<font size=2 face="sans-serif">Hi:</font>
<br>
<br><font size=2 face="sans-serif">I'm enjoying learning many new ways
of looking at things and of practical solutions on this forum. In
that spirit, the only thing I would add to this discussion is that the
power factor as seen by the AC source will be very poor. In that
regard, the larger the caps, the more stable the "DC" voltage,
but the poorer the PF.</font>
<br>
<br><font size=2 face="sans-serif">This will show up as much lower charging
efficiency due to the way in which AC current is drawn by the bridge rectifier/capacitor
circuit. Here's an actual graph of how a bridge rectifier connected
to a capacitor draws AC current,</font>
<br>
<br><img src=cid:_1_0D134E540D1340A4007111DE88257DB0>
<br>
<br><font size=2 face="sans-serif">The graph is from my past life a couple
of decades ago back when I was studying. It's not a conventional
phase-shift PF problem, but rather a form factor PF problem. It shows
the current drawn by a 13" PC monitor of that era, before PF correction
was mandated for all new products. In this example the 'crest factor',
(peak current as measured versus what it could have been if the current
was drawn throughout the AC pulses, was about 4x). Depending on the
size of capacitor, it can be as high as 7x.</font>
<br>
<br><font size=2 face="sans-serif">The practical effect on the wires and
devices including the diodes and charge controller, is that a lot of heat
is generated in their power components. The source of the energy
for that heat is the AC source and in cases where the AC source is a generator
that translates to much higher fuel consumption, (in some cases over 30%
more).</font>
<br>
<br><font size=2 face="sans-serif">Out of my tests back then, I also discovered
one practical recommendation. </font>
<br>
<br><font size=2 face="sans-serif">If you are using bridge rectifiers connected
to capacitors, do not have any length of wire and in particular no loop
area in the wires between the bridge rectifier and capacitors. Having
wire/loop area introduces inductance into the circuit which behaves somewhat
like an ignition coil due to the high speed reverse recovery period of
the diodes; and this happens four times every AC cycle. Given the
right conditions the voltage spikes caused by that inductance/ignition
coil like effect will make short work of the diodes and other components
which are on the circuit.</font>
<br>
<br><font size=2 face="sans-serif">The voltage spikes wont be a problem
if the bridge rectifier is as close as possible to the capacitors, but
due to reverse recovery effect, you'll still be stressing the parts and
heating wires.</font>
<br>
<br><font size=2 face="sans-serif">In my opinion, its ok to do this, but
I wouldn't push power levels to anywhere near the limits of components
and devices.</font>
<br>
<br><font size=2 face="sans-serif">JARMO</font>
<br>
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<table width=100%>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">From:</font>
<td><font size=1 face="sans-serif">"boB@midnitesolar.com" <boB@midnitesolar.com></font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">To:</font>
<td><font size=1 face="sans-serif">RE-wrenches <re-wrenches@lists.re-wrenches.org>,
</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Date:</font>
<td><font size=1 face="sans-serif">12/16/2014 11:16 AM</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Subject:</font>
<td><font size=1 face="sans-serif">Re: [RE-wrenches] Programmable Battery
Charger</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Sent by:</font>
<td><font size=1 face="sans-serif">"RE-wrenches" <re-wrenches-bounces@lists.re-wrenches.org></font></table>
<br>
<hr noshade>
<br>
<br>
<br><font size=3><br>
Larry, Pitfalls ?<br>
The biggest pitfall I would say is if you have a VERY stiff grid.<br>
<br>
If your Voc is say, 170V DC and the CC current limits it output at say,
169 V DC,<br>
they you are going to need to add an input power resistor of a couple Ohms
to<br>
help cushion the input to be more like a PV module. A lot of times,
the grid is<br>
not nearly this bad, especially generators.<br>
<br>
Also, If you are going to do this, I would NOT use Solar mode but instead
try<br>
Hydro mode set to Manual MPP voltage. First start the MPPV at something
just<br>
less than Voc or maybe, say, 160 VDC. Then, from main STATUS screen,
you can<br>
adjust the input voltage up and down by pressing the Soft-Right or Soft-Left<br>
keys respectfully. (upper right and upper left keys). Then
you can manually get<br>
a feel for what it should be set for.<br>
<br>
The Classic 200 is the only CC of ours that I would use. The 250
would work but the<br>
200 is much more suited. I wish there were a real charger that one
could buy that was<br>
isolated, and we have never really advocated MPPT charge controllers for
this but<br>
in a pinch, they always seem to work find. Never did add a "DT"
mode (after Daryl<br>
Thayer of course), but this hydro mode seems to work OK.<br>
<br>
If you want to let it sweep but setting it to 3 minutes (or higher) that
will also work.<br>
If you do that, set the minimum input voltage. Something like 140V
or so will keep<br>
it from dropping the input voltage too low and either bogging down the
input source<br>
and the rectifier bridge (especially generators)<br>
<br>
You can also set the INPUT current limit in the LIMITS menu. This
was for hydro<br>
in particular. Either limit can help reduce Isc or bogging down issues.<br>
<br>
The other pitfall is that it is NOT galvanically isolated so you should
be very careful.<br>
We use an X240 equivalent transformer to keep the batteries going in our
burn in<br>
rack using 2 Classic 200s and it works great.<br>
<br>
Also, use a nice and strong full bridge rectifier so that it applies 120
Hz instead of<br>
60 Hz to the input. That is much easier on the input capacitors and
things and just<br>
makes it work smoother. There are input capacitors (filtering) on
most charge controllers.<br>
<br>
Again, in a pinch this seems to work but watch that input max power point
voltage to make<br>
sure it is not too high compared to the Voc. If there isn't enough
voltage spacing between<br>
the two (stiff AC source) then the control isn't going to be very smooth
and might risk<br>
letting the smoke out.<br>
<br>
What ever you do here, be very careful what you touch !<br>
<br>
boB<br>
<br>
<br>
<br>
<br>
<br>
On 12/16/2014 6:39 AM, Larry wrote:</font>
<br><font size=3>I must have missed the prior discussion about using PV
CC. The concept sounds good but how many of you have done this and are
there any pitfalls to be aware of? If I use a 20 amp bridge I should be
able to produce 80 amps @ 14.4V. For continuous operation, will I need
a large heat sink on it?<br>
<br>
How does the unfiltered full wave peak voltage affect the CC over time?
Are they (specifically Midnite) really designed to handle input waveform
like this? I like this idea, especially if I can stack the controllers.</font>
<br><tt><font size=3>Thank you,<br>
<br>
Larry </font></tt>
<br><font size=3>On 12/15/14 6:51 PM, jay peltz wrote:</font>
<br><font size=3>Hi Kirk, </font>
<br>
<br><font size=3>If you use a 200vdc midnight CC you'll have no issues.</font>
<br><font size=3>When you rectify 120vac its up around 166vdc</font>
<br><font size=3>( uses the peak vac which is around 170vac.)</font>
<br>
<br><font size=3>For a 150vdc max controller ( midnite 150) or a
144vdc ( outback FM) then a buck transformer or standard transformer is
the trick to reduce the AC and hence the DC for these lower voltage units.</font>
<br>
<br><font size=3>jay</font>
<br><font size=3>peltz power</font>
<br><font size=3>On Dec 15, 2014, at 5:38 PM, Kirk Herander wrote:</font>
<br>
<br><font size=4 color=#004080 face="Calibri">This has been discussed on
this list in years past. It is possible to use an outback charge controller
as a battery charger. You need to put the 120 AC into a bridge rectifier,
then feed the 120 DC into the controller’s PV input. So you’ll have an
80 amp battery charger.</font>
<br><font size=4 color=#004080 face="Calibri"> </font>
<br><font size=4 color=#004080 face="Calibri"><b>Kirk Herander</b></font>
<br><font size=4 color=#004080 face="Calibri"><b>VT Solar, LLC</b></font>
<br><font size=4 color=#004080 face="Calibri"><b><i>Proven PV provider
since 1991</i></b></font>
<br><a href="x-msg://519/www.vermontsolarnow.com"><font size=4 color=blue face="Calibri"><b><u>www.vermontsolarnow.com</u></b></font></a>
<br><font size=4 color=#004080 face="Calibri">dba Vermont Solar Engineering</font>
<br><font size=4 color=#004080 face="Calibri">NABCEP<sup>TM </sup>Inaugural
Certificant</font>
<br><font size=4 color=#004080 face="Calibri">VT RE Incentive Program Partner</font>
<br><font size=4 color=#004080 face="Calibri">802.863.1202</font>
<br><font size=4 color=#004080 face="Calibri"> </font>
<br><font size=2 face="Tahoma"><b>From:</b> RE-wrenches [</font><a href="mailto:re-wrenches-bounces@lists.re-wrenches.org"><font size=2 color=blue face="Tahoma"><u>mailto:re-wrenches-bounces@lists.re-wrenches.org</u></font></a><font size=2 face="Tahoma">]
<b>On Behalf Of </b>Dan Tittmann<b><br>
Sent:</b> Monday, December 15, 2014 8:18 PM<b><br>
To:</b> </font><a href=mailto:info@windsine.org><font size=2 color=blue face="Tahoma"><u>info@windsine.org</u></font></a><font size=2 face="Tahoma">;
RE-wrenches<b><br>
Subject:</b> Re: [RE-wrenches] Programmable Battery Charger</font>
<br><font size=3 face="Times New Roman"> </font>
<br><font size=3 face="Times New Roman">You can manually adjust Iotas with
tweaking the potentiomiters while monitoring it with a god volt meter.
But no time adjustment.</font>
<br><font size=3>Daniel</font>
<br><font size=3> </font>
<br>
<br><font size=3>Daniel Tittmann </font>
<br><font size=3 face="Times New Roman">CTO</font>
<br><font size=3 face="Times New Roman">Greenwired</font>
<br><a href=http://www.greenwired.com/ target=_blank><font size=3 color=blue face="Times New Roman"><u>www.greenwired.com</u></font></a>
<br><a href=mailto:daniel@greenwired.com target=_blank><font size=3 color=blue face="Times New Roman"><u>daniel@greenwired.com</u></font></a>
<br><font size=3 face="Times New Roman">707-923-2001 (office)</font>
<br><font size=3 face="Times New Roman">707-206-5088 (Cell)</font>
<br><font size=3 face="Times New Roman"> </font>
<br><font size=3>On Mon, Dec 15, 2014 at 4:21 PM, Windsine Inc. <</font><a href=mailto:windsine@gmail.com target=_blank><font size=3 color=blue><u>windsine@gmail.com</u></font></a><font size=3>>
wrote:</font>
<p><font size=3>Check out Argus Technologies.</font>
<p><font size=3>RoyR</font>
<br><font size=3 face="Times New Roman">On Dec 15, 2014 4:01 PM, "Larry"
<</font><a href=mailto:larry@starlightsolar.com target=_blank><font size=3 color=blue face="Times New Roman"><u>larry@starlightsolar.com</u></font></a><font size=3 face="Times New Roman">>
wrote:</font>
<br><font size=3 face="Times New Roman">Wrenches,<br>
<br>
Does anyone know of a 120/12 volt battery charger that can be programmed
for absorb and float voltage and time in absorb mode? I have been needing
this product for many years but I can only find it in inverters with built
in chargers from Magnum, Outback, and Xantrex.<br>
<br>
-- <br>
Thank you,<br>
<br>
Larry Crutcher<br>
Starlight Solar Power Systems</font>
<p>
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