Evoque Auxiliary Battery Purpose and Common Problems Explained

Your Range Rover Evoque's auxiliary battery provides exclusive power to the auxiliary BCM. In turn, the aux BCM will give power to the TCM (transmission control module) and gearshift module/mechanism. The aux battery may also power up the Eco Stop/Start function.

Auxiliary battery highlights

• Purpose:start-stop, auxiliary power source
• Average lifespan:3-4 years
• Types:AGM, EFB
• Location options:behind bumper, in trunk, near main battery
• Reasons for failure:age, drain, loose contacts
• DIY replacement:possible but may be complicated
• Average price:$100-$180

Why a Secondary Battery Is Essential in a Vehicle

Having two batteries in your Range Rover Evoque is important because of the many vehicle parts or areas that require power. The primary battery will work continuously, while the secondary (aux) battery will receive a trickle charge from the primary unit.

The secondary batteries in some vehicle brands and models are like substitutes during a soccer game. They'll be activated when the power of the main battery has been used up.

However, just like the primary unit, the secondary one can also develop faults that may require it to be swapped out. You have to learn how to discover or notice the potential symptoms.

Thankfully, the battery usually gives warning signs like error codes. But everything may seem to be working fine even with the error codes being produced. It's your responsibility to quickly act on the alerts you get or the symptoms you observe. Hopefully, the need for a costly battery replacement can be avoided.

Keep in mind that the aux unit won't perform well if it isn't being charged properly by the main battery. The same also goes for when it's experiencing low voltage.

How the Range Rover Evoque's Auxiliary Battery Works in the Dual Battery System

Aux batteries vary in size, specification, and function. This depends on the demands placed on the unit in the vehicle's electrical system. For example, as stated in the introduction, some deal with the transmission/gearshift, while others are for the Eco Stop/Start feature.

A dual battery system is engineered to isolate the power supply-sensitive electrical parts that may be adversely affected by the main battery's low voltage when starting the vehicle. Two contact switches may be utilized in redirecting the power supply into two different circuits on starting your engine.

Energy will be supplied to the sensitive electrical parts from the aux battery as the engine starts. The main unit, on the other hand, will perform its role of supplying power to the starter and maintaining the flow of energy to the EMS (engine management system).

The voltages of the main and aux batteries will be monitored to make sure that there's adequate voltage available for the next time you start the vehicle. Energy will be supplied to the latter if necessary.

Symptoms Associated with Range Rover Evoque Auxiliary Battery Faults

Issues with the Evoque's aux battery could sometimes log error codes into the vehicle. It would seem as if they're coming up for no reason. This is because everything with the gearshift, trans, or shifting may seem fine.

But don't take the logged codes for granted. Find out what's causing them to spring up or call a professional mechanic to help in the investigation. Below are the symptoms of the Evoque's aux battery that you may notice at any point in time.

1) "Gearshift Config" Error Code

You may be seeing this code come and go which may seem strange. It's a warning that there's a problem with the aux battery and you'll have to replace the unit or fix any loose connections to resolve the issue.

Note: There was a recall concerning the dual battery electrical connection.

What Is a Gearshift?

This is a mechanism by which the trans gears in a power transmission system are engaged or disengaged. It's also referred to as a lever for regulating the trans gears.

2) Code for the Paddle Shifters and Cruise Control Buttons

This code may be indicating that there's a fault in those systems, even if they seem to be working fine. You may be thinking that there's a loose aux battery connection somewhere, and you could be right. Look for the loose connection or any other possible source of the problem.

What Are Paddle Shifters?

Paddle shifters can be referred to as buttons or "paddles" that are mounted on or near the steering wheel. They allow an Evoque user to switch gears manually while his/her hands remain on the steering wheel.

In other words, paddle shifters essentially replace the center-mounted trans lever and ensure that shifting is done without your direct input. They facilitate better control than the traditional automatic trans.

What Is Cruise Control?

Cruise control helps you when driving at a constant speed. It's an electrical system that lets you set your Evoque to a specific speed so that you won't have to use the accelerator pedal. This will help in relieving foot stress and fatigue.

Shifting is easy, smooth, and quick with the above features. This is why you have to fix the problem with the battery ASAP so that there won't be any issue with the two buttons mentioned above. It's only a matter of time before the seemingly fine-working paddle shifters and cruise control buttons start displaying obvious malfunctions.

3) Low Voltage

The low aux battery voltage will log in all kinds of error codes associated with the trans or gearshift system. So you'll have to deal with each code one after the other.

Test the battery's voltage to be sure that it's reading is 12.5 volts. If it's not, then the unit has an issue and it will need to be replaced. A loose connector at the unit could create this condition and the battery won't be able to perform its roles at all or effectively.

4) Shifting Issues or Problems with the Transmission

One obvious sign of a problem that's associated with the aux unit is a shifting abnormality or problems with gear shifting. After all, the battery control module which regulates the transmission control module won't be functional or may malfunction. This will surely mess up the transmission's functions.

5) Inoperative Eco Stop/Start Feature

This symptom may register a (DTC) diagnostic trouble code and it can be as a result of a bad connection in the dual battery junction box. The box will have to be changed so that things can come back to normal.

What Is the Eco Stop/Start Feature?

The Stop/Start feature on your Range Rover Evoque helps in enhancing fuel economy, saving power, reducing C02 emissions. For instance, the feature will disable the engine when you slow down to a stop from a speed of more than 2.5 miles per hour.

The engine will remain stopped as long as your foot is on the brake pedal and it will restart automatically once your foot is released. The vehicle has to be in sport mode or "drive".

Location of the Auxiliary Battery

The aux battery of the 2015 Evoque and earlier model years is situated next to the main battery under the hood. Evoque vehicles issued in later years have the aux unit positioned underneath the glovebox area (passenger side) in a hidden place.

You'll have to get certain components out of the way to access the aux battery. It may not be as simple as it is to get to the main one. Don't try to do this with adequate DIY knowledge about the procedure. And since there are two possible locations, your DIY technical know-how may be limited to only one approach.

It's best to hire an expert to inspect the battery because you may overlook some aspects that only an experienced professional wouldn't take for granted. And of course, you won't have to worry about facing all the hassles and possible lengthening of average duration for diagnoses.

Can You Drive with a Problematic Auxiliary Battery?

It's not advisable to drive with a failing auxiliary battery. But you may not even notice that the battery has a fault for a while. However, if you do, try to get the issue resolved without delay. Driving with a bad aux unit doesn't pose an immediate risk as long as shifting and handling aren't obviously affected.

Conclusion

You can see the various ways the auxiliary battery is important to your Range Rover Evoque. So you can't take it for granted when it develops a fault, or else the quality of your driving experience will greatly reduce. Also, don't compromise on hiring a technician that's experienced in repairing the unit.

Get a replacement aux unit from a reputable source so that you can get value for your money. You could possibly buy an upgraded aftermarket battery that's stronger and performs better than the one that came with your Evoque.