Replies to post #94679 on World Surveillance Group Inc (fka WSGI)

[CHECKMATE 1]

Mide By using what are called "inverters", 12 volts can be converted to 110, 220 etc etc .CHECKMATE

[ken w]

mide, the issue is the efficiency of the equipment in terms of electrical draw. All AC or DC power can be converted one to the other. If the equipment is efficient, they will draw little amps to run. During the day, enough amps are supplied by the solar cells and at night stored amps are used, even though some solar cells can generate power from moonlight, light being the operative word. So, if the equiptment draws amps efficiently and the charging systems are constantly supplying power as well as putting stored energy away for night operations, the airship could theoritically fly and operate for long periods of time. Voltage is only 1 part of the measure of storage requirements - it's the amps required that are the most important measure. So, if a radio puts out 48V but only uses 1/2 amp, that's the measure of the storage system required for continual operations. The more efficient the better. V=IR (V=voltage; I=amps; R=resistance)If R is low(efficient) and I is small, then the V required is calculated. Anyway, that's how I see it. Anyone else jump in here.

[trunkmonk]

mide, sure you can invert DC to AC but that is not efficient, maybe 85%, much power loss in the form of heat. DC motors have been around for a long time, fact is, cars have DC motors, no inversion. 12v battery in series with another is 24v, one more in series makes 36v, and so on and so on. dc motors are very efficient, very high torgue dynamo's where you get 100 torque at o rpm. trains and elevators have DC motors in them for years, very powerful at low speed any can have RPMs limited only by inertia breaking the rotor to pieces.

[p944na]

Mide - it is a matter of energy consumed vs energy available. if there is sufficient energy available over and above what all the electronics are consuming, then you are good to go. Voltages can be converted up or down, from ac to dc, using various devices. the down side is energy loss during the conversion - efficiency.

For your 48v 1.2 amps case, that unit is consuming P=VI = 48x1.2 = 57.6 watts of power. As long as the system can supply the approx 60 watts of power (plus conversion loss) then A ok. (Note - a 60 watt light bulb has same power.)

[Skyvision]

Mide

Is the Hotzone 48 volts input or output?

48 volts DC input (power rqmnt) makes sense, and can easiily be accomplished with (4) 12 volt cells connected in series (or 8 six volt cells). Being that it only draws 1.2 amps, you don't need car battery sized cells (unless you intend to operate all night). Remember, this is only for the mission package (Hotzone), not propulsion (different problem)..

Bottom line - the cells can be arranged to allow a 12 volt charging system to devlop higher operating voltages (48v in this case). If I recall my EE correctly power (watts) = volts X amps. So we're talking 48 * 1.2 = 57.6 Watts....roughly 60 watts (equivalent a single AC light bulb).

It makes no sense whatsoever to involve ac inverters, unless there is a hard requirement for AC (unlikely IMO).

[nerd86]

moide the battery cells are configured to deliver ~90VDC. The AC average power factor from DC is .707. So after inversion divide 90VDC by .707 and to arrive at 127+ volts AC. AC can be factored to any value using transformers and returened to DC. This is a lossy way of handling a local power need but would support existing equipment without modification.