How To Relocate Your Mustang’s Battery For Improved Handling

Prior to 1920, the early Ford Model T had hand cranks to start. Fortunately for everyone, Ford continued to advance its technology throughout the century, which meant our 2001 SVT Cobra came equipped with a battery and an electric starter. However, this conveniently located battery does bring some complications. You see, our 2001 SVT Cobra is being modified for road course duty. Vehicle dynamics and weight distribution are crucial to the Cobra’s ability to navigate corners. Having a 40-pound battery positioned directly over the left front tire is not optimal. The good news is that we can easily relocate the battery to a more suitable position.

relocate battery

An Optima Yellow Top battery, a kit from Ron Francis Wiring, a hold down bracket from Eddie Motorsports, and a few other components to get this battery swap project done.

Track Side Physics

Before we delve into the literal nuts and bolts of relocating the battery, let’s indulge in a bit of nerding out about the physics behind why we considered moving a battery. The simple answer is weight distribution – but the more intricate explanation involves the concept of moment of inertia. 

For years, drag racers have frequently shifted batteries from the engine compartment to the right rear corner of the trunk. The reason? When they hit the gas at the starting line and weight transfers longitudinally from the front tires to the rear tires, having the battery over the right rear tire aids in traction. This approach is fantastic for drag racing, where the cars move linearly. The advantage of having weight on the drive tire is significant for rear-wheel-drive cars. However, road racing introduces a much more dynamic scenario.

relocate battery

This Eddie Motorsports battery mount (P/N: MS374-96MB) is specifically built for an Optima battery and holds it in place solidly. Here you can see it has been mounted in the right rear seat position.

In road racing, cars not only accelerate, but also brake intensely and execute sharp turns in both directions. Every action the car takes on the track is channeled through the contact patches of its tires. If any of the four tires becomes overburdened, traction is lost and the tires are unable to respond to the driver’s demands. In the case of a stock 2001 SVT Cobra, the hefty battery sits directly over the left front tire.

When the car is on the track and thrown into a right-hand curve, the left front tire bears a substantial load. If the tire is overloaded, it can slide, causing the car to understeer. This approach isn’t the quickest way to navigate a corner. By relocating certain components of the car to achieve a more even distribution of weight across all four wheels, the car’s handling improves, enabling it to navigate corners more swiftly.

relocate battery

The first step to moving the battery was making sure power could still be supplied throughout the chassis where it needs to be. This lug from Ron Francis Wiring allowed power to be distributed to items under the hood.

We decided the trunk was not the optimal position for our battery, so we opted to relocate the battery to the right rear passenger seat location. Placing the battery’s weight here can counterbalance the driver’s weight. Additionally, positioning the battery in the rear seat area will reduce the vehicle’s moment of inertia. Moment of inertia refers to a vehicle’s ability to resist rotation. The farther away heavy components, such as batteries and fuel tanks, are located from the center mass of the vehicle, the more force it takes to rotate the car.. By situating the battery between the front and rear axles, we reduced the Cobra’s moment of inertia, thereby enhancing its handling on the track.

battery relocate

Battery Relocation And Wiring

We added protective sheathing around the positive battery cable which was routed from the lug in the engine compartment all the way to the Optima battery in the passenger area. Starting with a battery relocation kit from Ron Francis Wiring, we had 90-percent of the necessary parts to execute the battery move to an improved location.

We supplemented the kit with extra rubber boots and included a circuit breaker in this project. Additionally, we chose to replace the stock battery with an upgraded Optima Yellow Top battery. These Optima batteries are designed to be mountable in nearly any position, they withstand vibration, and they’re leak-proof. These characteristics make them an ideal choice for a battery installation within a passenger compartment. To facilitate the battery relocation, we obtained long battery cables.

We ran the positive battery cable down the length of the door panel to get from the engine compartment to the rear seat area where the Optima battery was to be mounted. Critics who are familiar with racecar safety might suggest he run the cable down the transmission tunnel to avoid the positive cable being damaged in a side impact on track.

Even though the new Optima battery was destined to be positioned in the right rear passenger seat area, this didn’t negate the requirement to route power from that battery to the engine compartment, where the original stock battery was located. A lengthy positive cable needed to be threaded from the battery to a Ron Francis Wiring lug that we had installed under the hood, enabling power to feed into the stock power distribution and starter wire.

It’s important to note that we still intended for the starter to function. After all, this isn’t a Model T with a hand crank. As for the stock ground wire, which initially connected to the original stock battery, it was simply fastened to the chassis under the hood, and the new Optima battery was grounded to the interior chassis.

In order to attach the terminal ends to the long positive battery cable we used a handy $40 Amazon crimper to get the cables just the right length. Believe it or not, battery cable of this gauge is heavy; on a racecar weight savings is key, so ensuring the cable was no longer than necessary was important on this project.

Battery And Bracket

Given that the battery was to be positioned within the passenger compartment, ensuring the battery hold-down mechanism was sufficient became critical. This precaution is aimed at preventing the battery from becoming dislodged during a collision and potentially endangering the driver.

We opted to employ an Eddie Motorsports mount designed to secure the battery firmly in place. Notably, this mount features robust hardware that meets race safety scrutineering standards. Moreover, the thoughtfully designed kit streamlined the installation process in the rear seat area. As this car is specifically intended for track use, the rear seat has already been removed as part of weight-saving measures.

These red rubber boots were used on each terminal end of the new positive cable to ensure the positive cable won’t contact anything causing an electrical arc. This is also required by most racing tech inspectors

After appropriately shortening the cables to the correct lengths, we affixed rubber boots to the ends of each cable. This measure aimed to prevent the positive cable from making inadvertent contact with any components, which could potentially lead to blowing a fuse or even worse consequences.

Speaking of fuses, we made the decision not to incorporate a fuse into this line; instead, we opted for a heavy-duty circuit breaker. This choice holds distinct advantages. Should an unforeseen circumstance cause the circuit to trip, the circuit breaker will promptly disconnect the power from the battery, providing an immediate safety feature. Furthermore, in the event of such an occurrence, rather than requiring a replacement fuse, you can simply press a button to reset the breaker. Another benefit is that if you ever need to disconnect the battery for maintenance, prevent battery drain during prolonged storage, or employ it as an anti-theft measure, this can be swiftly achieved using the circuit breaker.

This handy circuit breaker was mounted in the area of the right rear seat where the driver can reach it to reset it easily. You can see the new positive cable has been mounted to both sides of the breaker and the protective rubber boots are in place.

The Optima Yellow Top battery provided the choice of connecting the battery cables either on the side or on the top. We opted for the side mount option. We initiated the connection by attaching the positive cable from the newly added circuit breaker. Then, we grounded the battery’s negative terminal to the floor pan. The Eddie Motorsports mount performed flawlessly, securely holding the Optima battery in position. We meticulously attended to the routing of the new positive cable, making sure to incorporate additional sheathing anywhere that prolonged vibration might pose an issue, particularly as the cable traversed the bulkhead.

Here you can see the Optima battery is safely held down by the Eddie Motorsports mount in the rear seat, it has been grounded to the chassis and the positive cable ends are covered up for safety. Project done!

A Handling Improvement With A Simple Install

The entire project proved to be relatively straightforward, and thanks to the optimal (pun intended?) battery placement, it’s expected to result in an improved handling Cobra. When we turned on the ignition, the car started up as it should. Now, the only task remaining is to return to the track and evaluate whether the Cobra will perform as expected.

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Rob Krider

Rob Krider will race absolutely anything. He is a multi-national champion racing driver and is also the author of the novel, Cadet Blues.
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