Often a deciding factor between drama and mission success is how well vehicle power has been provisioned for surveillance gear. In this article, I’ll share my lessons learned and if applied, I assure you that it will aid in mission success.
Who Needs This Information?
This article is aimed at missions lasting longer than a couple of hours, or those frequent in nature. Some great examples are buy cars, drop cars, and bait vehicles for BMV and auto theft. For short-term ops, there will be useful information and you should certainly bookmark this article for future use.
Plan and Do No Harm
Wiring a car for surveillance is far different than the routine jobs they get in the radio-shop, you’re likely dealing with some odd car from the seizure lot, an informant, or maybe an insurance company donation. Either way, take your time to inspect the vehicle to determine power sources and best routes to run cabling. The plan should avoid any comprises of the vehicle safety.
The following are topics that are presented in a sequential fashion and can serve as a checklist when you're developing the cars wiring plan and shopping list.
Where To Get Power
In getting power for your covert surveillance gear, you should have some goals in mind, find a source that is HOT (provides constant power, even when vehicle is off), provides enough amperage to meet the demands of your equipment, can be concealed upon a cursory inspection, and does not interfere with today’s computer monitored circuits. In order, here are the spots that I prefer:
Main Feed to Fuse Panel (Pre Fuse Box)
Every vehicle has a fuse panel, and most fuse panels have an accessible main feed. This location tops my list due to its relatively unlimited amperage capability, ease of adding on a crimp ring thanks to the smaller bolt size, ease of concealment, less mess compared to a battery, and the strong likelihood that I won’t interfere with other circuitry.
Additionally, the main feed for a fuse panel is typically protected by a limiter fuse. So should you do something terribly wrong later in your wiring, the limiter may help to prevent a vehicle fire. I do need to emphasize though, not all vehicles have a limiter fuse and even the ones that do, they may not help due to an extremely high amp rating.
Battery
The second-best power tap location, in my opinion, is the battery itself. At the battery, you have some of the same benefits as the main feed to the fuse panel. However, there is zero limiter protection at this point, it may be more difficult to conceal your power tap, and you may have to manage the nasty corrosion common to old batteries.
For obtaining power directly from vehicle batteries the automotive-aftermarket industry has created a plethora of accessories that make the job clean, neat and easy. Usually, you can find these taps for around $5 to $10 at your local auto parts store or stereo shop.
A Fuse Panel Circuit (Post Fuse Box)
I’m not a big fan of tapping power from a fuse panel circuit, although I have been forced to do so for the sake of time. If you find yourself in this position, you need to pick a circuit that has two features, is the least critical to safe vehicle operation and has a great potential for excess amperage.
No matter what fuse panel circuit you choose, you may run into a couple of issues. Increasingly, the biggest one is creating a fault in the vehicles computer due to the additional current draw and change in resistance from the newly added circuit. Another common issue is electrical noise, which can leave your evidence looking and sounding horrible.
Backside of Power Outlet
Very low on my list, but still, a decent place to obtain power is the back side of a power outlet (for guys my age, the cigarette lighter socket). Most of these outlets are fairly easy to get to, and most are unmonitored by the vehicle computer. Although this location may be easy to get to, it may be tough to route your wiring away from it and keep it concealed. Additionally, another possible downside is blowing the fuse if the outlet is used by a high current item (air pump, light), in combination with your surveillance equipment.
Fuses
When adding surveillance equipment to vehicles, treat cars as hostile environments. When cars are moving, body parts, wiring, and contents shift, flex, bounce around and sometimes pinch power wires. So don’t learn that lesson the hard way, add fuses! As a rule, I add a fuse on every circuit and sub-circuit that I create. For instance, very close to wherever I tapped power, I add a fuse. I also add a fuse to any branches off of that newly created circuit. As implied, the fuse should be located as close as possible to the power source, and/or branch. Having a fuse right next to a circuit endpoint does no good at all.
I’m often get asked if fuses protect surveillance equipment from overvoltage. This is a legitimate question, but the answer is no. Fuses can pass literally thousands of volts without blowing. Fuse's sole purpose in life is to prevent fires caused by a short circuit and equipment failure which both create an excessive current draw.
When it comes to fuse sizes (amp rating – physical size doesn’t matter), it should be as small as possible. For instance, if your surveillance equipment in total draws 7 amps on average, then use a 10 amp fuse.
Main Power Cable And Where to Run It
Just like fuses, you need to get the right cable for the job. In the case of power cable, physical size does matter. The bigger the cable, the more amperage it can handle and the less voltage drop you’ll experience. For most jobs, I typically use a 12 gauge cable as the main power line. A 12 gauge wire is still small enough that it can be routed easily, and has mere 0.5-volt drop over 20 feet when the surveillance equipment demand is 3 amps…in other words, its great for ninety-five percent of installs. If you need bigger gauge wire than 12, but can’t find locally, you can always double-up and run two main power lines to increase your amperage capacity, and decrease your voltage drop.
If the install vehicle is American, running the power cable is typically easy. Most American vehicles have both power resources and cable pathways, placed on the driver’s side of the vehicle. Most pathways have ample room for additional cables as shown in these pictures. With simple tools, and sometimes by hand, panels can be lifted to expose the cable pathways.
No matter where you run power cables, make sure they are fastened from movement and are protected against abrasion from normal vehicle operations. Depending upon routing, items that I use to manage the cables are zip ties, cord loom, rubber grommets (must have for drilling through the firewall), and adhesive cable tie mounts.
Concerning cable runs, of course, a destination is needed. For my installs, that destination becomes the hub of all things power and surveillance. That destination varies greatly depending upon the vehicle, but a great default in a car is the spare tire well. The spare then finds a new home in the trunk or is completely removed from the car. With most newer trucks being extended or four doors, I almost always use the voids underneath the rear seat as a place to mount my surveillance gear.
Auxiliary Battery
Some view auxiliary (aux) batteries as an optional piece of equipment, but there are some tremendous selling points in installing one. First and foremost, if installed correctly the auxiliary battery will be the surveillance equipment power source, and it will eliminate the dreaded problem of dead starting batteries. Additionally, the aux battery can act as a giant capacitor to help filter out electrical noises, and eliminate ground loop issues that are very common to all vehicles when adding new circuits.
For auxiliary battery types, I highly recommend an SLA (sealed lead acid) battery or a marine battery. Both of these batteries have a low self-discharge rate, are temperature tolerant, and are designed to offer low amperage outputs over long periods of time. Regardless of battery type, be sure to mount it in a solid position and if possible, give it some type of cushion against vibration. In terms of battery size, get the biggest battery that space and budget will afford.
BATTERY ISOLATOR
If you opt for an aux battery, a must-have piece of equipment is a battery isolator. The isolator serves a couple of purposes, prevents the aux battery being discharged from non-surveillance equipment e.g. phone charges left plugged in, and increases stealth. Concerning stealth, without an isolator, if the starting battery is removed for any reason and the car still works…it will raise tremendous suspicion by the automotive tech, and your surveillance equipment will be discovered.
A battery isolator can be as simple as a common diode. Diodes allow for one-way power flow, so the aux battery can be charged by the vehicle, but not provide any power back to the vehicle's system. However, I’m a bigger fan of buying a purpose-built battery isolator which can be easily obtained at any RV (recreational vehicle) store. The battery isolator that I’ve used most often is the WIRTHCO brand unit which also provides battery overcharge protection.
Distribution
With the circuit flow, after you’ve installed an aux battery and isolator, I recommend using a power distribution terminal. My absolutely favorite is again a WIRTHCO brand product, they make a power distribution block with two very important features, fuse port for each sub-circuit, and an LED indicator for each channel that illuminates when a fuse is blown. The WIRTHCO block also makes the job clean and neat.
Get a Solid Ground
Last, but certainly not least in importance, is a good solid chassis ground. The best wiring job is absolutely for naught if you don’t get a good ground. Fortunately, wherever you made your power and surveillance hub at, you likely have some excellent grounding points. To be absolutely certain I get a good ground, I typically drill a hole in the frame or body so that I can hit fresh metal. I fasten the ground using a stainless steel screw, and if the grounding point is a body part, I use sealant to eliminate weather ingress.
Thanks for reading, I certainly hope this article is or will be of assistance to you. It's my personal mission in life to assist law enforcement in leveraging surveillance technology. So if I can help you further, please feel free to contact me. Also, very important, if you have something to add to the article, please post your comment below.
Best regards,
Jake Lahmann