What is Start/Stop?

Power - by Joe Weber - updated on 1/30/2024

Chances are if you own a new car or have driven a car made in the last decade you've probably experienced start/stop. If you weren't aware of what start/stop is it may have triggered some worrying thoughts when you first experienced it. But rest assured it is completely normal and is there to help you and the environment.

The technology has been around for a long time, although only been mass-produced in recent years. The first production car with this technology was the Volkswagen Polo in 1983 across the pond to help combat Europe's high fuel prices.

What Does Start/Stop Do?

It has a few names: Start/Stop, Stop-Start, Auto Stop and probably some others. In truth, they all do the same thing. When you are driving and you pull up to a red light and depress the brake pedal, as the car comes to a complete stop the engine will shut off. The rest of the vehicle's electronics will be working, like the A/C, radio, heated seats, etc. but the engine will be off until you take your foot off the brake.

How Does Start/Stop Work?

When your vehicle comes to a full stop while driving, Stop/Start technology (if equipped) can shut down the engine automatically. The tachometer needle will shift to the "Auto Stop" position and you will hear the engine stop running during this process. In typical driving situations, the engine automatically restarts when you release the brake pedal.

Sensors oversee both the vehicle and battery systems, initiating engine shutdowns and restarts as necessary to ensure passenger comfort needs are met. Stop/Start Technology engages automatically, eliminating the need for any manual intervention or constant monitoring of battery power.

To keep the battery healthy, the use of A/C or other accessories for a longer period may make the engine start again before you let go of the brake.

You may have two batteries

On top of built-in safeguards to keep your battery healthy, some models take it one step further and add what's dubbed an "auxiliary battery" to the system.

Auxiliary batteries are designed to act as a backup to the starting battery to provide power to essential features like start/stop and other systems that require power while the engine is off. This helps put less strain on the main battery and charging system.

Are There Benefits to Start/Stop?

There are several reasons why having Start/Stop equipped is a benefit to you, the driver and those around you.

1. It reduces pollution: Keeping a car running while idle generates unnecessary pollution, but by shutting it off, you can eliminate the production of pollutants.
2. Less fuel consumption: Granted it's not a huge number, but vehicles using Start/Stop technology do enjoy a slightly longer amount of time between fill-ups.
   1. According to research conducted by the Society of Automotive Engineers  , implementing start-stop technology can result in a more than eight percent improvement in a car's fuel economy during heavy traffic conditions.
3. It's quieter: For your comfort when you are at a red light and the engine shuts off, it's much quieter so you can converse with friends and family more easily.

Are There Downsides to Start/Stop?

It's not a perfect system and using Start/Stop regularly can have some negative effects.

1. Additional wear on the battery: Stronger batteries are required in vehicles that are equipped with Start/Stop technology, mainly AGM batteries that can withstand the increased power demands.
2. More robust components are necessary: Due to the increased demand for the starter and other ignition components, vehicles with Start/Stop are built with stronger parts to withstand the increased use. This makes the parts more durable but it also increases their cost when replaced.
3. Personal preference: This last one is quite simple. Some people just really don't like that the car shuts off at the light. It makes them uneasy and they would rather the engine stay running the whole time.

Can You Turn Start/Stop Off?

A select few makes and models do give you the option to disable the auto-stop feature. In most vehicles that allow you to disable the Auto Stop feature, you will see a button somewhere on the dashboard that looks like a capital A with an arrow surrounding it. See below for an example. Sometimes it also includes the word "Off".

There are third parties that claim to have a solution for this by altering the computer programming but tread lightly, it's not always a great idea to mess with sensitive electrical systems and you could cause more harm than good while also voiding any warranties you have on the vehicle.

Do Cars with Start/Stop Use Different Batteries?

Because of the increased power demands that Start/Stop systems put on the battery, more robust batteries will be used. Vehicles with Auto Stop equipped almost always come with an absorbed glass mat (AGM) battery from the assembly line instead of a traditional flooded battery.

Why are AGM batteries better for these vehicles?

AGM batteries boast some fantastic features and upgrades over conventional batteries which makes them the ideal battery for these vehicles.

• More power - AGM batteries provide more electrical energy than flooded batteries, making it easier to start vehicle engines and providing additional power for additional power demands like start-stop systems.
• Faster recharge - AGM batteries can charge up to five times faster than conventional flooded batteries.
• Long lifespans - AGM batteries last up to three times longer than flooded batteries. Their long lifespans are much more cost-effective in the long run.
• Slower discharge - AGM batteries hold their charge longer when not being used and are more likely to be recovered if they become completely drained.
• Spill-proof - AGM electrolyte is held in place by the fiberglass plate separators and the battery is completely sealed.
• Less corrosion - Thanks to being completely sealed, this type of battery is less likely to form a buildup of corrosion on the terminals than their flooded counterparts.
• Temperature resistance - AGM batteries do a much better job of standing up to the negative impact of extreme cold and heat.
• Vibration resistance - AGM batteries are much more resistant to vibrations and rough roads.

Have Your Battery Tested Early and Often

Even with the added stress on your battery, batteries in vehicles with Start/Stop should still last you around 3-5 years with minimal maintenance. That doesn't mean you can just ignore your battery until it dies. The best way to stay on top of issues before they even pop up is to test your battery or have it tested by the professionals at your local Batteries Plus.

Testing early and often is an easy way to identify weak points to address to keep your battery healthy and even extend its usable life to keep your wallet happy and your life a little less stressful.

Special Note:
If you're one of the lucky ones with two batteries, starting and auxiliary, don't forget to test both of them when you test them yourself or have them tested professionally.

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