For range... take the weight of the vehicle and divide by 10. 3200lb car 320 watt hours per mile.
Sent from my iPhone > On May 11, 2020, at 10:33 PM, Lawrence Rhodes via EV <ev@lists.evdl.org> > wrote: > > I have just taken the first step and purchased near a hundred cells. My > experience is with lead batteries. I want to do it right but I don't want to > push my system. It is a 40amp controller 48-72vdc. the motor is 3kw. I live > in San Francisco and want a little boost for my recumbent. These cells will > put out 60 amps according to the data sheet. 1 string may be enough but I > don't yet know if the BMS I am looking at will support more than one string. > I don't know if the BMS and charger will talk to each other. It would be > nice to get a complete solution. I also don't know if 2.5amp hour 72v system > will have enough range. I have so many questions. Lawrence Rhodes...a good > book might be in order... > > > > > > > On Monday, May 11, 2020, 6:47:14 PM PDT, Marco Gaxiola <mgaxi...@gmail.com> > wrote: > > > > > > A few questions Lawrence; > > Is the charger you'll use programmable to a desired cut off voltage? > > If so, What is the Max operational voltage for your controller? Maybe you can > make your array with as many cells in series as closest to max controller > operational voltage when cells at max. be top of charge. Usually this would > only happen right at the end of a full charge and would last only a few > minutes. But the more cells in series; the more energy and less current in > the system. > > If your charger has a fixed top off voltage, you technically have to attach > to that voltage and match the right # or cells in the series circuit. > > I'm assuming you are using LiFePO4 chemistry because of the 3.3V you > mentioned. That chemistry, typically has a max V of 3.65V (3.7V some cases > although I wouldn't recommend it). Typical 72V controller can support up to > 90V operational (100Vish Max, depending on internal caps). > > That would be 90/3.65 = 24 Cells in series, then as many strings in parallel > >> 87.6V charger cutoff voltage. Hope this can help. > > > Marco Gaxiola > >> On Mon, May 11, 2020 at 1:50 PM Lawrence Rhodes via EV <ev@lists.evdl.org> >> wrote: >> I am having trouble deciding weather 20, 21, or 22 batteries are the right >> series string for a 72vdc battery. for a 3.7 volt battery 20 seems to be >> right. However I have A123 batteries and nominal is 3.3vdc. Videos on >> YouTube are inconclusive. Sellers details not complete. Any advice >> appreciated. I'd like to run 1 or two strings for a small ebike battery. >> The controller only draws 40amps. Lawrence Rhodes >> >> _______________________________________________ >> 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) > _______________________________________________ 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)
