Some battery info I've learned and found over the years. (I've worked as a
auto mechanic for 20 years and have been researching batteries for the
electric car I recently purchased. 1975 Citicar, it uses a Lucas turnsignal
switch. Yikes =8+() )
The old "don't store a battery on a concrete floor" story is not true. A
battery really doesn't know or care what it is sitting on.
A battery will self discharge over time. This is especially true of the top
is dirty and covered with acid.
A discharged battery will be damaged if it sits in this state too long. This
occurs because the sulfuric acid is absorbed into the lead plates during
discharge. Left in this state the sulfur grows crystals becoming sulfation
<sp>.
Overcharging/overheating a battery will distort plates causing failure
A battery has a finite number of charge/discharge cycles. Batteries like to
be cycled. Yes, I know, two opposing terms. If a battery sits unused ( like
for a year or more) it will deteriorate but using it will reduce it's cycle
life.
State of charge, lead acid battery in it's resting state. For this test to
be valid, the battery must be off the charger/engine not run for ~ 3 hours
or the surface charge removed my running a electrical load ( headlights for ~
4 minutes) then letting the battery rest for 15 minutes.
12.66 100%
12.45 75%
12.22 50%
12.05 25% Go lower than this and the battery will be damaged
11.70 0% Usually you can only go here once or twice before the battery
is junk
For 6V batteries divide the voltage on the chart by 2. The above chart does
not test capicity, a load tester is need for that test. Load testing
involves placing a large electrical load across the battery terminals and
watching the voltage.
Think of a battery as a gas tank for electricity. If the tank is full ( 10
gal ) and the engine uses 2 gal to start then the charging system replaces 2
gal, everything is OK. As the battery wears out the capacity becomes lower
9, 8, 7, 6,. . .Gal. When the battery has 3 gal capacity starting is still
ok, at 2 gal things are becoming edgy. At 1.8 gal the car runs out of
electricity, click, click. .. .
For max power a battery must be ~ 70*F , higher than that water tends to
evaporate.
For storage, batteries like cold temps. 40*F would be great since self
discharge is reduced at low temps. Storage at 32*F or lower will freeze the
electrolyte _IF_ the state of charge is low.
Engines need more power to crank in cold weather, a battery puts out less
power ( amps ) in cold weather. A weak battery might perform fine in summer
but be "dead" in winter. If this is the case, the battery is pretty much
worn out. I do keep a few of these around for testing and car moving.
Normally I don't do anything special to batteries for short term storage ( 3
months). An occasional voltage check, battery shake/tilt and charge with a
regular charger if the storage is longer.
The best battery I've found is DELCO. I've had a few that went 10 years
before failure. Since the top is sealed, corrosion caused by acid fumes is
not a problem ever ( Unless the battery is overcharged). Interstate is
second only due to slight acid leakage caused by removable caps. Exide and
low line store brand batteries tend spray acid fumes making a real mess.
Harold
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