Battery and charging system operation by sdaferv

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									Battery and Charging System

Depending on the mill model you own, your
electrical system could be quite simple or
complex. Almost all of the Wood-Mizer systems
use a 12-volt battery and alternator to meet
the many load requirements. The battery and
charging system are designed to handle these
requirements during proper operation.

The alternators on Wood-Mizer mills are larger
capacity and of higher quality than those
commonly used for automotive applications and
we use a high-output commercial battery. If
you can grasp the basics, you will have less
battery problems and will gain greater battery
performance, reliability and longevity.

What is proper operation of the mill?

How can I know my battery is being charged correctly?

How can I find a commercial replacement battery?

Can I test my own charging system?

We will discuss these and other questions in this article.


Battery and charging system operation
The alternator is designed to charge the battery when the engine has been started. When the
engine starts turning the alternator at a proper speed, the mill functions draw power from the
alternator's output (except hydraulic features). The surplus charges the battery. While the load is
less than the maximum output of the alternator, electricity is flowing into the battery. The battery
and the alternator share the load of the hydraulic features, which can draw much more than the
alternator's output. It is important to manage run-time of the hydraulic features. Excess hydraulic
run-time is the biggest drain on the battery because of the amount of charging time available while
cutting. When operating the hydraulics, you need to get the log into position with the least run-time
possible. The longer you run the hydraulics pump, the more energy must be replaced in the battery.
On our super mill, for example, when we activate the hydraulics, 300 amps are pulled out of the
battery. 140 amps are being put back in, leaving 160 amps not being replaced. The battery can
handle this load for a short period of time. By positioning the log quickly, you keep the 160-amp
draw to a minimum and battery charge is maintained. A battery that is allowed to remain partly
discharged for a short period will not charge fully again because of sulfation build-up.

Eighty percent of all battery failure is related to sulfation build-up. This build-up occurs when the
sulfur molecules in the electrolyte (battery acid) become so deeply discharged that they begin to
coat the battery's lead plates, and before long, the plates become so coated the battery dies. The
causes of sulfation are numerous:


    •   Battery sits too long between charges- as little as 24 hours in hot weather or several days
        in cooler weather.
    •   Battery storage allows a battery to sit without any type of energy input.
    •   Undercharging a battery, to 90% of capacity allows sulfation of the battery in the 10% not
        reactivated by charging.
    •   Heat of 100° F., or more, increases internal discharge. As temperatures increase, so does
        internal discharge. A new fully charged battery left sitting 24 hours a day at 110ä F for 30
        days would be unlikely to start an engine.
    •   Low electrolyte level-battery plates exposed to air will immediately sulfate.
    •   Incorrect charging levels and settings. Most cheap battery chargers can do
        more damage than help.
    •   Cold weather is hard on a battery. It's chemistry cannot make the same amount of energy
        as when warm. A deeply discharged battery can freeze solid in sub-zero weather.
    •   A parasitic drain can kill a battery in a weekend. A parasitic drain is a load put on a battery
        with the key off.

When extended run-times are necessary (as when cutting small logs), you should increase charge
time. Run the engine longer during breaks in cutting and on start-up and shut- down. Also, use a
trickle charger overnight every other day. If you are not going to be using your mill for an extended
time, it is best to put the battery on a trickle charger to maintain the battery voltage.

Vibration is another cause of low battery life. That is why a battery hold-down must always be in
place while towing. Rough terrain can affect battery life buy causing plate or separator damage. The
battery can bounce high enough to short out the posts and damage the battery or other electrical
components. The battery hold-down must be securely in place. Not all batteries are the same. When
choosing a battery, by the biggest battery you can find in size and Cold Cranking Amps (CCA) that
will fit in the battery box. A 1200 CCA battery, with a smaller case than the one we use, will not last
as long. There is less surface area and less acid storage area. Both are very important for high-
output use. The less surface area, the less reserve capacity will be available, and more heat will be
generated as the battery is charged and discharged. Heat is a battery's worst enemy. The climatic
conditions in your area dictate the minimum CCA rating necessary for proper operation. If you live
in a temperate region such as Portland, Oregon, a 950 CCA battery may be adequate for a Super
Hydraulic Mill with a diesel engine. But the same mill and battery in Great Falls, Montana, would not
start the engine in the extreme conditions possible there.

Freshness of a new battery is very important. The longer a battery sits and is not recharged the
more damaging sulfation build-up on the plates. Most batteries have a "date of manufacture code"
on them. The month is indicated by a letter- 'A' being January, and a number - '9' being 1999. The
letter "i" is not used because it can be confused with #1, so, C8 would tell us the battery was
manufactured in March 1998. Remember the fresher, the better. Average expected life of a battery
is 12 months if maintained in accordance with manufacturer's recommendations. If you manage the
charge state of your battery you may get a little more life from it. If you do not, expect a lot less
life. Charge a new battery before using it. It is very important to start with a full battery.


Battery Testing- A Few Basics
Safety first. Use caution when working with battery's. Refer to safety information in operator's
manual. The lead acid battery is made up of plates, lead and lead oxide (various other elements are
used to change density, hardness, porosity, etc.), and has a 35% sulfuric acid and 65% water
solution. This solution is called "electrolyte" and it causes a chemical reaction that produce
electrons. When you test a battery with a hydrometer, you are measuring the amount of sulfuric
acid in the electrolyte. If your reading is low, that means the chemistry that makes electrons is
lacking. So where did the sulfur go? It is stuck to the battery plates. When you recharge the
battery, the sulfur returns to the electrolyte.

Specific Gravity Test
First, fully charge the battery. The surface charge must be removed before testing. If the battery
has been setting at least several hours (I prefer at least 12 hours), you may begin testing. To
remove surface charge, the battery must experience a load of 20 amps for 3+ minutes. Running the
blade guide in and out for three minutes will do the trick.

Load Testing
Load testing is yet another way of testing a battery. Load test removes amps from a battery, much
as starting an engine would. A load tester can be purchased at most auto parts stores. Some
battery companies label their battery with the amp load for testing. This number is usually 1/2 of
the CCA rating. For instance, a 500CCA battery would load test at 250 amps for 15 seconds. A load
test can only be performed if the battery is near or at full charge. Hydraulic mill owners can use the
hydraulic motor to load test a battery. See below.


    •   Follow the Specific Gravity test above and charge battery if needed.
    •   Hook a voltmeter across the battery.
    •   With the loader in the down position, push down on the loader lever and hold for 20
        seconds, watching the voltmeter.
    •   Battery voltage should not fall below 10.5 volts. Replace the battery if it falls below 10.5
        volts in 20 seconds.


Testing the alternator
If you need to check the alternator, all you need is a voltmeter. Make sure you have a good battery.
Start the engine and engage the clutch handle. Set the voltmeter on DC voltage. Take the red lead
of the voltmeter and put it on the large red wire at the alternator. Put the black lead on the
alternator housing. With the engine at high idle, you should have a reading of 14.2 - 14.6 volts.
Take the voltmeter to the battery and place the red lead on positive and the black on negative. You
should be reading 14.2 - 14.6 volts. If not, you have a wiring problem to the battery. If you do have
14.2 - 14.6 volts and you still have slow function problems, test the battery.

With this information, you have a better understanding of how your mill battery and charging
system work. If you have questions about any of the information in this article, please contact
Wood-Mizer Customer Service at 1.800.525.8100.

								
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