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The state of your car battery is critical to the running of your engine and just as important to other components like brakes & air bags. The battery is probably one of the most mis- understood & overlooked components in engine performance.

In this blog we will see what the other components rely heavily on the battery performance & how the battery can affect your fuel economy.

In simple terms a battery is a pressure vessel- which is made up of 6 x 2-volt cells=12 volts.
Like the heart in your body its supply’s voltage(pressure) to every component in your car- any thing that is & can be switched on is supplied by the battery.

As I have written many times before a car is a vehicle made up of different systems, but each system now has electrical monitoring systems which are fed back to the computer.

So how does a 12volt battery help make 20 000 volts at the spark plugs?
Through a series of primary windings transferring through a series of secondary windings in a ignition coil a high voltage spark is produced.

Ok that’s great, now if a battery is underperforming. & Say instead of 12 volts we now have 11 volts what happens is the voltage is lower- hence pressure is lower to push things, therefore the current- the amps will be lower & resistance will get higher. In a nutshell this slows everything down- with our example of voltage step up from 12 volts to 20 000 volts the time to produce the spark will take longer & even produce a retarded spark.

Fuel injectors rely critically on battery voltage when starting- injectors do not open straight away- they have a minuscule lag called dead time- when the battery is failing this is directly proportional to the dead time & increases it- when the injector eventually does fire the full stream of fuel can possibly miss its window this can cause lean misfire, or the vehicle will not start.

Battery voltage is constantly reviewed by the computer as a reference voltage in other words it’s a comparison voltage this voltage is then compared by active data voltage monitoring for air bag deployment, antilock braking & cruise control to name a few. The engine computer will have no hesitation to switch on a engine light when the it detects the battery charge not being consistent.
I once saw a classic Simpson cartoon where Homer had a car crash hit is head on the steering wheel & then the air bag went off- poor Homer!

Sure, it’s funny but that is the last thing you want to happen.

Testing a battery

There are many ways to test battery.
Personally, I like to check the battery, alternator on a Pico lab scope which gives me real time data.
Then I like to put a battery underload- simulating a starter motor current draw or even just a tad more.
Personally, if your battery is 3 years old or older-get a new battery do not muck around- because it will breakdown on you…


Simply a tired battery cannot perform- everything slows down or misses its mark to perform this can cause poor performance & poor fuel economy- the injectors are slower to inject fuel, the fuel pump does not rotate as quick the spark losses its saturation moment to produce s strong spark & with smart locks, smart keys its only getting more involved & reliant on battery performance.
Constantly ask for a battery check & report@ every service & once again if your battery is over 3 years old get a new one- it’s the world we live in now- Manny