battery backup project
gandrews at ntplx.net
Mon Dec 14 22:30:49 EST 2009
Not a problem. I still push the envelope. Tried recharging a rechargeable
Lithium Ion battery in the last year. Got a little over confident in my
understanding of the rate of change of temperature. The AA battery went
bang. I had to get out the full face gas mask to get in the room! Had to
open the window and put a big fan in the window. It took three hours or so
before the air was of breathing quality. It took several hours more to clean
up the debris. The AA battery was reduced to a large number of chunks, none
bigger than gnat size. Glad no one or the cats were in the room at the time.
It was enough to keep away from rechargeable LiIon batteries! I was finding
pieces of the battery for six months afterwards.
----- Original Message -----
From: <n1ujs at toast.net>
To: <450 at lists.vhfwiki.com>
Sent: Monday, December 14, 2009 6:34 PM
Subject: Re:  battery backup project
> Thanks for your input George. Always good to hear
> from a man of science. I tend to be more reckless in
> my "mad scientist" endeavors of course, but will take
> your warnings under advisement!
> ------- Original Message -------
> From : George Andrews[mailto:gandrews at ntplx.net]
> Sent : 12/13/2009 12:25:30 PM
> To : 450 at lists.vhfwiki.com
> Cc :
> Subject : RE: Re:  battery backup project
> I would only trickle charge the batteries as a
> routine (100 mA or less) once they are brought to
> full charge. Much better is to
> charge such batteries as needed. These do not appear
> to be SLA's, so there will
> be venting. What gets vented is Hydrogen gas
> (flammable, can have an explosive
> concentration issue and over time, years, will belch
> a very tiny amount of
> dilute sulfuric acid). Hydrogen flame is invisible
> unless it is burning
> something else. I would keep such a setup out in a
> well ventillated
> garage and consider the fact that car batteries can
> explode. Hydrogen
> builds up, there is an arc inside the battery or a
> source of ignition external
> to the battery. This will splatter the sulfuric acid
> over an area and on people
> if you happen to be nearby. Then there is the
> shrapnel from the battery
> I had a battery blow up in a 64 Chevy. It was a
> Sears battery with a year or so to go on the
> warranty. I thought I was the
> victim of a car bomb (radical politics days-thought
> the Birchers got me) and my
> ears were ringing for hours afterwards. The only
> idenfifiable part of the
> battery case was th botton inch or so and some of the
> lead plates. It was
> terrible decontaminating everything under the hood!
> The inverter will be expensive and might generate
> noise on HF.
> All my stuff is 12 V, including a CFL that lights
> up the shack.
> The 130 A/hr telcom batteries at the hamfest are a
> better idea.
> You could build a Schottky diode device to trickle
> charge and automatically switch over to battery on
> power failure.
> ----- Original Message -----
> To: 144.450 Mailing List
> Sent: Sunday, December 13, 2009 11:44
> Subject:  battery backup
> Successfully revived two Orbital batteries for
> backup purposes.
> Battery specs. are here:
> The plan is to tie them together as a backup
> supply for the entire shack in conjunction with an
> inverter (anyone got one
> cheap to trade or sell?).
> Total cash outlay so far, $18.00 ("core
> value" for the two batteries). They were new, but
> on the shelf at
> work since '05.
> They seem to be good as new after charging with
> my Samlex APS 1215 (shown below, 15A cont., 20A
> surge) which will be devoted
> to keeping them charged.
> 450 mailing
> 450 at lists.vhfwiki.com
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