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Tuning Up Your Tractor (Part 5)
Buried somewhere beneath the sheetmetal, under the gas tank, or stuffed in front of the radiator is the battery. This elusive and neglected component of the tractor is the hardest to get to when it is dead and in need of a jump. But usually, the storage battery is a storehouse of electrical energy waiting to be released a the flick of a switch. A few maintenance tips and periodic cleaning will keep it charged for the duration of its life span.
The battery is made up of a number of lead based plates submersed in a solution of suphuric acid. One set of plates, the positive ones, comprised of lead peroxide, are separated by an insulating material from the second set of plates made up of sponge lead. Each of the separate plate sections are connected together by a positive or a negative lead lug. This insulated and autonomous unit is called a cell. When submerged in battery acid, a mixture of about 38 percent sulphuric acid and distilled water, it creates a potential of approximately 2.1 volts across the cell. The voltage is pretty uniform regardless of the number of plates used as it is a result of a chemical reaction, not a result of plate volume. But, the more plates that are found in each individual cell, the more amperage capacity the battery will have. Three of these cells combined together in series create a six volt battery, six connected together make a twelve volt battery. The hard black plastic case provides the inert mounting skeleton for the individual cells and gives a solution tight container for the acid. The battery terminals protruding from the case are for the respective positive and negative sections of the cells. Note that the positive battery terminal is always larger than the negative terminal.
Even though the battery appears tough and rugged it is important not to wrestle and jostle it around. As a battery ages sediments from the charging and discharging cycle collect in the plastic grid at the bottom of the cells. Shaking or rough handling of an older battery can loosen some of this material and cause it to lodge between the positive and negative plates. This can short out a cell and ruin the battery. When viewing down the cell filler plugs a cloudy appearance of the acid solution can indicate a shorted cell.
As mentioned earlier, the amount of lead plates in each cells determines the amperage capacity of that cell. Therefore, a high amp battery will have a larger number of lead plates in the cell than a lower capacity battery. Sometimes, though, this extra number of plates has to be installed in a battery case of the same size as a lower capacity battery. In order to do this the battery company makes the thicknessí of the lead plates thinner so as to fit more plates in the same area. There is only so much capacity that can fit into a given space. That is why tractors or trucks with large engines that require large electrical capacity to start have two or more large batteries. The extra plates needed to create the necessary capacity and give adequate battery life before the plates disintegrate from the chemical reaction require the added size. Take care in moving around the higher capacity batteries because the cell structure with added plates tend to make them a little more fragile.
Many tractor and truck batteries have the filler plugs or ports in them as previously mentioned. These ports have a dual purpose. When a battery discharges and recharges the chemical reaction process produces hydrogen as a by-product. The filler caps provide venting for this highly explosive gas to the atmosphere. When working with a battery always make sure any electrical load is turned off before removing the battery terminals. When charging a battery take care to unplug the charger when connecting or disconnecting the charging clips to the battery terminals. Even the smallest of sparks can ignite the escaping hydrogen and cause the battery to explode. When jumpstarting the battery, instead of clipping the negative clamp to the battery terminal, clip it to a grounded bolt or engine component away from the battery location. The corresponding spark from the charging vehicle will be controlled and isolated away from the battery, thereby avoiding a potential explosion. The second use for the ports is so one can replenish the water supply in the battery. Make sure and use only distilled water. Regular water from the tap can have impurities in it that will shorten the cell lifespan. Dissolved lime, for instance, can neutralize the suphuric acid if used in sufficient quantities. Other impurities can coat the lead plates with a microscopic film and reduce the effectiveness of the electrical reaction. Make sure and not overfill the cell; fill it to the base of the plug hole, and try to fill the cells while they are in the charging mode.
Now that we have a basic understanding of the battery lets discuss in further detail about its maintenance. An often neglected component of a battery is its holddown straps. An unsecured battery is an accident waiting to happen. The bouncing of a vehicle, especially a tractor over a plowed field, can cause a battery to scoot around in its housing and possibly short out against another metal component causing a fire. If not that, it can certainly break a terminal, cable, or case. Purchase a battery hold down kit and install it. It is cheap insurance against tractor damage and will increase the life span of the battery. Another great investment is a battery terminal remover tool. This cool tool looks like a small gear puller with clamps. After the terminal bolt is loosened, the puller makes removal of the terminal an easy job. Donít screw a stuck terminal back and forth or use a screwdriver to try and pry it off. You can inadvertently crack the battery case or break the seal between the case and the protruding terminal. A puller is cheap, easy to use, and does the job correctly. Once the terminal end is removed, inspect the mating ends for corrosion, pits or cracks. A battery terminal cleaner works great for removing corrosion build up. This tool has two wire brush ends; one male, the other female. Use it to brush the ends until they shine. Sometimes a terminal end will have a hard blackish coating on it. This lead oxidation stops the electricity from flowing and creates excessive heat at the connection. It wonít always come off with the wire brush so you may have to use a small file. Make sure to rotate the file around the terminal as you go so you wonít create a lot of flat spots. Donít remove too much material, then tidy up the terminal with the brush. If the bolt is corroded, replace with a new one. Excessive corrosion on the cable terminal can be removed by submersing the end in a coffee can of water and baking soda solution for a while. Remove, dry and then wire brush the mating parts. Terminal ends that are pitted, cracked, or missing due to acid corrosion, should be replaced. It is best, in the long run, to replace the entire cable rather than merely an end. If the terminal end needs replacing, the chances are good that the reason for damage has made its way up the cable under the insulation where it canít be seen. Examples could be unseen corrosion damage, copper strands that have been too hot from resistance and have burned themselves into the insulation, or have been heat damaged, or have internal strand breakage.
After removing the hold down strap and terminal ends, remove the battery from the tractor and place on a plastic box or covering. Hose down the top of the battery and brush off the accumulated debris. Take a towel and dry off the entire casing. Remove the filler ports and check the levels. Place on charger and fill accordingly. One way to test the integrity of the battery is to check the specific gravity of each cell. A hydrometer, available at local auto stores, will measure the electrolyte acid content. It is best to read the directions that come with the tester thoroughly as variations due to temperature and states of charge can make the readings hard to interpret accurately. An easier method to determine battery integrity is to do a load test. With the battery installed in the vehicle, attach a voltmeter to the battery terminals. Ground the coil to keep the engine from starting and crank the motor over for 15 seconds. If the battery voltage stays above 9.6 volts, then the battery is in a reasonable state of charge. Below that amount indicates a shorted cell or a lowered capacity due to the battery reaching its useful life.
When reinstalling a used or new battery, use a terminal conditioner on the cable and terminal ends. The conditioner comes in a spray can and goes on like a red paint. The coating retards battery acid corrosion and lead oxidation and will lengthen the time between cleanings. One can also install felt pads onto the battery posts which have been saturated with baking soda. These also tend to retard acid corrosion. The negative cable has the smaller end and goes to the corresponding terminal. Donít drive the terminal ends onto the posts using a hammer. The jarring action may damage the internal connections of the battery. Instead, use a terminal spreader. Donít overtighten the terminal bolts as you can cause stress cracks on the ends. Reinstall the hold down brackets or straps making sure not to overtighten which can cause warpage and/or breakage of the battery case.
If a battery is to be removed for the winter months, take a few moments to ensure that it will be in good condition when spring comes. Clean the casing and dry with a towel. Clean the terminal posts and check the electrolyte level. Place the battery off of the floor, preferably on a wooden bench or shelf. Batteries left on concrete floors will lose their charge in a few short weeks. Place a trickle charger on the battery to bring it up to charge. Some chargers have an automatic shutoff switch that will shut the unit off when the battery comes up to a full charge, and then turn it back on when the charge falls below a predetermined level. This type of charger can be left on all the time. Other chargers must be removed to prevent overcharging. When the battery is fully charged store it in a cool, dry location out of the way of kicking feet or falling tools. A light coating of petroleum jelly on the posts will prevent any lead reaction to the elements. When spring comes the battery should be ready to go back to work for your tractor.