I had a loose connection on my pack. It heated the cell to failure before I found it.
Sent from my iPhone > On Sep 30, 2019, at 10:57 PM, Mr. Sharkey via EV <[email protected]> wrote: > > Time to turn up the dial on the technical channel. > > After converting my car to a lightly-used set of Thundersky 160's, I've > finally gotten around to having some thermal images taken of the cells after > running the car up to temperature. My purpose was to make sure that none of > my cell interconnect wiring (copper strap stock) was heating up. What I found > was somewhat unexpected. One of the 38 cells was showing an elevated > temperature from the rest. > > First, the IR image of the right-hand half of the pack, taken from behind the > car. the suspect cell is at the center cross-hairs: > > http://www.westlanetv.org/~sharkey/evgfx/IR_0677.jpg > > A close-up of the cell, looking from the front of the pack. It's been > photoshopped to blend the IR image with the visible image to provide some > perspective of the actual appearance: > > http://www.westlanetv.org/~sharkey/evgfx/Hot_Cell_2.jpg > > The car ran a 15 mile trip at about 55 MPH, pulling 100 - 125 amperes most of > the way. A couple of 275 - 300 amp sprints pulling out into traffic, etc. > Photos were taken immediately thereafter. > > All of the cells had been carefully (manually) balanced a few days before the > photos were taken. During balancing, this cell was about 15 ampere-hours > lower than most of the rest of the pack, but not the lowest of the 8 cells > that needed attention. It came right up with a balancing charge. None of the > other cells showed any variance in temperature in this series of photos. > > Questions for the list: > > The cell isn't actually "hot" but it's obviously warmer than the rest. What's > everyone's take on this one cell warming up? Can I just assume that it may > have higher internal resistance, and therefore more heating under load? Is > the heating indicative of a coming (perhaps spectacular) failure? > > I've got about 1,600 miles on this new pack, and it seems to be performing > well. I'd like to keep using it in this configuration, but if it seems risky > to continue loading this one cell, it ~could~ be jumpered out of the pack > (not my first choice). > > Opinions or advice? > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > ARCHIVE: http://www.evdl.org/archive/index.html > INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
