POWER SUPPLY SYSTEMS

Using 120 VAC / 60 HZ or 220 VAC / 50 HZ is a logical choice when various head end components (recorders, multiplexers, monitors etc.) require that power and can be protected from ambient weather.

Problems: Power outages, future field portability, still need 12 VDC for most cameras., dangerous voltage & current are present etc.

WET lead / sulfuric acid deep discharge batteries are cheapest source of field power.

Problems: Heavy, burns from sulfuric acid spills, must be carried, charged & discharged in upright position. Should always be transported in a battery box.

SAFETY NOTE: If you use wet cells, always keep on hand a 2 liter bottle of water for eye irrigation and another 2 liter bottle of water with 6 to 10 tablespoons of baking soda dissolved in it to neutralize acid on skin and clothing.

Sealed Lead Acid, Absorbed Glass Mat and GEL cells again are relatively cheap and can be carried, charged & discharged any position. Available in many different capacities.

Problem: More expensive than wet cells but a lot cheaper if you have an accident in the field with a wet cell.

Photovoltaic systems are a good choice for systems that are only occasionally moved and intended for multi-season use. Smaller panels can extend the run time between battery changeouts. As the cost of panels continues to drop and video systems become more energy efficient, they deserve serious consideration.

Problems: Must be sized to the location and environment where it is deployed. Batteries required to store the energy. High wind areas require proper mounting and snow cover greatly reduces output. High initial cost and usually bulky to transport. Difficult to conceal from casual observers.

Immersed water turbines mounted in a stream with 18 inches (0.5 m) of water depth and a velocity of 3 to 4.4 ft/sec (0.9 to 1.2 m/sec) is sufficient to run most video systems.

Problems: Seasonal fluctuations in water flow. Debris in stream. Distance to recorder system must be relatively short. Batteries required to store the energy. Power diverter required to bleed off energy when batteries are fully charged

Pipe fed turbine with 50 ft. (15 m)of head at 3 gallons / minute (11 liters/ minute) is sufficient to run most video systems.

Problems: Seasonal fluctuations in water flow. Distance to recorder system must be relatively short. Batteries required to store the energy. Power diverter required to bleed off energy when batteries are fully charged

Wind turbines usually are designed for higher current requirements. If a central charging station were required for multiple field units, this might be a good choice.

Problems: Fluctuations in wind velocity. Distance to recorder system must be relatively short. Batteries required to store the energy. Power diverter required to bleed off energy when batteries are fully charged. High wind areas require proper mounting. High initial cost and usually bulky to transport. Difficult to conceal from casual observers. May be hazardous to birds / bats. Movement and noise may disturb subjects.

Lithium Ion batteries continue to drop in cost and are especially useful for systems that must be transported by air or in difficult terrain by back. At 1/3 the weight of a SLA / AGM battery for the same amount of energy storage they deserve serious consideration.

Problems: Four to five times the cost of an SLA / AGM battery. Require special charging systems and battery management boards for working lifetimes of more than 400 cycles.

On first look, a fuel cell system which require methanol as an energy source, appears to be a no brainer. A forty hour run of a video system requiring 25 watts (1 KWH) of energy (approx. 2 amps @ 12 VDC) uses approximately 2.2 pounds (1 KG (1.3 liters)) of methanol. GREAT!! A five day run (120 hours) consumes 9 pounds ((4 KG (4 liters)) of methanol. GREAT!! The fuel cell system(without protective weatherproof overcase - see below) weighs 13 pounds (6 KG), the fuel cartridge weighs 9 pounds (4 KG) and a 12 volt/ 12 Amp-hour battery (required)weighs 9 pounds (4 KG). Total is 31 pounds (14 KG) GREAT!! Your checking account is lighter by $5000.00 to $6000.00 NOT SO GREAT!! MIL-SPEC systems are available but they cost a lot more.

Problems: Basic system is not ambient weather protected so a protective overcase with stabilizer brackets is required. System can be tilted +/- 20˚ and still run, at +/- 45˚ the system will start to shut down, if laid on its side the system will not run at all. Operating temperatures are -4 to +104˚ F (-20 to +40˚ C). At +105˚ F (+41˚ C) the system shuts down and will not charge the battery. Temperatures above +149˚ F (+65˚ C) are critical as methanol starts to boil. Low temperature system can operate down to -31˚F(-35˚C) and require a low temperature battery. Warranty may be voided if manufacture's brand of methanol not used as

Stand alone generator systems are usually not recommended as they produce far more power than required for even a very large video system. A more practical approach is to use a generator with the proper charge controller to charge a group of batteries ( which could be deployed to various systems over many days) in just a few hours.

Problems: Noise. Fuel transport hazards. Low temperature operations may require propane fueled generators.

When systems are operated out of their normal ranges (say arctic cold or desert heat), special consideration must be given to the systems chosen and the level of integration required for reliable operation. As a general rule, you can expect batteries to have lower discharge performance at low temperatures and that batteries and electronic equipment will have shortened working lifetimes at high temperatures. Much discussion is required.