If you have a heartbeat, then there is something in this article that you need to know. If you’re involved with surveillance or other public safety activities, then you need to know all of it! Knowing which battery is right for the job, and how to use that battery is critical for the missions you conduct.
Over the past twenty years of providing surveillance technology to law enforcement and military, I’ve collected a lot of questions and old wives’ tales about battery power for surveillance. In this article, I’ll answer and debunk the most frequently heard.
Will a fuse protect my gear from too much voltage?
Nope…. not whatsoever! So, you might ask what then is the job of a fuse. In simple terms, the job of a fuse is to prevent fires. For a further explanation, fuses protect against too much current draw (amperage) which is typically caused due to equipment failure or shorts in wiring. If you experience a blown fuse, it can be a fluke occurrence but it most likely means something is terribly wrong with your surveillance equipment.
Can I use a car battery for surveillance?
Yes and no. Yes, you can use a car battery for surveillance, but there are a few catches. First, if you're using a car battery and consequently the power from the cars charging system, you run the risk of ruining your surveillance gear with too much voltage. To correct that, at a minimum, you’ll need to put a DC to DC converter in between the gear and the car's power system, which will keep the voltage at a constant 12 volts.
Another peril with the use car power for surveillance gear is ending up with a dead car battery from using in a way the car battery isn’t designed for and simply draining it. A way to solve these two issues, and the earlier mentioned overvoltage issue, is to use an auxiliary battery and a battery isolator. With this combo, your surveillance gear will benefit from having its own power, plus the auxiliary battery will be charged when the vehicle is running.
Will too big of a battery overpower my device?
Nope, impossible! The physical size of a battery is only an indication of how much juice (amperage) it has to offer over a given period of time….and is not an indication of voltage. As an example, if you have a small 12-volt surveillance camera that you typically operate using 8 x AA batteries (12 volts), then it will work just fine on a giant 12-volt marine battery, just a heck of a lot longer!
How do I determine battery run time?
This is simple, and for a general estimation, you just need to know two basic things, what is the current draw of the device (amps), and what is the amp-hour rating of the battery. For an example, let’s take a common covert pinhole camera which typically draws 100mA (or expressed 0.1 amps), and a common SLA (sealed lead-acid) battery that offers 12aH (12 amps for one hour, or expressed 12,000mAh for one hour). To calculate run time, just divide the battery amp hour rating by the current draw, in this case, 12,000mAh / 100mA = 120 hours.
For additional assurance of predicted run time, shave off ten-percent of the runtime. This will help accommodate for any battery inefficiencies and temperature changes which do affect battery performance.
Do voltage readings indicate battery charge level?
Somewhat. A common technique for folks wishing to check charge level on a battery is to use a voltmeter. Using that technique, when the reading returns e.g. as 12 volts on a 12-volt battery, the typical assumption is that the battery fully charged. In reality, though, the battery may be completely dead.
To check charge, the battery must be tested under load. The easy way to do this is to use a…you guessed it, a battery tester. However, if all you have is a multimeter to can get a reasonably good idea by checking battery voltage when your surveillance equipment is drawing power from the battery. Using the example of a 12-volt battery, if it reads 12 volts when surveillance gear is connected...then there is a nearly full charge.
What type of battery is best?
It depends on the application, different battery technologies will produce differing results with primary factors being current demand and temperature. For a basic overview
Ideal for body worn or other applications to where size and weight must be as little as possible. However, lithium is intolerant of temperature extremes and during such conditions, will self-discharge.
SLA (Sealed Lead Acid)
Recommended for any application that requires long shelf-life. A great example is field applications to where the surveillance equipment may remain on standby for months or even years. SLA batteries are very tolerant of temperature swings, however, they are much heavier and bigger than lithium.
Marine batteries are a great value, in that they offer a high current-capacity for money spent. They are excellent for vehicle-borne surveillance and serving as an auxiliary battery. Because of the size and weight, they are difficult to use in most other applications.
Due to the growing popularity of lithium technology, alkaline batteries have pretty much taken a back seat. But, alkaline cells have a tremendous shelf life that can be beyond ten years. This amazing shelf life makes them perfect for bugs that may remain hidden for years and remotely engaged as needed.
Can I use battery powered surveillance equipment while the battery is being charged?
Yes, so long as the charger is rated to deliver enough power to the equipment being used and charge the battery simultaneously. As an example, if the surveillance system requires 2 amps, and a 4 amp charger is being used…. then it’s perfectly fine.
Should I fully drain my battery before charging?
These days, no. This concern stems from nickel-cadmium batteries which were popular in the 90’s and early 2000’s. Nickel-cadmium were very prone to develop a memory and to mitigate the issue, users were forced to completely discharge the batteries prior to a charge. Thankfully, popular batteries today such as SLA and lithium do not suffer from the same issue.
Thanks for reading, and I sincerely hope this article has been of assistance to you. Please feel free to contact with comments. I'm easy to reach via email
or by phone at 1-855-778-6565.