<VV> Battery Tender

[John]

A modern battery charger is a much better product than those in the
heyday of the Corvair.  When a automotive lead acid type battery is
improperly charged or allowed to self discharge, as occurs during
non-use, sulphate crystals build up on the battery's plates. The
sulphate prevents the battery from being fully charged and therefore it
is unable to deliver its full capacity. When trying to charge a battery
in this state it only gets hot and looses water, the specific gravity of
the electrolyte is not increased to its normal full charge state. The
only thing you do is kill the battery completely.

If a battery has a resting voltage of at least 1.8 Volts/cell and no
cells are shorted, desulphation of its plates can be done. The object is
to get the cell voltage high enough for the sulphate to dissolve without
boiling or melting the battery. This is achieved by applying higher
voltage (pulses) for shorter periods and then let the battery rest for a
while. All of this is controlled by a microprocessor while measuring the
battery terminal voltage during the rest period.  When the terminal
voltage reaches nominal voltage the charger automatically stops the
pulses and changes to a tapered charge mode.  This restores the battery
to full capacity.  The microprocessor keeps track of the amp hours put
into the battery and when it reaches the set point it switches to the
float charge mode.

I own several of these type chargers.  By far the best of the consumer
grade products is the Schumacker Model SS-120A-PE, Ship'n Shore 12 amp
Battery Charger/Maintainer.  Look for it at Farm Supply stores or Marine
(Boat) Supply stores.  I paid $49 three years ago for my first unit and
$52 two months ago for a second one.  Stay away from those that have an
internal cooling fan, sold by Wal Mart and FLAPS.  The cooling fan does
not hold up in the dirty garage environment; it's only a cheap computer
type plastic bearing type fan.  The Schumacker has no fan and uses an
old fashion iron core transformer.  Much better.

Check the product at: <http://www.batterychargers.com/>  On line buying
price is $70.

John (no door bell diode charger) Dozsa


> From: UltraMonzaWest@aol.com
> Date: Thu, 3 Jun 2004 16:08:27 EDT
> Subject: Re: <VV> Battery Tender
> To: virtualvairs@corvair.org
> 
> For those of you not familiar with these devices, these are not the
> same as a simple battery charger that keeps on charging. These shut off
> and monitor the charge. They are designed, not so much to charge a dead
> battery, but to maintain one. They seem to be ideal for maintaining
> batteries that are seldom used. They are not cheap; mine was $49.99 at
> Northern.
> 
> Bruce
> 
> **********************************************************
> 
> Many of us cannot imagine what you're talking about! gggg
> 
> We all bought the same thing for  $1.99 ....30 yrs. ago....or made one for
> $1.14  plus labor!
> 
> A 1 amp TRICKLE charger never needs to shut off.......nor does it ever
> overcharge a battery.....
> 
> simple physics!
> 
> Reminds me of the time when Facility Eng.  wanted to spend $80k  for a
> "timebased"  Kilowatt control for a generator....they sited the antique equipment it
> would replace...complete with a remark about the "pencil" marks on the
> rheostat [ dial]...
> 
> I then produced the digital record to show  how the generator did EXACTLY
> what they wanted to do.....when the knob was set to the Pencil Mark!!!   AH!
> progress!  ggg
> 
> Matt