boB, Yes, the Absorb timer in the FM and MX determine maximum CV time. From FM manual: While the batteries are held at this voltage, the ChgT counter in the Misc menu counts up from zero toward the user-defined Absorb Time Limit. (See pages 44 and 49.) The charger will exit this stage and enter the Float stage if the ChgT timer reaches the time limit, or if the Absorb End Amps setting is reached.
Float V is what ever you programed in Charger Setup. We normally Float at 3.4 to 3.45Vpc, 13.6V to 13.8V for 12V bank. I find that Rebulk is not very important. Float mode can easily replace energy to the battery at the same rate as Bulk/Absorb would without the higher voltage and additional absorb time. It does not take much voltage delta to produce high current. Each sunrise restarts the controller. This is good to produce another Absorb cycle for cell balancing. Larry Crutcher Starlight Solar Power Systems On Dec 1, 2021, at 1:24 PM, b...@midnitesolar.com wrote: Thanks Larry. The information to stop when absorb voltage was reached is like, 10 or more years old and so I don't know if that voltage reach and stop charging algorithm is still used by any BMS's. This is probably why we had to add a logic input to tell the controller to stop charging from the BMS. After the 0.3 hours at Absorb for balancing (which makes perfect sense for a BMS), does the MX/FM then go to float at 3.65V per cell after that ? Does your systems just restart a new bulk/absorb cycle the next morning or do you also do a Re-Bulk if or when battery voltage falls below a certain point ? Also, listening (reading) chat here on what might be needed that may not have been addressed by Li battery, BMS and/or charge controller manufacturers. Thanks, boB On 12/1/2021 12:03 PM, larrycrutcher wrote: > If you stop charging a Li-ion battery when the CV (absorb voltage) is > reached, you may reduce or stop the needed cell balancing time. We have had > customers develop unbalanced series cells from continuous undercharging. > Because of internal cell resistance, one cell will always reach saturation > before others in the group. This can happen at less than 1mv difference. The > more unbalanced a group of series cells are, the sooner one cells voltage > will spike causing over voltage events at a lower terminal voltage. > > Our Li batteries (Elite Power Solutions-GBS and LiFeBlue) can be held at > 3.65Vpc continuously, no problems. We have customers using both MX and FM > controllers for 8 years now. Our recommended setting for the Absorb timer is > 0.3 hours. This allows for cell balancing and for the capacity meter to > recalibrate. Some chargers will stay at CV for several hours. No problems > doing this either as long as cell voltage is lower than 3.8V (LFP chem.). > > Larry Crutcher > Starlight Solar Power Systems > > > > On Dec 1, 2021, at 9:38 AM, b...@midnitesolar.com > <mailto:b...@midnitesolar.com> wrote: > > > > Depends on the requirement for the BMS. > > Usually, but not 100% always, the requirement is to get the voltage up to > "absorb" and then stop charging. > > Just set the min and max times very low, like 1 minute and that should > satisfy that one. > > I do not remember if the MX60 had a Re-Bulk setting but I think it did ? > > The MX did not have a logic input for turning it on and off of course. OB > had a communications > device that converted their communications protocol to Modbus or Ethernet I > think it was which > may (or may not) be able to make it work. > > Could always buy something newer and keep the MX60 as a spare. > > boB > > > > On 12/1/2021 9:10 AM, frenergy wrote: >> boB, >> >> Interesting...Sounds like this is not a candidate for L-ion >> batteries. >> >> Bill >> >> On 11/30/2021 10:47 PM, b...@midnitesolar.com <mailto:b...@midnitesolar.com> >> wrote: >>> >>> Hi Bill.... >>> >>> As I remember, the min is of course... Minimum time in Absorb. >>> >>> Max is maximum time in absorb but depended on how long it took to get from >>> Bulk MPPT to that Absorb voltage. >>> >>> So if it took 3 hours to get to Absorb that morning and you had t set for >>> Max 2 hours, it would Absorb for 2 hours. >>> >>> If it only took 1 and 1/2 hours to reach Absorb voltage, the MX60 would >>> Absorb for 1 and 1/2 hours. >>> >>> It worked "OK" but these days I would probably just set it for min of some >>> 2 or 3 hours and then a max could be the same >>> time or longer for FLA batteries. >>> >>> boB >>> >>> >>> >>> On 11/30/2021 7:16 PM, frenergy wrote: >>>> Yes, the old one, not the FM. This oldie had an interesting way to set >>>> the absorption time. You would set the "min" time (in minutes) and you >>>> would set the "max" time (in hours, you have to set it to 1,2,3 or 4 >>>> hours). >>>> >>>> I need to know if I set the "min" to 10 minutes and the "max" >>>> time to one hour or two or three or four, how long will it stay in absorb? >>>> >>>> I called Outback and Megan there didn't know how this old fart >>>> works, apparently tech support isn't supporting us their old relics. >>>> >>>> Bill >>>> >>>> Feather River Solar Electric >>>> Bill Battagin, Owner >>>> 4291 Nelson St. >>>> Taylorsville, CA 95983 >>>> 530.284.7849 >>>> CA Lic 874049 >>>> solar powered since 1982 >>>> >>>> >> >> >> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient&utm_term=icon> >> Virus-free. www.avast.com >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient&utm_term=link> >> <x-msg://68/#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > _______________________________________________ > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > <http://re-wrenches.org/> > > List Address: RE-wrenches@lists.re-wrenches.org > <mailto:RE-wrenches@lists.re-wrenches.org> > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> > > There are two list archives for searching. 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