Maverick That is a really good chart!
Thanks for providing that. On Mon, Jan 26, 2026 at 11:53 AM Maverick Brown via RE-wrenches < [email protected]> wrote: > I have never believed any LFP battery maker that has 58.4V for charge > voltage. That’s 3.65 Volts per cell in a 16S configuration. If you have any > cell imbalance inside the pack, one cell could go above the upper limit of > 3.65Vpc. > > I have installed serval brands of LFP batteries, some great brands and > some not as great. > > In pretty much all cases, I used 3.45Vpc (55.2V) as the Absorb and then > set other voltages as appropriate based on that. In several cases, I also > enabled EQ and set it to 3.5Vpc (56) just to make sure that cell balancing > has a chance. If the voltage is too low, you will see a wider battery to > battery SOC spread. I have corrected that by increasing the Absorb time > and/or bump up the ABS Voltage. > > Many battery companies have been integration guides for their battery to > Outback or Scheider. I have digested this to see what the ranges are for > open charging. It would be good to get more details about: > Cell balancing activation voltage > Method for reading the cell voltages internal to batteries (a few > companies have simple cables and easy apps for such, Pytes and Fortress) > Method for reading individual battery SOC (Pytes has a serial cable and > an app; Fortress has Guardian comm box, and there are others) > > It would be good for long term health and understanding for wrenches to > have more information… > > Here is my current working document on charging open loop. Let me know > what you would do differently. Any suggestions are appreciated. I will send > the XLS version to anyone who wants it. > > > Maverick Brown > Off-Grid Solar Commander since 2006 > *Maverick Solar Enterprises, Inc.* > * • Solar Commander Remote Power* > > * • SunFlow Systems Cathodic Protection *[email protected] > 512-460-9825 > > On Jan 25, 2026, at 3:48 PM, Jason Szumlanski via RE-wrenches < > [email protected]> wrote: > > The specs for this particular battery list a charging voltage up to 58.4V. > I believe the BMS protection level is set at 60V, but I need to confirm > with the manufacturer when they open on Monday. > > I just noticed that the AIOs responded to a relatively high load and > entered a re-bulk type of behavior. But the voltage stayed withing an > acceptable range. I'm not clear on how the AIO handles re-bulk and also why > the float voltage setpoint isn't being respected (or how absorb time is > determined). > > > Jason Szumlanski > Principal Solar Designer | Florida Solar Design Group > NABCEP Certified Solar Professional (PVIP) > Florida State Certified Solar Contractor CVC56956 > Florida Certified Electrical Contractor EC13013208 > > On Sun, Jan 25, 2026, 12:48 PM Zeke Yewdall via RE-wrenches < > [email protected]> wrote: > >> I see on the Lithionics spec sheet it says a charged voltage of 57.6 >> volts This seems very high for a 16 cell LFP battery. I am used to using >> 55 to 56 volts, maybe 56.5 volts at most on a 16 cell LFP. I suspect that >> the 57.6 is the protection voltage of the BMS, not the appropriate absorb >> voltage setting. I have seen this error a lot on lithium battery spec >> sheets, where they give the overvoltage protection level, which is not an >> appropriate absorb setting for typical solar equipment. >> >> Not everyone will agree with me, but the way I set up absorb voltages >> when doing open loop lithium battery systems is to NEVER let the BMS do >> anything. if the BMS shuts off charging, that means that I already >> failed... the charge controller or inverter should have stopped charging >> before the BMS feels the need to protect the cells. Same with low voltage >> disconnect... if the BMS shuts off due to low voltage, I already failed -- >> I should have shut the load off before the BMS felt the need to turn of >> discharge to protect the cells. The BMS is like an airbag...only to react >> in cases of emergency when the rest of the system doesn't work properly. >> >> Open loop equipment (all of the traditional outback/magnum/schneider, etc >> stuff, plus any AIO's in open loop setup) is designed to always have a >> battery in the system to stabilize the DC bus voltage. Without the >> stabilizing effect of the battery, voltage spikes can occur. I find that >> many charge controllers, especially the midnite classic and victron ones, >> can actually keep the system fairly stable without batteries, but charging >> from inverters is more questionable, and especially charging from any DC >> generators can cause severe spikes if the battery disconnects. I have fried >> equipment when a lithium battery disconnected from a large kohler DC >> generator and the generator couldn't react fast enough to keep it from >> spiking to 75 volts or more. This is why you never want the BMS to >> disconnect... which means setting absorb at a level where the BMS never >> feels threatened. Lithium battery manufactures giving the voltage at which >> the BMS disconnects as the "charge to" voltage does not help the >> situation. That may work when charging it with a dedicated lithium battery >> charger, without anything else connected to the battery while it's >> charging. But in a functioning solar system with charging from multiple >> sources and loads all occurring at the same time, we need to be smarter >> than the battery, IMO. >> >> Zeke >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> List Address: [email protected] >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> There are two list archives for searching. 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