Understanding Your Car Battery – Eliminating Battery Drain

Most car owner’s really don’t think too much about the battery – until it dies. How much do you really know about your battery? Routine check and maintenance of your Everett Car Battery can avert the unfortunate stranding incident in the mall parking lot.

SLI Battery

Automotive batteries are a type of rechargeable battery; the alternator recharges the battery when the car is operating. Also referred to as an SLI battery, indicating the specific functions, powering:

  • Starting
  • Lighting
  • Ignition

For electric vehicles, the battery may be a traction-type battery.


SLI batteries are usually comprised of six galvanic cells. Each cell provides 2.1 Volts, in series, the total voltage is equal to 12.6 Volts (6 cells x 2.1V), when fully charged. Diesel operated vehicles may actually provide 24 V by using either two-12V batteries or parallel “strings” of batteries to provide the necessary power.


  • Lead-Acid – plates of lead and plate-separators of lead-oxide are submerged in an electrolyte solution of : 35% sulfuric acid + 65% water. Electrons are produced from the chemical reaction, and electricity is produced as the electrons pass through conductors. The sulfuric acid reacts with the plates; as the battery discharges, the plate surface converts to lead-sulfate. Recharging the battery reverses the chemical process; converting the lead-sulfate back to lead and lead-oxide to repeat the process.
  • Sealed (Valve Regulated) – sometimes called “maintenance free”, sealed batteries use the same electrolyte solution. There are two types of sealed batteries: (1)  Absorbed Glass Mat (AGM) battery uses glass separators and; (2) a “gel cell” battery uses a fine powder to absorb and immobilize the sulfuric acid . Sealed batteries are more expensive and do not require monitoring of electrolyte solution.

Electrolyte Levels

Although more expensive, sealed batteries do not require addition of electrolyte solution. Additionally, there is no danger of spillage with the maintenance free type battery. Even modern car batteries have reduced the need for addition of distilled water by including additional electrolyte that is stored above the lead plates. For batteries with “open” cells, it is necessary to occasionally add distilled or demineralized water to supplement the electrolyte solution. Please note: the sulfuric acid in the electrolytic solution does not need replaced, as it does not deteriorate or get “used up” with charging – the chemical reaction of re-charging the battery maintains the H2SO4 (sulfuric acid) content of the electrolyte.


A car’s battery discharges each time you start the car, turn any lights on, turn the ignition to “on”, play the radio, etc. The battery is recharged when the engine is turned over, by means of the car’s charging system. If a light is left on for long periods of time, the battery can completely discharge, requiring an external recharge.

The discharged battery can be recharged by:

  1. Trickle Charger
  2. Slow-Charge
  3. Quick Charge
  4. Jump Start
If the battery has completely discharged, you may need to leave the engine running for a period of 20-30 minutes to fully recharge the battery.

Storing SLI Battery

An SLI battery will last longer if stored in a fully charged state. Over extended periods of time, a discharged battery’s sulfation will not be reversible through charging. Attaching a “float” charger to a stored battery will maintain the charge as needed. Alternatively, check the battery on a regular basis and recharge as required. If you are storing an automobile for long periods of time with the battery installed, it is recommended that the car be started and allowed to run for at least 30 minutes every three weeks to maintain the battery’s charge.

Removing/Replacing Battery

When replacing a car battery, always disconnect the ground terminal first to prevent short circuiting between the battery terminal and the car’s frame. If your car’s battery needs replacing, for safety reasons, it is best to call Snohomish Car Battery experts. Remember, some cars require a complete reset of radio stations, theft deterrent systems, etc. Check your Owner’s Manual for appropriate manner of restoring your car after a new battery has been installed.

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