Yes, I am familiar with some of those guys from endless sphere, but they are young males. You remember what that was like right? Completely invulnerable, more testosterone than brains, get a good laugh out of almost burning the house down...besides they likely all rent and they are using small packs so no big loss. They are also using high specific power lipo (lithium polymer) cells which are much more fire prone than LiFePO4. "live for physics" some time back gave good "golden rules" for using lipo cells:
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=9170&start=0#p142304 Several people over on diyelectriccar deliberately severely overcharged LiFePO4 cells and posted video showing them smoking but not catching fire. Quite a few people use a version of Lee's "batt bridge" to watch for pack imbalance, and charge LiFePO4 cells to 3.45V or lower with no bms. David N. who sometimes posts here has been doing that without problems for a few years. That method is popular with the "bottom balancers", who are concerned they will someday run their pack down to zero SoC and want to prevent reversing a cell or cells so balance them all to the same voltage near the discharge end of the curve, say 2.5V, and charge their lowest capacity cell to 3.45V or lower. A number of methods work, some just require more diligence and discipline than others. I think it is easy to become complacent after years of no problems, then as the pack ages there is the possibility that some cells start developing high internal resistance or loose some capacity resulting in eventually overcharging one. That's why I'd rather have a bms with HVC and LVC, and of course almost everyone uses a charge counter so they know the SoC of the pack. Mine is set to repeatedly flash "LOW CHARGE" at 35% SoC. Most people make a mistake when they are just getting started with charging cells and are still figuring out how it all works, what to check, and how fast voltage changes on the exponential parts of the curve, during charging and discharging. That is why for years people have been saying "stay away from the ends of the charge/discharge curve". -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Success-tp4675905p4675967.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. _______________________________________________ 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)
