> For the complete documentation index, see [llms.txt](https://wiki.malamaker.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.malamaker.org/projects/hobby/death-racer/kill-switch-relay-mod-headshot-trigger.md).

# Kill Switch Relay Mod (Headshot Trigger)

### Overview

This page outlines a **reliable relay-based solution** for implementing the classic **headshot kill switch** used in Death Racer battles. When the racer figure's head is knocked off, a switch is released, triggering a shutdown of the RC receiver and rendering the vehicle inoperable — the battle is over.

> 🎯 **Gameplay Objective:** Knock off the opponent’s head to kill their vehicle.

The **"head = kill"** mechanic is standard in Death Racer builds. However, the typical method — routing battery power **directly through a mechanical switch** — has proven unreliable and **prone to burnout**, especially with 15–20 amp toggle switches.

This guide introduces the **relay mod fix**, as discussed in theory by Jeremy (M86 Toys) on [LeeMerie3D’s May 20, 2025 stream](https://www.youtube.com/live/wEGIBDx9eeo?si=O14ZI3in3b7Ro6eR\&t=817), and will be implemented in upcoming streams using this documentation.

***

### The Problem with Direct Power Switching

* Builders often run the **main battery voltage directly through the switch**
* Most toggle or magnetic switches used are **rated 15–20 amps,** under rated for the potential amp load.
* Death Racer power setups can **spike higher**, leading to **switch failure, overheating, or fire risk.** Spikes can happen when resistance is applied to motors driving the death racer.
* This puts the **entire receiver system at risk** and leads to inconsistent kills

***

### The Solution: Relay-Controlled Kill Switch

Instead of routing full power through a switch, this method uses a **low-power switch** to control a **relay**, which handles the high current load.

#### How It Works:

* A **normally-open switch** is placed under the Death Racer’s head
* When the head is attached, the switch closes and activates the **relay**
* The **relay connects the battery to the RC receiver**
* When the head is knocked off, the switch opens → the relay cuts power → the vehicle dies

> ⚠️ This isolates the mechanical switch from the full battery current and **dramatically increases reliability and safety**

***

### Featured on Stream

Jeremy (LeeMerie3D) explained this fix on [LeeMerie3D’s livestream – May 20, 2025 (13:37 mark)](https://www.youtube.com/live/wEGIBDx9eeo?si=O14ZI3in3b7Ro6eR\&t=817). Watch the live comments by "MalaMaker" explaining this addition.

***

### Parts List

* 1x Relay module (DC 12V automotive relay, 40amp recommended)
* 1x Normally-open switch (original switch designated for the death racers)
* Wire, connectors, heat shrink

***

### Wiring Concept

```
       Battery (+) ───> Relay ───> RC Receiver (+)
                          ▲
Battery (+) ───> NO Switch (Head-Mounted) ───> Battery (-)
```

* Switch is **closed** when head is on — relay stays active — receiver has power
* Switch is **open** when head is knocked off — relay cuts — vehicle is dead

***

### Mounting Tips

* Mount the switch in a way that the figure’s head holds it closed
* Use a press-fit, snap-in, or magnet-based head that reliably pops off on impact
* Secure the relay in a protected spot near the battery

***

### Safety Benefits

* Keeps high current off fragile switches
* Prevents melted switches or mid-match failures
* Increases reliability and reproducibility of kills
* Makes builds tournament-ready

***

### In Development

The final wiring demo, mounting technique, and live test of this relay-based system will be featured in an upcoming LeeMerie3D stream. This wiki page will be updated with:

* Video tutorials
* STL relay mounts
* Printable wiring diagrams
* Troubleshooting guide

***

### Want to Help?

If you’ve built this mod successfully or have refinements, consider contributing back to this page or submitting photos, diagrams, or footage of your working rig!