Hi Cor, Hard to tell, but it looks like a steel stud to me - what other material to use for a stud? Maybe bronze? Stainless? Closer examination - I believe the visible surface of the Belleville washer is chromated and the stud itself. I still vote for the stud to be steel, but it looks to be pressed into a copper component which I mistook for a shoulder. That seems good; the steel allows a high clamping force and in the sandwich you have better conducting copper alloys.
Good quality zinc chromate won't rust, which is why it gets used so much. The color in the image reminds me of a Zn chromated plate. Is the image of the "Classic" pack? I fully agree the washer should not be a current path. the strap or bus should be pressed directly agains the terminal of the cell. Regarding washer flatness I admit to speculating on this. A lot of washers are cheap stamped parts, they have die burrs and are not especially flat. Some are thin and quite flexible. Some have small OD and Large ID under the bolt head. These all sound like negatives to me. If you have a die burrs that is going to concentrate the contact force where spreading it out over more are ought to be better - that is why hardened and ground washers exist. I have a new to me used pack of Thundersky 40Ah cells. It is unlike the others I have with a pretty broad flat to make contact. For example, I am pretty certain that a small SAE SS washer under the bolt head is not going to make a nice uniform contact between the strap and the terminal. I think I will get some larger OD washers for those bolts. Not hardened, because given the aluminum threaded hole, I won't be torquing enough to benefit from that kind of washer. IF the straps were beefier I might not bother with the larger washer, but I think it will be a bit flexible. I will make sure the terminals and straps are clean and dry and use a torque wrench. I may apply the torque wrench again at some later time out of curiosity, but I am betting no further tightening will occur before the limit is reached. On Thu, Jan 9, 2014 at 12:31 PM, Cor van de Water <[email protected]> wrote: > The Classic Prius pack never sees currents above 60 Amps and I doubt > that the material is steel since I have never seen it rust. > The pack is sitting behind the rear seat, so it definitely was not under > water ever, but condensation is possible and more importantly the cells > are not properly sealing. They have a vent on top, but early cells > leaked at their terminals, causing this corrosion from the electrolyte > and therefor the terminals get a buildup of corrosive electrolyte > deposited by the outgassing and leaking. *this* will corrode the bus bar > on the terminals quickly and Toyota's Service Campaign on this issue has > been to rework all Classic packs for free with sealing glue and cleaning > of the bus bars. It took them 2 days on my Prius, back in 2005. > > Cor van de Water > Chief Scientist > Proxim Wireless Corporation http://www.proxim.com > Email: [email protected] Private: http://www.cvandewater.info > Skype: cor_van_de_water Tel: +1 408 383 7626 > -- 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 [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140109/f4f61343/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)
