[RE-wrenches] Programmable Battery Charger

Tue Dec 16 11:11:21 PST 2014

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

On 12/16/2014 6:39 AM, Larry wrote:
> 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?
>
> 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.
> Thank you,
>
> Larry
> On 12/15/14 6:51 PM, jay peltz wrote:
>> Hi Kirk,
>>
>> If you use a 200vdc midnight CC you'll have no issues.
>> When you rectify 120vac its up around 166vdc
>> ( uses the peak vac which is around 170vac.)
>>
>> 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.
>>
>> jay
>> peltz power
>> On Dec 15, 2014, at 5:38 PM, Kirk Herander wrote:
>>
>>> 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.
>>> *Kirk Herander*
>>> *VT Solar, LLC*
>>> */Proven PV provider since 1991/*
>>> *www.vermontsolarnow.com*
>>> dba Vermont Solar Engineering
>>> NABCEP^TMInaugural Certificant
>>> VT RE Incentive Program Partner
>>> 802.863.1202
>>> *From:*RE-wrenches 
>>> [mailto:re-wrenches-bounces at lists.re-wrenches.org]*On Behalf Of*Dan 
>>> Tittmann
>>> *Sent:*Monday, December 15, 2014 8:18 PM
>>> *To:*info at windsine.org <mailto:info at windsine.org>; RE-wrenches
>>> *Subject:*Re: [RE-wrenches] Programmable Battery Charger
>>> You can manually adjust Iotas with tweaking the potentiomiters while 
>>> monitoring it with a god volt meter. But no time adjustment.
>>> Daniel
>>>
>>> Daniel Tittmann
>>> CTO
>>> Greenwired
>>> www.greenwired.com <http://www.greenwired.com>
>>> daniel at greenwired.com <mailto:daniel at greenwired.com>
>>> 707-923-2001 (office)
>>> 707-206-5088 (Cell)
>>> On Mon, Dec 15, 2014 at 4:21 PM, Windsine Inc. <windsine at gmail.com 
>>> <mailto:windsine at gmail.com>> wrote:
>>>
>>> Check out Argus Technologies.
>>>
>>> RoyR
>>>
>>> On Dec 15, 2014 4:01 PM, "Larry" <larry at starlightsolar.com 
>>> <mailto: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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