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<p>The Classic is pretty good at catching spikes but it's a
compromise in design as to how high above the present</p>
<p>battery voltage a controller can quickly respond to a real rising
battery voltage and how often it will catch an</p>
<p>extremely fast noise spike and become a nuisance.</p>
<p>Another good test is, while a charge controller is running hard,
turn off the battery breaker to the charge</p>
<p>controller itself and watch the CC terminal voltage to see how
high it rises during that instance. Before the</p>
<p>CC turns itself off that is... That would be a worse case
scenario because the battery will not be holding the</p>
<p>voltage down at all. This method was used in the design of the
Classic but I haven't tried that in a while</p>
<p>but should be pretty good.<br>
</p>
<p>Regarding the "whip" effect (or the French version of the word),
the battery impedance should help <br>
</p>
<p>to slow down the battery voltage rise time after the grid or
inverter goes away but that time will vary.</p>
<p>The Classic won't log a high voltage unless it stays for more
than like, 2 seconds or so but should catch</p>
<p>a high voltage within a second. Even if it does well, a battery
that rises fast to an overvoltage will</p>
<p>probably stay high because of the whip effect. Capacitors do
this very will too of course.</p>
<p>You could, I suppose, excess battery charge voltage back into the
PV array but we try NOT to do</p>
<p>this for various reasons. Either way, a short but not too high
of voltage spike (even 65V for 48V system)</p>
<p>should not hurt anything. <br>
</p>
<p>boB<br>
</p>
<p><br>
</p>
<br>
<div class="moz-cite-prefix">On 7/21/2017 6:48 AM, Drake wrote:<br>
</div>
<blockquote type="cite"
cite="mid:20170721134849.ECFA41055B@che.dreamhost.com">
Hello boB and Steve,<br>
<br>
I haven't been able to make it to the site yet, but so far, no
more
reports of spikes. I plan to try boB's suggestion of shutting off
the
grid input while it is selling, to see what happens. <br>
<br>
The spike did only last one second, so I don't think it is a
chemical
whip effect. If the spike only lasted a fraction of a second,
wouldn't
the Mate 3 still show the event lasting a second, since that is
its
lowest level of granularity? <br>
<br>
The array size is 2240 W and the Concorde battery bank is 305 AH
at 48 V
for a C/6.5 charge rate. The battery bank should have been fully
charged. If the grid went down and the Radian quit selling during
a heavy
selling period, could that not cause a 1 second voltage spike, or
should
the Classic catch it instantaneously? <br>
<br>
Thanks,<br>
<br>
Drake <br>
<br>
At 11:49 PM 7/18/2017, <a class="moz-txt-link-abbreviated" href="mailto:bob@midnitesolar.com">bob@midnitesolar.com</a> wrote:<br>
<br>
<br>
<blockquote type="cite" class="cite" cite="">The Classic can
overshoot but
not very much, normally.<br>
<br>
I would try this...<br>
<br>
Sell to grid while watching the battery voltage and then turn
the
inverter breaker off<br>
<br>
and see what the battery voltage does. If the battery voltage
rises
to the mid 60V range<br>
<br>
from a low sell voltage of around 52 or 53V, then something is
really
amiss.<br>
<br>
If the system has been in service for some time, you might also
check the
capacity of<br>
<br>
the batteries. They should not easily allow 65-ish volts. I
don't think that the<br>
<br>
FM's communication can respond to keep spikes from happening
any
better<br>
<br>
than it could without communications. Data packets just don't
come
all that<br>
<br>
often.<br>
<br>
boB<br>
<br>
On 7/18/2017 5:25 PM, Jerry Shafer wrote:<br>
<blockquote type="cite" class="cite" cite="">Wrenches <br>
The Outback system with grid connection would be programmed
for grid
connection all the way from the inverter to the Outback FM CC,
using a
midnite CC this option may not be possible resulting to a CC
push if the
grid disconnects resulting in a spike. the disconnect might be
from
settings to tight or as it was said utility spikes. You might
thing that
the battery bank should take it up but internal resistance in
the battery
or to it may prevent it. The other thing I would look at is
connections,
if there is any resistance in a connection this could happen.
<br>
<br>
On Mon, Jul 17, 2017 at 2:36 AM, Drake
<<a href="mailto:drake.chamberlin@redwoodalliance.org"
moz-do-not-send="true">
drake.chamberlin@redwoodalliance.org</a>> wrote:<br>
<dl>
<dd>Hello Wrenches,<br>
<br>
</dd>
<dd>My client reported seeing an overvoltage error message
on her Mate 3
on a Radian system. The Radian is selling to the grid and
is being fed by
a Midnite Classic 200. It has shown two spikes so far, the
last one going
to 67 volts and lasting 1 second. The batteries are
Concorde AGM, 305
AH.<br>
<br>
</dd>
<dd>Does this momentary spike seem like a problem or a
warning of
problems to come?<br>
<br>
</dd>
<dd>Thanks,<br>
<br>
</dd>
<dd>Drake<br>
<br>
</dd>
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