Batteries for DeLoreans (long as usual)

["Walter" <Whalt@xxxx>]

I bought my last traditional lead acid car battery. I'm using the Optima
style from now on especially considering the extra bumpy ride my DeLorean
gives the battery.

To settle the shock & vibration debate concerning the life of a battery in a
DeLorean, here is my explanation:

The most common modes of failure in a lead acid car battery in the order
they are designed to happen are as follows:

1) Enough ash flakes off of the plates and settles in the reservoir in the
bottom filling it up to the point where it touches the bottom of the plates
shorting them out. This usually starts off as an intermittent short to one
cell weakening the battery enough to give warning that it should be replaced
soon.
2) The plates 'wear' thin enough that they become brittle and break apart.
Shock and vibration play a major role in this. So, yes, I suggest making
sure the battery sits on a foam pad and is held down well. However in most
batteries, the capacity of the reservoir is purposefully made smaller than
the ability of the plates to dump sediment. This is so that the battery
goes bad with some warning (plate shorted with sediment) rather than all at
once (broken plate causing a major short). Rebuilders take advantage of
this design by washing out the sediment and adding fresh electrolyte. When
a rebuilt battery fails, it is more apt to be from a broken plate than from
shorting sediment.
3) Over and prolonged discharge of the battery causes the plates to absorb
too much electrolyte causing them to swell, buckle, break and short
together. Shock and vibration help this process along.

The two worst conditions to store a battery are:
1) In a discharged state. If your DeLorean has a high current drain, weak
alternator or is otherwise allowed to sit long enough to deplete the battery
and you allow this to happen too often, you will significantly shorten the
life of your battery. Don't think that a large battery will make up for a
weak Ducy alternator. Storing a battery partially discharged will shorten
its life accordingly.
2) In a hot environment. This is one clear advantage the DeLorean has over
most cars. The worst place in any car to store the battery is where it will
unnecessarily absorb heat. Most cars have the battery in the engine
compartment and even next to the radiator. Sometimes they are wrapped in
foam, but this doesn't help much. Some batteries are even filled with
styrofoam beads to help insulate it from heat. This doesn't help much
either and makes them very messy to rebuild.

If you want to learn more, check out the back issues of Consumer Reports.
They are very educational.