When you turn the key to start your tractor or pickup, you expect the engine to
roar to life. If it roars, that's a plus. If the battery can't start the
vehicle, that's a minus. Dead battery syndrome can ruin a good day.
To put that day off, simply maintain your battery. The battery's main and most
demanding job is starting the vehicle. The battery also supplies current when
the demand of the vehicle exceeds the output of the charging system. Since
current demands are constantly changing due to lights, air conditioning, fans
and more, the battery is always there in a standby role.
Stabilization of the voltage in the system during operation is another important
role. The battery, alternator and regulator work as a team to keep the battery
charged and the voltage stable.
How a battery charges and discharges is unique. It produces current by a
chemical reaction, and this chemical reaction also discharges it. Charging a
battery simply reverses the chemical action.
Charging is usually as simple as hooking the red lead from the charger to the
positive post and the black lead to the negative post or a good ground. But it's
not always that simple.
Equipment on the farm may have multiple batteries that can be connected in
series. For example, a late-model John Deere 4020 can use two 6-volt batteries
to produce about 12 volts.
Or, batteries may work in parallel. This is where two 12-volt batteries still
make about 12 volts. You'll find this arrangement in your diesel pickup or
larger-model tractors.
If your system is a 12-volt negative ground with two 6-volt batteries, your
batteries are in series. You can charge both batteries at the same time by
placing the red charger cable on the starter solenoid where the positive cable
is attached or the positive post's cable goes to the starter.
E X T R A: Want to know more? CLICK HERE to download this illustration of typical battery charger connections.
Connect the ground to a place away from the battery to avoid sparks. Many
manufacturers use a big nut to secure the cable for charging and jump-start
ease.
This is important: You can successfully charge (with the charger set on 12
volts) both batteries in series at the same time, but only if both 6-volt
batteries are within 0.1 volts of each other. Otherwise, the batteries must be
charged individually.
Batteries connected in parallel use the voltage of the batteries together to
produce the average voltage of the batteries.
Diesel trucks' and many late-model larger tractors' batteries can be charged
together without disconnecting them, but only when the battery voltage is above
12 volts.
Follow the same procedure described above in series charging. If batteries are
not above 12 volts, they should be disconnected from one another.
Be careful when charging batteries. Make sure you know the polarity and voltage
of the system. Many older tractors came from the factory as positive ground
systems.
But it was later thought that this polarity caused more frame rust. So the
manufacturers changed to negative ground, which is the polarity that an
alternator understands.
Many older systems that were originally positive ground systems (6- and 12-volt)
changed to negative ground systems when the tractor was converted from a
generator to an alternator.
An alternator, unlike a generator, will charge no matter which way it is
turning, but it does not like to charge unless the system is negative ground.
When you install a new battery and the alternator won't charge it, check to make
sure you installed the battery as negative ground.
See next page for tips on working around batteries.
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Here are tips for working around batteries:
- Always wear safety goggles and rubber gloves when charging a battery.
- Keep sparks and flames away from the charging area, as the battery generates
harmful fumes and explosive gas and can blow up. If you have ever seen a battery
blow up, you'll never forget it—and you may never see it again if the acid gets
in your eyes.
- To avoid sparks when removing a battery, disconnect the ground cable first.
When installing the battery, connect the ground cable last. Remember, it is
possible in old tractors for the cable leading from the positive post to be the
ground cable.
- Overcharging and undercharging are enemies of battery life. Repeated cycling
(discharging and charging) will shorten battery life.
Dirt, heat, cold and vibration are all enemies of the battery. Here are some
ways to control them:
- The one element that shortens battery life more than any other is an unsecured
battery. Under the rigors of fieldwork a loose battery likely will sustain
external and internal damage. Make sure the battery is secured in its place.
- Make sure the battery cables are connected firmly to the terminals.
- Protect the battery from engine heat.
- Top off the battery cells with distilled or soft water. Do not overfill them,
especially in warm weather.
- Keep the battery and its cables clean. Battery cable cleaner is available at
farm-supply or auto stores. You can also clean the corrosion with a mix of
baking soda and water (2 tablespoons of baking soda per pint of water).
- To ward off corrosion, try these preventive maintenance steps:
1) Put a bead
of silicon sealer at the base of each post
2) put a felt washer over the
sealer
3) cover the washer with petroleum jelly
4) attach the battery cable
5) cover the exposed areas of the battery cables with grease.
More Information
If you have questions about batteries and battery maintenance you can write our
Ask the Mechanic expert. Contact Steve Thompson at The Progressive Farmer:
Ask the Mechanic
2204 Lakeshore Drive, Suite 415
Birmingham, AL 35209 or
e-mail him at mechanic@progressivefarmer.com.