[TenTec] emergency back up power

[Gary Hoffman]

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.

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.

Safety ground and fuse the hell out of everything.  Use DC rated fuses where
appropriate.

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
>
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