Skip the auto shop - Our mechanics make house calls

Symptoms of a Bad or Failing Auxiliary Battery

auxiliary battery

For most diesel engines, having two batteries is essential due to the number of components that need power. The main battery will run continuously, while the secondary auxiliary battery will get a trickle charge from the main battery. When the main battery is depleted, the auxiliary battery will kick in and continue to charge the car as needed. Just like the main battery, eventually the auxiliary battery will start to have issues and will need to be replaced.

Usually, these batteries will give you fair warning that they are in need of replacement. Taking notice and acting before the dead batteries leave you stranded on the side of the road is very important. Without properly working charging components, it will be nearly impossible for a vehicle to run like it is supposed to.

1. The vehicle won’t crank

Having a battery that is dead will result in you not being able to crank the car when needed. Usually, the car will run once it has been jumped off, but will quickly die back out after it is turned off. This is due to the fact that while it is running, the alternator of the vehicle is giving it the charging it needs. Once the alternator stops, the cells in the battery will not be able to hold a charge and will cut off.

2. Noticeable leaks around the battery

The fluid that is in the battery in your vehicle is very important because without it the cells of the battery will burn out. If you start to notice that this liquid is leaking out, then you will need to act fast to get the battery replaced. Getting this battery fluid on other parts of the engine can be very harmful due to the corrosion that it can cause.

3. The Battery Light is on

A fully charged battery will allow all of the components of a vehicle to function properly. Without a full charge, there will be a number of things that will not work or that will perform at a fraction at what they normally do. The Battery Light will usually come on when there is an issue with the charging system of a car. Getting both the battery and alternator checked will help you to narrow down where the problem lies.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Post a question and get free advice from our certified mechanics.


More related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...

Related questions

Q: why does my battery keep going dead?

The best way to diagnose the type of issue your Hyundai is having is by beginning with using professional level test equipment to verify that the battery, charging system, and starter are all functioning correctly. These testers are widely...

Q: Car not starting in temperatures over 80 degrees

Hi there. This can be a common issue that vehicles encounter when the temperature outside is warm or if there is a sticky starter solenoid. The solenoid will stick even if sufficient current is applied to its switch. I'd suggest...

Q: How Long Does a Car Battery Last?

Whether you drive a vehicle for work or roaming around town running errands, one constant reality is that we all depend on our car's battery to start the vehicle on the roads we travel. However, one of the frequently asked...