727-228-6012

St. Petersburg Auto Electrical Repairs & Battery Service

Today's Mercedes Electrical Systems Are Getting More Intricate, PPI Knows How To Fix And Diagnose Electrical Systems.

Electrical systems are stressing the limits of current technology. The major components of your autos electrical system are explained below.

The battery is a storage device, some are 12 volts and some are much higher.  It is used to start the engine and help operate the electrical accessories installed on your vehicle.

Some batteries use a gel or mat to replace the electrolyte for a somewhat safer battery and the use of "maintenance-free" batteries has eliminated the need for refilling the electrolyte. However, all batteries loose charging capacity over time through the loss of chemical reaction, deterioration of the plates and chemical breakdown of the connections.

Before replacing any battery due to a failure, have the battery and the car's electrical system tested for proper functioning. Replacing a dead battery only to have another a few weeks later due to a weak alternator or a parasitic drain on the system is not only frustrating but can be expensive and dangerous as well.

An average battery should last 3-5 years in average climates. The replacement battery should always have the same or higher CCA rating (cold cranking amps) as the original and be of the same or compatible "group size" to fit the battery tray, cable connections and hold down mounts.

The alternator produces electricity used to maintain battery storage charge and to help run all the electrical accessories, including the ignition and the engine control systems. It is belt-driven by the engine and produces an alternating current (AC), which is converted internally to between 12 and 14 volts direct current (DC) by the diode bridge or rectifiers.

Understanding the importance of having an operational warning light for the alternator is crucial to catching problems early. In many systems, the electrical current passing through the filament of the warning light is what energizes a circuit in the alternator to start charging.

It is also important to check the fuse that controls the light circuit, as well. This fuse could be labeled differently in various cars. It could be labeled "charging", "regulator", "meters", "gauges" or "engine".

Checking out these simple circuits first can protect against unnecessary replacement of your alternator.


A thorough diagnosis is always the best route to determining whether or not the alternator is at fault.

The Starter is another major electrical component in your autos electrical system. Although it is used only a few times a day, it is the single largest power user and most critical to your Mercedes-Benz operation. The starter is simply a DC motor that turns the engine crankshaft through the flywheel, starting the combustion process by creating compression within the cylinders. In plain English, that means, it gets your engine to spin fast enough to fire-up.

Voltage to the starter is supplied from the battery and is controlled by a relay and/or solenoid controlled by  the Electronic Ignition Switch or EIS  or ignition switch inside your Mercedes-Benz.

Starters can be of varying types and designs - gear-reduction types for higher torque, permanent-magnet types to reduce size and weight, or just plain, old-fashioned heavy starters. But whatever the type, they all function in the same basic way.

A slow cranking engine may be a sign of a bad starter and with age, that's more and more likely. But on most cars today, it's due to low battery voltage, poor electrical connections at the battery or a failed relay or fusible link.

Most starters will easily outlast a new vehicle warranty if it's not overused, if good connections are maintained and if it's not overheated through dirt and grime buildup.

Starting an older Mercedes-Benz with the major components turned off (like the AC compressor, blower motor and high-powered stereos) will greatly ease the load on the starter. But newer cars , In fact , have "lock out" relays that will not allow the AC compressor and alternator to turn on and drag until after the engine has been started. So no need to adjust settings such as AC when turning off and re-starting the engine. 


Get Your Mercedes-Benz Serviced The Right Way,
Call (727) 914-8968