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A lot of misinformation is floating around out there about
batteries. This page will clear that up for you.
Most cranking batteries are lead-acid. If you have another
type, like nickel-cadmium, call us so that we can get you specific information.
A lead-acid battery is a pre-packaged chemical reaction. It is made of individual cells connected in series to achieve the appropriate voltage. Each cell produces about 2 volts. When in series you just add up the voltage of each cell. Six cells make a 12-volt cranking battery.
Each cell is made up of lead grids electrically connected together with lead dioxide pressed into the positive grids and spongy metal lead pressed into the negative grids. The grids are then immersed in a 33% solution of sulfuric acid.
Sulfuric acid is real aggressive. But it doesn’t attack the lead right away. Before the reaction can begin, an electrical circuit has to be made between the positive and negative poles. This can be the cranking motor, a lamp, or any DC electrical load.
Once the circuit is made, electrons move from the negative post to the positive post. It is the movement of these electrons, like water in a garden hose, which does the work. Electrons that flow through the windings of a motor create the magnetic field that causes the motor to turn. Electrons that flow through the filament of a lamp create the heat, as a result of friction, that causes the filament to glow.
Voltage is a measurement of electrical pressure. And just
like pressure in a garden hose, you may have good pressure until you turn
the hose on. The battery may measure good voltage until you load it. So
you always test a battery under load.
Easy Battery Test
1. Set voltmeter (VOM) to DC and connect it to your battery terminals so that you can see it from the generator control panel.
2. Disconnect or turn off the automatic battery charger.
3. Check the voltage. If it reads below 12 volts (24 volts if it as a 24 volt system) the battery is either bad or discharged. If it reads between 12 VDC and 13.5 VDC (24 volts to 27 volts for a 24-volt system) go on to step 4.
Caution:
If the battery reads above 13.5 volts (27 volts for a 24 volt system) call us. It may be overcharged. An overcharged battery can explode!
4. Remove the B+ connection from the ignition coil if the engine is gas fired or remove the B+ connection from the fuel cutoff valve if the engine is diesel. The idea here is to disable the engine so that it won’t start.
5. Stand well away from the battery (See our caution above!!!) and crank the engine for 10 to 15 seconds.
If the battery is good the voltage will stay above 9 volts
(18 volts if it is a 24-volt system)
Other important stuff
1. Batteries don’t go dead because you put them on a concrete floor. It only seems that way.
2. Battery terminals have to remain clean. Corrosion will prevent the battery from accepting a charge and cause premature failure.
3. Add only pure distilled water. Additives can’t help. They only seem to.
4. Batteries are like eggs. You want them fresh. Remember that a battery is a pre-packaged chemical reaction. All lead-acid batteries begin to lose capacity the minute they leave the factory. After about three years, all cranking batteries for emergency generator use should be replaced. You may use it in a tractor or old pickup truck, but it is no longer fit for emergency use.
5. Always re-charge a battery immediately after use. If
you don’t do this, the lead sulfate that builds up on the positive plates
as a natural part of the discharge process will set up like concrete and
refuse to allow a complete recharge. This is what is meant when they say
the battery has sulfated. This also is the reason you may see "positive
terminal growth" or swollen batteries.