Thanks Bill, sorry I'll try and give you more information. I'm using a Zivan NG3 charger and don't have a BMS at the moment, just a bunch of QNBBM cell balancers.
Previously I stopped the charge manually when the Curtis was saying 100%. The Zivan also displays a charging progress and it would also be at 100%. But lately the Curtis is saying 30% when the Zivan is showing 80% complete and some of the cells are starting to jump up to 4V during that phase of the charge. Whenever a cell goes over 4V I've been stopping the charge and allowing the cell balancers to even out the pack again. Is there anything other information I should be providing? Thanks for your help. Matthew It all came out of a working car and has been fine until recently when the pack 07966 806 727 On 7 August 2017 at 15:13, Bill Dube via EV <[email protected]> wrote: > You have not given quite enough information about your system to fully > understand your issue. > > However, to fully charge your 25 LFP cells to 100% SOC, your charger > should shut off at a voltage of a minimum of ~3.45 volts on all cells. > The full-charged pack voltage should be 87.5 volts, or a bit more. > > 3.6 to 3.8 volts on the highest cells is where your BMS should be set to > reduce the output of your charger. You should not be going over ~3.8 volts > on any cell. > > Your charger should be controlled by your BMS somehow, hopefully. > > Like I said, we need a bit more information on your system to understand > exactly what your problem really is. > > Bill D. > > > On 8/7/2017 12:53 AM, Matthew Quitter wrote: > >> Thanks guys... but if the charger is turning off at a fixed voltage how >> do I get more power into the pack? >> >> >> On 7 Aug 2017, at 05:02, Bill Dube via EV <[email protected]> wrote: >>> >>> I agree. Voltage on LFP cells is useless for determining the SOC. >>> The voltage is very constant except at near 100% SOC and at 0% SOC. >>> You really need information about the middle, and voltage doesn't give >>> any clue about that. >>> >>> You need to count the amp-hours, like with an E-meter or a Cycle-Analyst. >>> >>> Bill D. >>> >>> On 8/6/2017 7:00 PM, Willie via EV wrote: >>>> >>>> >>>> On 08/06/2017 07:38 PM, Matthew Quitter via EV wrote: >>>>> Hi Guys, >>>>> >>>>> My 1238-6501 Curtis controller gives very different SOC % for similar >>>>> voltages. >>>>> >>>>> For example I've recorded a pack voltage of 82.2 and had the Curtis >>>>> show >>>>> 22%, 31%, 43%. >>>>> >>>>> The pack is made up of 25 Thundersky 160Ah batteries. >>>>> >>>> With LFP cells, you can't accurately infer SOC from voltages in the >>>> middle of the range. The voltage/SOC curve is too flat. >>>> _______________________________________________ >>>> 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) >>>> >>>> >>>> _______________________________________________ >>> 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) >>> >>> > _______________________________________________ > 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) > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20170807/a719ea64/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)
