Hi Michael and All, My Volt pack has kept itself within 1/100th of a volt/cell of each other in 5 months and who knows how long before I got it. Using a Lightobject wthr meter EVTV uses to keep the voltage within bounds of 5%-95% shutting off charge, discharge along with multiple LeeHart battbridges to alert if something is going wrong which can also cut off the pack by a phototransistor circuit should do fine. Not sure if he was only using their version of the wthr meter as one should always have 2 systems in case one fails. But he did say he programed the cut off wrong is what I got out of the post ,meaning human error. As a full BMS has a lot more failure points thus not fool proof either, my version should do fine as if starting to overcharge/discharge the Battbridge will detect it if the wthr meter alarm/shut off fails . Aftermarket BMS don't have the best record either and cost 30-50% of the battery price of used quality cells their value isn't what others say. Now if we can hack the stock BMS from the EV's the batteries come from would be another story. But until then of aftermarket systems get better, cheaper I'll stick my way. BTW in case people are interested 21kwhrs of Tesla modules at about $4500 are on Ebay under electric vehicle batteries. Jerry Dycus From: Michael Ross via EV <[email protected]> To: paul dove <[email protected]>; Electric Vehicle Discussion List <[email protected]> Sent: Sunday, November 8, 2015 1:18 PM Subject: Re: [EVDL] Rickard's EVTV let the smoke out> overcharged pack fire blew up I think the self discharge complaint is growing less all the time - with good quality cells. But really large packs beg prudence. A golf cart packs, like Jack sells which will be operated by non EV types, gets real benefit from his bottom balancing and sealing. The little 10AH 48V packs used in light EVs and bikes are a analogous - small, operated by the unwashed.
Whatever is done, a really dependable charge cut off function must be part of any system. Our ability to evaluate cell quality, and BMS quality and function is still suspect (particularly for the cash strapped DIYer; as opposed to a large company with real money to command action) so I expect this argument to continue, and it should. On Sun, Nov 8, 2015 at 1:03 PM, paul dove via EV <[email protected]> wrote: > There is no evidence thus far to support that theory. > It could have been a pack he uses to power his bench or one he was > charging to put in a car. > He does all sorts of crazy experiments like test the sag while pulling > 1000 amps. > From the article it didn't sound like it was in a car. > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20151108/04667ad5/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
