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<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 class="moz-cite-prefix">On 1/25/2026 11:20 AM, William Bryce
via RE-wrenches wrote:<br>
</div>
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<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
class="gmail-Apple-converted-space"
style="color:rgb(0,0,0)"> </span><strong
style="color:rgb(0,0,0)">~52 V to 56 V</strong><br>
</div>
<div>
<li style="color:rgb(0,0,0)">
<p><strong>Full resting:</strong><span
class="gmail-Apple-converted-space"> </span><strong>~54.6
V</strong></p>
</li>
<li style="color:rgb(0,0,0)">
<p><strong>Nominal operation:</strong><span
class="gmail-Apple-converted-space"> </span><strong>~51–53
V</strong></p>
</li>
<li style="color:rgb(0,0,0)">
<p><strong>Stop discharging (resting):</strong><span
class="gmail-Apple-converted-space"> </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>
</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 gmail_quote_container">
<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"
moz-do-not-send="true" class="moz-txt-link-freetext">re-wrenches@lists.re-wrenches.org</a>>
wrote:<br>
</div>
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<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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