<div dir="ltr"><div>Ray is 100% correct in regards to the fine LFP open loop setting.</div><div><br></div>The MNP series of batteries have the recommended voltages for charging on the specification sheet and the batteries. But Absorb and float setting vastly change with the system design, it depends on the size of the arrays and the generators. <div><br></div><div>I'm sure MNP can do a better job at posting some "default" open loop settings but they will not be correct for all systems. I have found that when using Fortress and Discover LFP batteries the float and bulk / absorb settings were never correct and in the end each system needed its own settings.</div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Mon, Jan 26, 2026 at 1:35 PM Ray Walters via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><u></u>
<div>
<p>No, and the settings on the side of the battery did not include
recommended absorption time. I like the "cheat sheets" provided
by Fortress and Simpliphi for use with their batteries with
various brands of controllers and inverters. However, I've since
started adjusting those substantially for off grid. I found for
Fortress for instance, that the generator needed to be started at
a higher voltage than recommended, and I set the charge voltage on
the inverters lower, because the generator was running all day
trying to fully charge the batteries. Offgrid, the goal is to get
the generator going before any possible shutdowns, run the genny
to get the batteries up to maybe 60% or 70%, and then let solar
take over again. </p>
<p>While open loop coms prevents some of the weird glitch shutdowns
that might happen with closed loop charging, using voltage
controls with LFP batteries is tricky, since the voltage is so
stable until the bottom 20% SOC of the battery. Below 20% SOC,
the voltage seems to drop like a stone, and triggering gen start
and LVD is really dependent on the loads. I'm still experiencing
catastrophic battery shutdowns, that require a trip out for manual
reset, and/or dark start. I might get usable settings for one
combination (Victron: HomeGrid, ie.) but then I need something
different for Outback: Fortress combination......I don't mind
figuring this out (actually becoming an expert) but the drive
times are killing my bottom line (and my bottom).</p>
<p>Ray Walters<br>
Remote Solar</p>
<div>On 1/25/2026 2:55 PM, Jay via
RE-wrenches wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Did they offer up any reason why there are no
charging or other programming specs online? </div>
<div dir="ltr"><br>
</div>
<div dir="ltr">Curious. </div>
<div dir="ltr"><br>
</div>
<div dir="ltr"><br>
</div>
<div dir="ltr"><br>
</div>
<div dir="ltr"><br>
</div>
<div dir="ltr"><br>
</div>
<div dir="ltr"><br>
</div>
<div dir="ltr"><br>
<blockquote type="cite">On Jan 25, 2026, at 12:56 PM, Ray
Walters via RE-wrenches
<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank"><re-wrenches@lists.re-wrenches.org></a> wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">
<p>Its really hard to find charge settings for Midnite
Powerflow, but Midnite tech support told me the #s are
printed on the side of the battery. Definitely not 57.6v,
which sounds way too high.</p>
<p>Charge : 56.16 vdc<br>
Float: 54 vdc</p>
<div>On 1/25/2026 11:20 AM, William
Bryce via RE-wrenches wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">This is more of a programming / battery issue
than an inverter inverter. In looking at the system
settings, you are pushing the voltages of LFP to the max.
This will cause the BMS to protect the battery. The
"Spikes are caused by the BMS operation not the inverter
(the current has to go someplace), the BMS FET's open
under load the voltage will spike. The BMS should be the
last resort in regards to battery charging protection.
<div><br>
</div>
<div>All LFP batteries (cells) are mostly the same, and
are made by 5 companies. The upper and lower voltages
are set for LFP cell makers. The battery (pack) builders
then program the BMS, and post on specification sheets
the recommended setting voltages. With <u>lower quality
cells and lower warranties</u>, you will see the
voltages are set <u>higher.</u> When using A+ cells and
long warranties you will see<u> lower</u> top voltage
settings.<br>
<div><br>
</div>
<div>Here are the recommended voltages for a 48V LFP
(16S) pack when using A+ cells from CATL, BYD, and EVE
(this is from the cell manufacturers recommendations)</div>
<div><strong style="color:rgb(0,0,0)"><br>
</strong></div>
<div><strong style="color:rgb(0,0,0)">Charging range:</strong><span style="color:rgb(0,0,0)"> </span><strong style="color:rgb(0,0,0)">~52 V to 56 V</strong><br>
</div>
<div>
<ul><li style="color:rgb(0,0,0)">
<p><strong>Full resting:</strong><span> </span><strong>~54.6
V</strong></p>
</li>
<li style="color:rgb(0,0,0)">
<p><strong>Nominal operation:</strong><span> </span><strong>~51–53
V</strong></p>
</li>
<li style="color:rgb(0,0,0)">
<p><strong>Stop discharging (resting):</strong><span> </span><strong>~48
V</strong></p>
<p><strong>Recommended MAX voltage is 56.8V (for
normal use) 58.2 </strong><strong>Absolute MAX
(chemistry limit) Cell damage</strong></p>
</li></ul>
</div>
<div>You need to update the MNP AIO system firmware to
V7. It is now the only AIO that has true charging
control for LA (that works) the changes made were
recommended by a highly qualified LA battery rep who
is also a part of this list. Set the absorb setting
as you need, but be aware that it does not start the
adsorb until the current drops below ~ 10 amps or so.</div>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sun, Jan 25, 2026 at
12:48 PM Zeke Yewdall via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div>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.</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>Zeke</div>
<div><br>
</div>
</div>
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