[RE-wrenches] Programmable Battery Charger

Wed Dec 17 07:27:44 PST 2014

Larry, have you tried http://www.quickcharge.com/ 

Christopher

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
Behalf Of Larry
Sent: Wednesday, December 17, 2014 09:51
To: RE-wrenches
Subject: Re: [RE-wrenches] Programmable Battery Charger

boB and Jarmo, thanks for great explanations.......So, let's dump that idea
and go back to square one: a programmable 1.5kW charger for 12 volt
batteries. I have been checking with all the charger manufacturers I can
find and no one makes this product. Argus said no, Pro Charging said no, a
few others, no.

Brian, an inverter/charger and remote will work great but that still
represents $1000 cost and about $1350 to my customer for a 100 amp charger.
But, so far, this is my only option.

A few years ago Magnum Energy told me they were working on a stand alone
programmable charger but nothing yet. It probably does not cost much less to
build than the inverter/charger does.

Thanks to all for the answers.

Thank you,

Larry 

On 12/16/14 2:19 PM, boB at midnitesolar.com wrote:

Jarmo, you are absolutely correct.   This is another great reason  NOT to
use an MPPT charge controller
as an AC sourced battery charger.   Also, if my instructions are not
followed to a TEE, the CC WILL blow up !

The input capacitors are going to wear out MUCH sooner than a real charger
because of the 60Hz or 120
Hz ripple shown in Jarmo's graph.  Capacitor ripple abuse was one answer to
one of Larry's questions about long term
reliability.

Also, if the input diodes short, you are applying AC directly to the input
capacitors and
will go POOF as well as the power section.

And you would NOT know that you needed an input power resistor first or
possibly where
to even find one of the correct resistor values and power ratings if the
input source is stiff.
This is the scariest problem in my mind....  Too high of input max power
voltage, overcurrent
and then, battery voltage regulation will overshoot without that resistor.

I would just spend the extra money and do this right in the first place and
don't try to
cut corners on price.

Brian Teitelbaum had the best idea I think...  Just buy an inverter with a
power factor corrected
charger like the newer Schneider SW inverter/charger (I think that was the
one ?) or one of
the MSW Magnums.  Or, a decent charger if one exists.  Haven't seen the
Argus/Alpha one.

MPPT charge controllers are really just NOT designed for this.  (although
they might work for a while).

In fact, Ryan from MidNite Solar blew up several Classics at first.

But knowing that some folks are going to try this, I thought it best to give
at least some directions.

Thanks,
boB

On 12/16/2014 12:34 PM, Jarmo.Venalainen at schneider-electric.com wrote:

Hi: 

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. 

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, 

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. 

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). 

Out of my tests back then, I also discovered one practical recommendation.

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. 

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. 

In my opinion, its ok to do this, but I wouldn't push power levels to
anywhere near the limits of components and devices. 

JARMO 

____________________________________________________________________________
_________ 

Jarmo Venalainen  |   Schneider Electric   |  Solar Business  |   CANADA  |
Training & Development Specialist - Senior 
Phone: +604-422-2528  |   Fax: +604-420-1591  |   Mobile: +604-505-0291 
Email:  <mailto:jarmo.venalainen at schneider-electric.com>
jarmo.venalainen at schneider-electric.com  |   Site: <http://www.sesolar.com/>
www.SEsolar.com  |   Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 

  _____  

Larry, Pitfalls ?
The biggest pitfall I would say is if you have a VERY stiff grid.

If your Voc is say, 170V DC and the CC current limits it output at say, 169
V DC,
they you are going to need to add an input power resistor of a couple Ohms
to
help cushion the input to be more like a PV module.  A lot of times, the
grid is
not nearly this bad, especially generators.

Also, If you are going to do this, I would NOT use Solar mode but instead
try
Hydro mode set to Manual MPP voltage.  First start the MPPV at something
just
less than Voc or maybe, say, 160 VDC.  Then, from main STATUS screen, you
can
adjust the input voltage up and down by pressing the Soft-Right or Soft-Left
keys respectfully.  (upper right and upper left keys).  Then you can
manually get
a feel for what it should be set for.

The Classic 200 is the only CC of ours that I would use.  The 250 would work
but the
200 is much more suited.  I wish there were a real charger that one could
buy that was
isolated, and we have never really advocated MPPT charge controllers for
this but
in a pinch, they always seem to work find.  Never did add a "DT" mode (after
Daryl
Thayer of course), but this hydro mode seems to work OK.

If you want to let it sweep but setting it to 3 minutes (or higher) that
will also work.
If you do that, set the minimum input voltage.  Something like 140V or so
will keep
it from dropping the input voltage too low and either bogging down the input
source
and the rectifier bridge (especially generators)

You can also set the INPUT current limit in the LIMITS menu.  This was for
hydro
in particular.  Either limit can help reduce Isc or bogging down issues.

The other pitfall is that it is NOT galvanically isolated so you should be
very careful.
We use an X240 equivalent transformer to keep the batteries going in our
burn in
rack using 2 Classic 200s and it works great.

Also, use a nice and strong full bridge rectifier so that it applies 120 Hz
instead of
60 Hz to the input.  That is much easier on the input capacitors and things
and just
makes it work smoother.  There are input capacitors (filtering) on most
charge controllers.

Again, in a pinch this seems to work but watch that input max power point
voltage to make
sure it is not too high compared to the Voc.  If there isn't enough voltage
spacing between
the two (stiff AC source) then the control isn't going to be very smooth and
might risk
letting the smoke out.

What ever you do here, be very careful what you touch !

boB

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. 

On Dec 15, 2014 4:01 PM, "Larry" <larry at starlightsolar.com> wrote: 
Wrenches,

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.

-- 
Thank you,

Larry Crutcher
Starlight Solar Power Systems 

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