Electrical: Battery

What it Does

The battery stores the electrical power necessary to start the engine.

Why This Matters

The battery is responsible for delivering power to crank the vehicle’s engine. It also needs to maintain sufficient power supply to properly power-up other components during the engine start sequence.

Possible Problems and Concerns

Failed battery (severe):

The vehicle will not start because there simply isn’t enough power to crank the engine, or crank it quickly enough for the engine to start and run on its own.

Failed battery (partial):

The vehicle will start sometimes without assistance but will be prone to needing jump starts or battery charging depending on set time in between drives and the battery’s state of charge. This should still be considered a failure since the vehicle cannot be trusted to start reliably.

Weak battery (low cranking voltage):

The vehicle still starts, but cranking voltage dips too low as the engine cranks. This can result in chattering or scorching of the high amperage electrical contacts in the starter motor because there is not sufficient electrical energy being applied to hold them firmly closed. Scorch damage to these contacts will result in the need to replace or repair the starter motor.

Weak battery (excessive amperage demand):

The battery starts the vehicle, but it pulls an excessive amount of amperage from the vehicle’s alternator in order to stay charged. This can shorten the lifespan of the alternator.

Acid Leakage:

Leakage of battery acid past one or both battery posts is a common thing to see. The acid is corrosive and damaging to metal. It is common for it to damage battery cable terminals, and it can also damage battery tray bolts.

Intermittent Severe Failure:

This is rare, but it does happen. In this condition, the battery alternates between being able or not able to start the vehicle. This is due to internal battery failure that cannot be observed from the outside. The battery may also pass a sequence of battery tests before it goes back into failure mode, and that failure mode may be short-lived or very sporadic.

Finite Lifespan:

Batteries always have a finite lifespan. In Florida’s hot climate, even the best batteries may not offer much more than a 3 year service life, especially if the goal is to retire the battery from service while it is still in good condition (again, a weak or partially failed battery can cause problems for other electrical components.)

Unpredictable Failure:

Modern vehicles generally start very quickly. Engine cranking time is short, and this often masks a weak or failing battery. It’s not uncommon for a battery to go suddenly from being able to start the vehicle to not being able to. You don’t always get much (if any) warning.

Non-Reliable Test Results:

After a battery has significantly aged, be careful about relying on test results. A battery in marginal condition can pass multiple tests and fail shortly thereafter. Generally speaking, a battery that is well-tested is not going to suddenly fail the next day, but an aged battery may pass tests and still give up within the next 3-6 months.

Recommended Parts Brands

  • OE Grade (for some applications)
  • East Penn.

Repair Notes

Poor installation practice can damage batteries and cable ends. Over-tightened hold-downs can encourage acid leakage due to deformation of the battery case. Installation of the terminals up high on the battery posts (where they are thinner) can stress the terminal and alter its shape.

A Recommendation

Consider having your battery replaced every 3 years (and possibly sooner if the battery in your vehicle is not a high-quality battery). Batteries have finite lifespans, and battery failure is one of the most common causes of a no-start problem. While it may feel strange to remove a battery that is still starting the vehicle, you may actually save a substantial amount of money and time in not having to deal with surprise break-downs, missed appointments, tow bills, and shop visits. It is no waste to replace a 36 month battery that may only have another 3-6 months to live, and again, battery tests cannot reliably predict the end of life for an aged battery.