All batteries, regardless of type, should be kept clean on the outside and should be kept tightly secured by a battery hold-down device. If not properly secured, battery acid can leak out, shortening the battery life. It will also discharge more quickly and the corrosive acid can eat away components under the hood. A battery that is not a maintenance-free type must be checked periodically for water level. A maintenance-free type battery usually cannot have water added to it, but it must also be checked for electrolyte level. This can be done by looking at the color of the "eye". If this battery is too low on electrolyte, sealed batteries must be replaced.
Except Maintenance-Free Batteries
Fill each cell to about 3 / 8 in. (9.5mm) above the tops of the plates. Always use distilled water because most tap water contains chemicals and minerals that may slowly damage the plates of your battery.Maintenance-Free Batteries
All later model vehicles were originally equipped with sealed maintenance-free batteries which do not require periodic attention as far as fluid level checks are concerned. However, the terminals require periodic cleaning which should be performed at least once a year.
CLEANING CABLES AND CLAMPS
See Figures 1, 2, 3 and 4
Once a year, the battery terminal posts and the cable clamps should be cleaned. Loosen the clamp bolts (you may have to brush off any corrosion with a baking soda and water solution if they are really messy) and remove the cables; negative cable first. On batteries with posts on top, the use of a battery clamp puller is recommended. Without the puller it is easy to break off a battery terminal if a clamp gets stuck.These pullers are inexpensive and available in most auto parts stores. Side terminal battery cables are secured with a bolt.
The best tool for battery clamp and terminal maintenance is a battery terminal brush. This inexpensive tool has a female ended wire brush for cleaning terminals, and a male ended wire brush inside for cleaning the insides of battery clamps. When using this tool, make sure you get both the terminal posts and the insides of the clamps nice and shiny. Any oxidation, corrosion or foreign material will prevent a sound electrical connection and inhibit either starting or charging. If your battery has side terminals, there is also a cleaning tool available for these.
Before installing the cables, remove the battery hold-down clamp or strap and remove the battery. Inspect the battery casing for leaks or cracks (which unfortunately can only be fixed by buying a new battery). Check the battery tray, wash it off with warm water and baking soda, rinse and dry. Any rust on the tray should be sanded away, and the tray given at least two coats of a quality anti-rust paint. Install the battery, and then secure the hold-down clamp or strap, but do not overtighten.
Reinstall your clean battery cables, negative cable last. Tighten the cables on the terminal posts snugly; do not overtighten. Wipe a thin coat of petroleum jelly or grease all over the outside of the clamps. This will help to inhibit corrosion.
Finally, check the battery cables themselves. If the insulation of the cables is cracked or broken, or if the ends are frayed, replace the cable with one of the same length and gauge.
See Figure 5
Check the specific gravity of a non-sealed battery (a diesel has two) at every tune-up for gasoline engines and at every oil change for diesels. It should be between 1.20 and 1.30 at room temperature. The specific gravity is checked with a hydrometer, an inexpensive instrument available in most auto parts stores, auto departments and many hardware stores. The hydrometer looks like a turkey baster, with a rubber squeeze bulb on one end and a nozzle at the other. Insert the nozzle end into each battery cell and suck enough electrolyte (battery water) into the hydrometer to just lift the float. The specific gravity is then read by the graduations on the float. Some hydrometers are color coded, with each color signifying a certain range of specific gravity.
All cells of your battery should produce nearly equal specific gravity readings. Do not be extremely alarmed if all of your battery's cells are equally low (but check to see if your alternator belt is tight); however, a big difference between two or more cells should be a concern. Generally, if after charging, the specific gravity between any two cells varies more than 50 points (0.050), the battery is bad and should be replaced.
Batteries should be checked for proper electrolyte level at least once a month or more frequently. Keep a close eye on any cell or cells that are unusually low or seem to constantly need water. This may indicate a battery on its last legs, a leak, or a problem with the charging system.
The maintenance-free battery cannot be checked for charge by checking the specific gravity using a hand-held hydrometer. Instead, the built-in hydrometer must be used in order to determine the current state of charge.Check the label on top of the battery for the proper "eye" color. In most cases the eye will be green indicating a good electrolyte level and state of charge.
JUMP STARTING A DEAD BATTERY
The chemical reaction a battery produces explosive hydrogen gas. This is the safe way to jump start a dead battery,reducing the chances of an accidental spark that could cause an explosion.Jump Starting Precautions
See Figure 6
- Be sure both batteries are of the same voltage.
- Be sure both batteries are of the same polarity (have the same grounded terminal, in most cases negative).
- Be sure the vehicles are not touching.
- Be sure that the vent cap holes are not obstructed.
- Do not smoke or allow sparks around the battery.
- In cold weather, check for frozen electrolyte in the battery.
- Do not allow electrolyte on your skin or clothing.
- Be sure the electrolyte is not frozen.
See Figure 7
- Determine voltage ratings of the two batteries; they must be the same.
- Bring the starting vehicle close (they must not touch) so that the batteries can be reached easily.
- Turn off all accessories and both engines. Put both cars in NEUTRAL or PARK and set the parking brake.
- Cover the cell caps with a rag - do not cover terminals.
- If the terminals on the run-down battery are heavily corroded, clean them.
- Identify the positive and negative posts on both batteries and connect the cables in the order shown.
- Start the engine of the starting vehicle and run it at fast idle. Try to start the car with the dead battery. Crank it for no more than 10 seconds at a time and let it cool off for 20 seconds in between tries.
- If it doesn't start in 3 tries, it is likely that something else is wrong.
- Disconnect the cables in the reverse order.
- Install the cell covers and dispose of the rags.
Generally, a battery should be charged at a slow rate to keep the plates inside from getting too hot. However, if some batteries are allowed to discharge until they are almost "dead", they may have to be charged at a high rate to bring them back to life. On maintenance-free batteries it may be necessary to tip the battery from side to side to get the "eye" to indicate the state of charge.
Always connect the battery charger according to manufacturers instructions.
When battery replacement becomes necessary, select a battery with a rating equal to or greater than the one which was originally installed. Deterioration and aging of the battery cables, starter motor, and associated wires makes the battery's job harder in successive years. The slow increase in electrical resistance over time makes it prudent to install a battery with greater capacity than the old one. Details on the role the battery plays in the vehicle's electrical systems are covered in Engine & Engine Rebuilding of this information.
- Carefully disconnect the negative cable from the battery terminal.
- With the negative battery cable disconnected and out of the way, carefully disconnect the positive cable from the battery terminal.
- Loosen the nut and/or bolt retaining the battery strap or clamp. Remove the battery retainer.
- Wearing an old pair of work gloves or using a battery lifting tool, carefully lift the battery out of the vehicle and place it in a safe location. Be sure to keep the battery from open flame and to protect surrounding areas from acid.
- Inspect the battery tray and cables for damage and corrosion. As necessary, clean or repair the tray and cables.
- Carefully lower the battery and position it in the tray, making sure not to allow the terminals to short on any bare metal during installation.
- Position and secure the battery retainer strap or clamp.
- Connect the positive cable to the positive battery terminal.
- Connect the negative cable to the negative battery terminal.