[TenTec] emergency back up power

[Eric F. Richards]

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