That, or your meter is not very accurate in measuring the voltages. The voltage of all 66 series cells (plus cable losses) should add up exactly to the voltage that the charger is supplying. It has been said before that charging to 3.45V is sufficient, so about 228V, but make sure that all cells (esp the lowest and highest) do charge to the same voltage. Do you use a BMS to make sure all cells are at the same limit and stay below 3.5V each?
Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: cwa...@proxim.com Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of John Lindsay via EV Sent: Thursday, September 25, 2014 6:29 PM To: Buddy Mills; Electric Vehicle Discussion List Subject: Re: [EVDL] LiFePO4Charging Read the voltage drop across the cables connecting the batteries. The missing volts equal the charge current multiplied by the total resistance in the connections and cables. Otherwise known as Ohms Law. You may have some bad connections. John Lindsay > On 26 Sep 2014, at 10:50 am, Buddy Mills via EV <firstname.lastname@example.org> wrote: > > I thought I understood how to charge my 9 month old LiFeP04 but know I am > doubting my process. So I will lay it out and see what feedback the battery > gurus here can suggest. > > I have 132 60AH batteries in 2P66S. So I am going to call this 66 batteries > at 120AH. Specs call for 3.6 volts max, so 66 in serial is 237.7 volts. I > don't want to push them so I set the max voltage at 231volts charge which > brings me to approx 3.5 volts per battery. Now in real life once it is at > this 231 volts for the string each individual battery voltage is approx 3.34 > volts +/- 0.10 volt. Even at the plus side of that each battery would be > 3.44 volts or 227.04 volts for the string. So how is it that my charger > string voltage is reading 334 - 335 volts while each battery is reading > 3.34? Does it matter if the total voltage is over the max (66 X 231) as > long as the individual voltage is less 3.5 volts? Should I set my BMS > charge voltage cutoff higher and just leave each cell set at the 3.5 volts > max. Hope I am making sense. > > > > Thanks in advance for any feedback, > > > > Buddy Mills > > <mailto:buddymi...@cox.net> buddymi...@cox.net > > > > Look mom, no gas. <http://www.evalbum.com/2887> http://www.evalbum.com/2887 > > > > Disclaimer: No animals were harmed or killed in the process of writing this > email. Any stories to the contrary are, for the most part, either fictional > or greatly exaggerated. > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140925/1b32 3f2f/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) > _______________________________________________ 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) _______________________________________________ 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)