Solving a Tesla Police Patrol Car’s Power Failures with the Patrol EV Auxiliary Power System

At Patrol EV, we’re passionate about helping law enforcement agencies transition their fleets to sustainable, high-performance vehicles. But going electric requires specialized knowledge, particularly when it comes to integrating the power-hungry systems that modern patrol vehicles depend on.  We were contacted by a police department facing serious issues with their Tesla patrol vehicles. Their experience highlights exactly why it’s important to work with Patrol EV, a specialized EV upfitter who truly understands Tesla vehicles—Read on to learn how our Auxiliary Power System (APS) solves these unique challenges.

The Problem: Intermittent Dead Battery Failures on Patrol Teslas

The department had already invested in upfitting their Tesla with lights, sirens, radio, radar, and other equipment through a traditional local upfitter. While the add-on gear technically worked, the patrol car started experiencing troubling, mission-critical failures.  Most alarmingly, the vehicle would occasionally die completely. When the Tesla low-voltage system is drained, it’s not like a gas car with a dead battery that you can jump easily and get going again. Instead, the vehicle becomes completely unresponsive:

• Doors won't open
• Touchscreen stays black
• No power to lights or radios
• Critically, the car will not even accept a charge

At that point, the vehicle is effectively bricked until a special jump-start procedure is performed by Tesla service personnel. For a police department that relies on that car for patrol duty, this isn’t just an inconvenience—it’s a major operational risk.

Diagnosing the Root Cause

When we were called in to help, our first step was a deep diagnostic review using Tesla’s onboard systems. The car’s logs told the whole story:

• Numerous error codes and warnings showed that upfit components were drawing too much power from low voltage taps made on vehicle circuits which are unable to support the power load.
• The original installer had tapped power in ways that weren’t designed to support constant, heavy-duty police equipment loads.
• This placed strain on the Tesla’s low-voltage battery and power supply system, which isn’t sized for any kind of continuous auxiliary low voltage demand.

Over time, that strain degraded system stability—leading to the total shutdowns the department was seeing in the field.

Why Police Upfits Are Especially Challenging for Teslas

Police patrol cars aren’t ordinary consumer vehicles. Even at idle, they often need to run:

• Emergency lights
• Radios and dispatch computers
• Radar or license plate readers
• Camera systems and DVRs

All of these have significant electrical demands that don’t go away just because the car is parked.  On traditional gas-powered patrol cars, that demand is usually covered by the alternator and a beefed-up auxiliary battery. With Teslas and other EVs, the integration needs to be done properly to avoid overloading the low-voltage system.

Our Solution: Patrol EV’s Auxiliary Power System (APS)

At Patrol EV, we specialize in EV upfits. That means we design our integrations specifically around Tesla’s electrical architecture, using Tesla-approved methods.  For this police department, we removed the problematic wiring taps, installed our Auxiliary Power System (APS), and re-routed all auxiliary power though the Patrol EV APS.

 

Patrol EV Auxiliary Power System (APS) provides:

• A dedicated power source sized for high-demand police electronics
• Proper integration that isolates auxiliary loads from Tesla’s critical low-voltage system and will continue to operate properly regardless of any future Tesla OTA updates
• Tesla-approved connection points, avoiding warranty and service issues
• Stable, reliable operation even with lights, radios, and cameras running for hours
• Safe wiring, requiring no 'high voltage' training or certification - no need to 'call us to come reprogram' things after Tesla makes a change or OTA update or the municipality wants to modify components on the build.

 

Once installed, the Patrol EV APS eliminated the random shutdowns and low-voltage battery failures entirely. The department reported zero issues after our retrofit. Their Tesla was back on patrol, doing what it was supposed to do—serving the community reliably.

Why It Matters

EVs are a future of policing. They’re quiet, quick, and far cheaper to operate over time. But they’re not just “plug and play” when it comes to police upfitting.  Police fleet managers need to know that their installers truly understand how to work with these vehicles.

If the integration is done wrong, departments can end up with:

• Dead / bricked cars that won’t respond
• Costly downtime waiting for Tesla or Upfitter service calls
• Voided vehicle warranties and costly repairs
• Risk of damage or fires resulting from hacking into the high voltage system 
• Frustrated officers and supervisors

At Patrol EV, we want to help agencies avoid these headaches altogether.

How We Can Help

If you’re running Tesla patrol vehicles—or considering adding them to your fleet—we’re here to help.

• We specialize in Tesla (and Rivian, and other EVs) police upfits
• We design systems that respect Tesla’s engineering
• We provide auxiliary power solutions which are safe from OTA obsolesence 
• We allow 'after upfitting' access to the APS so departments can add components and safely make the connections themselves 
• We do not hack the high voltage power system with DC converters
• We have been upgrading Tesla vehicles for longer than anyone and know how to work with, rather than around, their systems

 

Our mission is to help police departments modernize without compromising reliability or safety.  If you’re facing issues with your Tesla police vehicles—or if you want to make sure you don’t—please reach out to us.

Contact Patrol EV