A car battery that dies while driving is one of the worst things. What a way to ruin your day. The thing with car batteries and the charging system is they give indicators of a problem, such as the charging indicator on the dashboard. Ignoring the light will lead to issues such as the car dyeing as you drive, which are explained in more detail below.
Can a dead battery cause a car to die while driving?
It is an unusual scenario for a car battery to cause a car to die while driving because once the vehicle has started, it is not required until you turn the car off and start it again. When the engine runs, the alternator takes over, and a sufficient electrical load is produced to power the vehicle and auxiliaries.
It is more common to find the alternator is no longer producing the charge required to keep the car going than the battery causing the car to die. Even something as simple as the serpentine belt snapping, meaning the alternator is not running while driving, is much more common.
How can a car battery die as your drive?
A car battery draining as you drive will cause electrical components to struggle; for example, the headlights will dim, and the windshield wiper will struggle. This happens because the parasitic load from these running electric components drains the battery’s remaining charge.
The alternator should be contributing to putting an electrical load back into the battery; either it is not producing enough, or its internals have failed. With a faulty internal battery cell or dodgy connection, the charge in the battery will be displaced.
Eventually, if you continue ignoring all of the warning signs, the battery will no longer have enough amps to power the coil pack and spark plugs, and the car will stall .Once the vehicle has stalled because of a failed battery it will be challenging to get the car running again; even a jump start may not work.
A car batteries role
The car battery stores the charge produced by the alternator so that when you come to start the vehicle next time, you have enough power to turn the car over. The battery’s charge is constantly replaced as you drive because a load will always be drawn from the battery to power the heater, the lights, the indicators, etc; the alternator carries out the charge replacement.
With the car turned off, the car battery also has another job of powering the car’s security system and electric components that require a constant current like a clock. This is one reason the car battery drains as soon as you turn the car off, but the amount being drawn is insignificant unless the battery is bad.
Signs of a bad battery
The signs of a bad battery are similar to an alternator, so it is important not to misdiagnose the two problems. Bad batteries symptoms include:
- Failing to turn over
- Failing to charge after starting
- Needing to jump-start to get the car running
- Sporadic electrics
- Car clock stopped working
The alternators role
The alternator provides power to the vehicle once the car is running. Although this power is distributed from the battery, the current is produced by the alternator, the vehicle’s electricity generator.
A good alternator will always produce a higher voltage than the battery’s requirement. A good alternator will charge at 13.4 to 14.4 volts even though the battery’s capacity is 12 volts. This ensures it overproduces power for the components; what’s left of the current consumed is then stored in the battery until the vehicle is next started.
Signs of a bad alternator
Battery and alternator faults come hand in hand. Both components work together to keep the car running, so the other will fail without one. Typically if a battery dies, you may find the cause is the alternator not putting enough charge in. The typical warning signs to look for:
- failure starting the car
- Dimming lights
- Sporadic electrics
- Battery charging light illuminated
- Burning smell from the engine bay
What should you do if you the car battery drains while driving?
Using as little electricity as possible while driving should allow you to continue your journey. If the rate of the car battery draining is causing you a problem as you drive, you should pull over safely and call roadside recovery. If you continue driving, you risk the battery failing and the car coming to a standstill. Depending on the transmission type, moving an automatic with a flat battery is not always straightforward.
The car battery will need replacing, at which point you can check or have the charging system checked for faults.
Ignoring a failing car battery’s symptoms could result in problems such as the car battery dying while driving and the car stalling, although this is the worst case. The car battery will usually drain because of charging system issues. So, if the warning light does come on, it’s best to get the car inspected asap and save yourself from problems while driving.