This could be of some interest .................................. i
purchased my 87 Vanagon used back in 1993.  I've never had to replace the
battery in this vehicle for as long as i've had it.  That makes the battery
almost 9 years old !  Never a problem so far.  Oddly enough i live just
outside of Kelowna, B.C............................which happens to be
approx 200 km (120 miles) from Hope.  hmmmmmmmmmmmmmmmmmmmmm

87  Vanagon  GL   7 Passenger
90   Jetta  TD
----- Original Message -----
From: "Joel Walker" <jwalker17@EARTHLINK.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, March 14, 2002 9:45 PM
Subject: FYI: Battery Life

> from the April 2002 issue of Road & Track
> (names of the automobiles have been changed to protect the innocent).
> ;)
>
> Question to Technical Correspondence, edited by Tom Wilson:
>
> Battery Life
> What determines battery life? I own a '91 * with over 250,000 miles on
> it and the original battery still seems strong. Obviously i do a lot
> of highway driving but even when I have been away for three or four
> weeks, upon my return the car fires right up.
>
> I also have a vacation trailer with an expensive heavy-duty deep-cycle
> battery, but it seems to last only three or four years at most. My
> small * battery is such a surprise to me that I am now afraid to even
> look at it in case I jinx it and it dies. What would make one battery
> last so much longer than another??
> Reader in Hope, BC, Canada.
>
>
> Answer from R&T:
> Well, congratulations on a decade of service from an automotive
> battery! Your experience far outstrips the normal three-to-four year
> battery life span.
>
> There is no single factor in determining battery life, although
> battery manufacturers say three years is normal, five years is
> exceptionally good and eight to 18 months is a sign that something is
> wrong. It seems these figures hold true for any quality battery, no
> matter what the warranty says. Many battery warranties are 100 percent
> up to three years, then prorated from there, which ought to tell us
> something.
>
> Anyway, from a design and manufacturing perspective the number and
> thickness of the plates, the amount of space available for the
> electrolyte between the plates, the acidity of the electrolyte and
> certainly the use of either antimony or calcium in the lead alloy
> affect battery longevity. Of these, the advent of calcium-based grids
> for premium maintenance-free batteries in the mid-1970s has  been the
> greatest boon to long-lived batteries. This is because calcium
> batteries don't gas as much as antimony-based units, helping to
> maintain a more constant electrolyte pH and keeping the plates covered
> in liquid. Excessive acidity or dried plates from gassing hastens
> plate failure.
>
> Smaller batteries with high cold-cranking amps capacity are also not
> endurance hall of fame candidates, especially in hot climates. Such
> batteries rely on large surface areas from numerous, thin plates to
> have a ready supply of active material on hand. This increases
> cranking capacity, but the thin plates succumb more quickly from
> electrolyte corrosion.
>
> Your deep-cycle RV battery should last longer than the typical
> automotive battery because it trades many thin plates for relatively
> fewer, thicker plates that better withstand deep discharges. To make
> up for their lack of electrical punch, such batteries are typically
> larger to accomodate more of their bulky plates.
>
> While likely not a factor in your *'s supernatural life span, plate
> separator design can still play a part in the short life spans of less
> expensive batteries. The bargain specials might use a cellulose-based
> plate separator fitted directly between the plates. These so-called
> leaf separators corrode away, consigning that battery to the recycle
> heap. Most modern auto batteries use superior envelope separators,
> which hold the plates via pockets molded into the case.
>
> Then there are environmental factors. Batteries prefer an even state
> of charge, minimal gassing, and cool electrolyte temperatures if they
> are to make it four years.  An overeager charging system or simply hot
> southern summer temperatures boil away the electrolyte --- there's our
> gassing problem again --- while a weak charging system can lead to a
> big discharge. Interestingly, because overcharging most quickly kills
> batteries, typically alternators are regulated to provide relatively
> low charging rates. This may mean a chronically undercharged battery
> following a jump start after the headlights were left on overnight.
> The jump gets the car going, and the alternator can charge the battery
> back to usefulness, but often not to a truly full charge.  Shortened
> battery life follows due to sulfation and crystallization when
> undercharged. This is a typical problem with deep-cycle batteries
> because of their duty cycles, but is a battery killer whenever
> undercharging is found. Interstate says battery deterioration is rapid
> whenever the battery is below 75 percent state of charge (12.45 volts
> on a digital meter or electrolyte specific gravity of 1.225), and that
> batteries should be kept at 100-percent charge at all times for
> maximum life.
>
> Corroded terminals and cable ends aid electrical leakage and hinder
> charging, also leading to chronically "low" batteries. Obviously this
> is a major contributor to short battery life.
>
> Naturally, plain old use wears out a battery. The more a battery is
> cycled, the more active material is loosened and sheds off the
> positive plate. Nearly all is restored by charging, but not 100
> percent, and so after five to six years, there is little left to give
> on the positive grid and the battery dies. However, at the same time
> negative material is shrinking away from its grid and so the typical
> three-to-four year life span. It's the negative material falling off
> its plates that causes the more gradual decline in cranking power, by
> the way. It's why an older battery can work the lights and radio,
> soldier on through summer, only to fall dead the first cold day of
> winter.
>
> So, while the variables are seemingly endless, we'll say your driving
> cycle is probably optimum for your battery and charging system. In
> other words, your standard drive is long enough to fully recharge the
> battery after the drain of starting the engine, but not too long to
> pose a threat of overcharging. Don't underestimate your cool British
> Columbia climate, either. We consulted both Douglas and Interstate
> Battery, and both were adamant that no matter what, put your * in
> Phoenix and your  battery would never have made it half as long. So,
> with a minium of hot days, attention to battery terminal cleanliness,
> a well-regulated charging system, and a maintenance-free battery, you
> have proven 10 years' worth of battery life is not impossible. If only
> the rest of us could come close!
>
> *********************