[TenTec] emergency back up power

Mon Mar 5 22:34:26 EST 2007

Well you've been lucky on the batteries.  Congrats !  :)

Stepped sine inverters are to be avoided at all costs, but in the renewable
energy world they have all but become obsolete.  You have to go out of your
way to find one any more.

My 4 kw Inverter is a small box that mounts on 4 screws.  You could put it
in a metal box if you wanted.  It weighs about 20 pounds as I recall.

PV panels are expensive, but a good investment for sure.

Yes, you need big wires for sure.  As you probably know, solar PV systems
now operate at up to 170 volts DC or so just to avoid those losses. A few
select designs go even higher. The inverter is designed to handle this.  It
makes perfect sine wave power as well.

The older 12 volt inverters are obsolete and you will find very few of them
offered any more, outside of salvage or distressed sales of old stock.

Regards,

Gary

----- Original Message ----- 
From: "Eric F. Richards" <efricha at dim.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Monday, March 05, 2007 8:38 PM
Subject: Re: [TenTec] emergency back up power

> At 05:19 PM 3/5/2007 -0500, you wrote:
> >You will find "good" used batteries sometimes, in some places.  If you
do,
> >they can save money.  If they turn out not to be so good, they will be a
> >total waste of money.  Your mileage will vary.
>
> Well, what can I say?  So far my milage has been pretty good. :-)
>
> I sank the most money into the PV panels and inverter.  There are
so-called
> "sine wave" inverters that put out a nasty stepped waveform and are quite
> destructive.  The three inverters I have all put out a perfect sine wave
> when measured on a 'scope.
>
>
>
> >I believe in using properly designed, new, deep discharge batteries.  And
> >mine do get deep discharged in an emergency, cause after all, well....its
an
> >emergency and you have to do as much as you can for as long as you can.
> >
> >It is true that certain battery designs do not require (and must not be
> >given) an equalization charge.  Consult your (new) battery supplier.
> >
> >Charging with solar power is a great idea.
> >
> >Sine wave converters greater than one kw do not require, in general, rack
> >mounts.  Maybe a couple of them do.  Most just wall mount on 4 screws.
You
> >can put them in a simple wall mount metal box if you want to.
>
> Mine sits quietly on the floor and weighs less than 10 pounds.  But once
> you go above 2 kVA -- at least with Exeltech -- you are in a whole
> different ball game in terms of what you are buying.  Below that their
> inverters are lightweight and tiny, yes.
>
>
> >Safety ground and fuse the hell out of everything.  Use DC rated fuses
where
> >appropriate.
>
> Yup.  Class T fuses are rated for 20 kA DC interruption.  DON'T skimp on
> the disconnects or the fuses.
>
> (Or, for that matter, the wires -- two-aught or bigger is what you should
> be thinking in terms of... Ohm's Law should scare you when you start
> thinking of a 2000-3000 W DC load at 24 (or 48) volts.  Choose your wire
> accordingly)
>
> Regards,
>
> Eric F. Richards, KB0YDN
>
> >Regards,
> >
> >Gary
> >
> >
> >----- Original Message -----
> >From: "Eric F. Richards" <efricha at dim.com>
> >To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> >Sent: Monday, March 05, 2007 4:44 AM
> >Subject: Re: [TenTec] emergency back up power
> >
> >
> > > At 12:20 AM 3/5/2007 -0500, Gary Hoffman wrote:
> > > >Paul,
> > > >
> > > >My array of batteries can provide about 1500 amp hours, provided that
the
> > > >discharge rate is kept reasonable.
> > > >
> > > >No discount sources that I know of.  That's because most batteries
that
> >have
> > > >seen use have been handled so poorly that they have been
significantly
> > > >impaired.
> > >
> > > May I throw in a contrary opinion?
> > >
> > > I'm running on 800 AH (24 VDC) of hospital pulls.  They saw one year
of
> > > service and were yanked.  80 AH gel-cells.
> > >
> > > The inverter is an Exeltech XP-1100 (1.1 kVA) -- too small for a
> > > legal-limit amp, but a fine sine wave inverter with less than 2% THD.
A
> > > battery balancer lets me pull 12 volts directly for the various radios
> >that
> > > use it.  A West Mountain Radio RigRunner distributes the 12 V through
> > > Anderson PowerPoles.
> > >
> > > It goes without saying that I fuse the crap out of everything.  The
> > > inverter has a separate 200 A Class-T fuse.
> > >
> > > The XP series from Exeltech is their "low cost" inverter line, and the
> >1100
> > > is as big as that series gets.  If you want more power, you need a
rack
> > > mount module with 1 kVA modules stacked with controllers,  with the
option
> > > of redundant power, etc.... and the cost goes sky high.
> > >
> > > ...oh, those batteries?  Well, they're getting old.  I've gotten
almost 10
> > > years out of them, and need to replace them.   But then, they only
have
> > > done two deep/complete discharge cycles.  I'll have no problem with
using
> > > hospital pulls or NOS again.
> > >
> > > For those still reading, the charging system is 400 W of solar panels
> > > through a PWM charger with sense lines and temperature compensation.
> >About
> > > $100 back in the day, and there are much better ones out there today.
> > >
> > >
> > > >Special electronics are not especially hard to work up yourself.  You
> >must
> > > >avoid over or undercharge, which is pretty much a matter of voltage
> > > >regulation.  And every so often you must apply an equalizing charge
to
> >make
> > > >sure that all batteries are properly topped up.  You can Google that
> >phrase
> > > >and come up with lots of stuff.  Or look at Home Power Magazine.
> > >
> > > That's fine for wet-cells, but I prefer the safety of gel cells at the
> >cost
> > > of energy density and $$$.  I'd go with a commercial circuit if you
> >haven't
> > > done a charge circuit before.  (You only equalize a gel-cell once, and
> >then
> > > you throw it away. :-))
> > >
> > >
> > >
> > > >Overspend on the batteries and make savings elsewhere if you can.
> > >
> > > Again, I think you can get away with certain things with the
> > > batteries.  New-old stock is fine, as long as they aren't more than 18
> > > months old, as are hospital pulls.  Wet cell types that have never
seen
> > > electrolyte should be fine as long as they weren't physically damaged
> > > (dropped, etc.).  However, UPS pulls from non-life-critical systems
aren't
> > > worth it.  Pulls from repeater sites are a no-no.
> > >
> > > It helps if you know people who've been through this before in your
local
> > > area.  At local hamfests here in Colorado, there are dealers who work
in
> > > good faith and there are the rest.  Find out from someone who's been
> > > through it all before.
> > >
> > > Regards,
> > >
> > > Eric F. Richards, KB0YDN
> > >
> > > --
> > > Eric F. Richards
> > > efricha at dim.com
> > > "The weird part is that I can feel productive even when I'm doomed."
> > >   - Dilbert
> > >
> > > _______________________________________________
> > > TenTec mailing list
> > > TenTec at contesting.com
> > > http://lists.contesting.com/mailman/listinfo/tentec
> > >
> > >
> >
> >
> >_______________________________________________
> >TenTec mailing list
> >TenTec at contesting.com
> >http://lists.contesting.com/mailman/listinfo/tentec
>
> --
> Eric F. Richards
> efricha at dim.com
> "The weird part is that I can feel productive even when I'm doomed."
>   - Dilbert
>
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
>