news via Valence batteries) To: "Electric Vehicle Discussion List" <ev@lists.sjsu.edu> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset="iso-8859-1" I would expect that each DeWalt pack with its own BMS will do its internal balancing, so I expect that you will get the best results treating each pack as a black box - you would not even need to open the original packs, so warranty is not even voided if you can find a reasonable way to connect to the tabs of the complete pack. With each pack as a module taking care of its internal balance, you will only need to care for the total balance, like when having multiple Lead-acid battery strings, you don't connect individual cells (because you can't get at them) and even if you form high power strings, it is advised to interconnect the strings with thinner wires to allow a slight imbalance between strings to accommodate differences in temperature and chemical mix and such. The thinner parallelling wires will eventually balance the modules without causing undue stresses on a particular module or its BMS. In your drawing: keep all red wires, remove all blue wires and then add a blue wire between the middle 3 red wires. BTW, in order to reduce discharge differences between strings due to different resistance from for example wire length differences, you can best use the top left and the bottom right as places to interconnect your 3 strings, not connect both sides in the middle because then the middle string will suffer most deep discharges. Hope this clarifies. Cor van de Water Systems Architect Proxim Wireless Corporation http://www.proxim.com Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com Skype: cor_van_de_water IM: [EMAIL PROTECTED] Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925 Fax: +1 408 731 3675 eFAX: +31-87-784-1130 Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Osmo S. Sent: Thursday, September 13, 2007 8:56 AM To: Electric Vehicle Discussion List Subject: Re: [EVDL] Tesla batteries (maybe good news via Valence batteries) What is the best way to make parallel-series packs out of Dewalt packs? Does this very artistic sketch of mine make any sense? http://www.havina.fi/dewalt.htm What size the wire making parallel connections should be? Any ideas how the packs should be physically placed to get as short, safe and sensible connections as possible? kiitoksin, Osmo P.S. Jeff, it would be easier to follow the threads if you keep the messages you are replying to in your mails. :) Jeff Shanab kirjoitti 12.9.2007 kello 15.01: > Dewalt packs are connected in series, not of much use for us. You > can't really cut them free and if you rotate them, the cell can be > damaged. > But you could take say 24 such packs as is and interconnect each tab > for balancing and connect the + and _ for power to get a [EMAIL PROTECTED] > module > > My plan is make 12 cell sub-modules (that can be replaced if > necessary.) > 12 of these submodules are in the battery module with bms and can be > interconnected either 6x2 or 4x3 for [EMAIL PROTECTED] or [EMAIL PROTECTED] > with the > same electronics and case. (The case is re-useable, ie not permanently > sealed.) > > _______________________________________________ > For subscription options, see > http://lists.sjsu.edu/mailman/listinfo/ev _______________________________________________ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev ------------------------------ Message: 2 Date: Thu, 13 Sep 2007 11:57:43 -0700 From: [EMAIL PROTECTED] Subject: Re: [EVDL] Mavins motor?s bearings To: ev@lists.sjsu.edu Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes"; format="flowed" > As far as I can tell, the tranny/differential oil was ment to run > freely inside the motor, also around the rotor. Is that possible? > What if there is air instead of oil (should the distance between the > rotor and the stator be different etc)? This is the motor used in my Ranger EVs, which is directly mated to the rear axle. They use an aerospace "Tribolube" instead of normal gear oil, so I guess this is what you engineers call "application-specific". No wonder mavin got them cheap: once Ford stopped making the electric Rangers, there was no use for such an odd-ball motor - they probably still have enough in stock for repairs for the next decade, considering how few of them are on the road. The only people who would find this motor cost-effective would already have a Ranger EV drive train to begin with. ------------------------------ _______________________________________________ EV@lists.sjsu.edu For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev End of EV Digest, Vol 2, Issue 37 *********************************