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Chris<br>
Yes some charge controllers regulate pretty slow. So if the battery
goes away on them they can skyrocket in voltage on there battery
side before they can catch themselves. This may only be for 2-3
seconds or so but that is all it takes to send an inverter up in
smoke. <br>
<br>
This is also the reason you here people complain of small AGM
battery banks going over voltage from time to time. These same
slower controllers will take that same 2-3 seconds to catch
themselves if a big load is turned off. <br>
<br>
Ryan<br>
<span class="moz-txt-tag">-- <br>
</span>Ryan Stankevitz
<br>
Technical Support Manager
<br>
MidNite Solar Inc.
<br>
<a class="moz-txt-link-abbreviated"
href="mailto:ryan@midnitesolar.com">ryan@midnitesolar.com</a>
<br>
360-403-7207 XT 151
<br>
Skype ID ryan.midnite
<br>
<br>
<div class="moz-cite-prefix">On 3/16/2013 10:28 AM, Chris Mason
wrote:<br>
</div>
<blockquote
cite="mid:CAG6C1qmFdnpUs5hr=GY4UCtWU9tOkWyn-Qt-VDAV5mhL3oCUdA@mail.gmail.com"
type="cite">I want to understand the issue if you don't mind. Are
you saying that an MPPT charge controller has no voltage limits? I
would have presumed a CC would know that there is no batteries
attached.
<div>From your email, you want a device that will measure the CC
output voltage, and shut it down if it exceeds a limit. For the
48V systems I normally install, that would be ...65V? </div>
<div>It would be trivial to setup an Arduino with a voltage input
to monitor the CC output voltage. The harder part would be to
turn off the CC when there was excessive voltage. Unless the CC
had an Aux input, you would need a contact rated for the DC
Current. Other than, it's very simple to do.<br>
<div>
<div><br>
<br>
<div class="gmail_quote">On Fri, Mar 15, 2013 at 11:05 PM,
Dan Fink <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:danbob88@gmail.com" target="_blank">danbob88@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
This has been happening all too frequently here. We live
in a big area<br>
of off grid homes, dozens of systems.<br>
Lost a customers Trace 2624 this morning; One L-16 in
older 24v bank<br>
opened internally. PV array/MPPT control zorched
inverter as soon as<br>
the sun came up. First indication of problems last nite
when customer<br>
hit microwave to warm up dinner and inverter went crazy.
This morning<br>
the bad battery showed 3.2v (yes, I would expect 2 or 4
also) the rest<br>
the usual 6+v. Turned on PV array, bad battery
immediately up to 11v<br>
(yes, 6v L16).<br>
<br>
Somebody needs to build a "battery condom" with big
stacked diodes on<br>
a big heat sink or some such solution. A voltage brick
wall for system<br>
charging inputs. MPPT PV controllers do NOT protect a
inverter from<br>
input overvoltage if all or part of the battery bank
disappears! And<br>
last year we saw a nice battery box fire and zorched
inverters due to<br>
similar -- dual 48v L16 strings, one cell failed and
opened, other<br>
string dumped everything into the bad one, smoke and
flames. Parallel<br>
fusing would have stopped that......but not stopped the
loss of dual<br>
stacked XW inverters from PV overvoltage.<br>
<br>
Or am I missing something here?<br>
<br>
Dan Fink,<br>
Executive Director;<br>
Otherpower<br>
Buckville Energy Consulting<br>
Buckville Publications LLC<br>
NABCEP / IREC accredited Continuing Education Providers<br>
970.672.4342<br>
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<br clear="all">
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-- <br>
Chris Mason
<div>President, Comet Systems Ltd</div>
<div><a moz-do-not-send="true"
href="http://www.cometenergysystems.com" target="_blank">www.cometenergysystems.com</a></div>
<div>Cell: 264.235.5670</div>
<div>Skype: netconcepts</div>
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