Hi Dave etc, It's on the data sheet from A123 racing, 116 south St., Hopkinton, Mass 01748 "recommended float charge voltage: 3.45V" on the 26650 cell 2.3ah 3.3V. Best Regards, mark www.REEVA.info community service RE & EV's From: David Nelson <[email protected]> To: Mark Hanson <[email protected]>, "[email protected]" <[email protected]> Subject: Re: [EVDL] LiFePO4 float charging Message-ID: <-3284242415328503278@unknownmsgid> Content-Type: text/plain; charset=ISO-8859-1 Who at A123 told you that? Do they have test data of holding a cell at 3.45V for momths or years and no issues? Did they compare that with holding the cell at 3.40V or 3.38V? What, really, is the energy storage improvement by using the higher voltage assuming no adverse effects? If I were in your position I wouldn't buy that. I'd do my own testing. I'd put a cell on at the 3.45V in a constant temperature environment and let it sit at that terminal voltage for a few hours and then measure any temperature difference between the cell and ambient. If the cell is warmer then it is being overcharged. Also, carefully measure the current going into the cell. If it is above 0?A it is being over charged. Do the same tests at 3.40V and 3.38V and compare results. If you capacity test the cells after being held at the different float voltages I'm sure you will find that there is a minuscule difference in energy storage. Furthermore, given that the NASA research summary I read a couple of years ago found that the calendar life of all Li based rechargeable batteries was shortened when left at 100% SOC as compared to a lower SOC, do you really need the cells at 100%+ all the time? Whatever you do please report your results. David D. Nelson http://evalbum.com/1328 http://www.levforum.com -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20130301/24efe507/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)
