Calculating Ampere-Hour AH requirement
| Normal Power | 1000 Watts |
| Power Factor | 80 % |
| Inverter Rating | 1000W/80% = 1250 VA |
| Number of Backup Hours | 2 Hours |
| Energy To be Stored | 1000×2=2000Wh |
| Inverter Battery Voltage | 24VDC |
| Battery Amp-Hours | 2000/24=83AH |
| Add @30% AH Margin | 83*1.3=108AH~100AH |
So, for this configuration you need a 1250VA Inverter with 2x12v 100Ah battery bank. Let me explain the calculation,
-
Power Factor: In AC (alternating current), Power = Voltage x Current x Power factor unlike in DC, Wattage = Voltage x Current. Power factor is measure as the cosine of the phase angle between voltage waveform and current waveform. For home use, the power factor will be 0>PF<1. When PF is lower, the efficiency of the system suffers a lot.
-
Battery Voltage: For 1250VA inverter system, the choice of battery bank is 24V instead of 12V. The rationale for this choice is to limit the current from the battery to the inverter unit. If you use a 12V battery bank, at full load there will be a current of 1250/12=104A flowing from the battery to the inverter. You may have noticed the thickness of the battery wire be very high. Despite that the power loss on those wires when the current is 100A, would be much higher than it is with 50A on a 24V system. For a 24V system, the peak current shall be 1250/24=52A. Also, at 100A, with 1m cable between battery and inverter, the impedance should be 0.00001 ohms.
-
AH Margin: Although battery AH rating considers absolutely draining of the battery, we will not be able to do that for normal SMF battery. Meaning, we should not discharge below 10V and likewise should not charge beyond 13.6V per 12V battery. In order for the AH rating to work, we have to apply atleast 20-30% margin.

I have been hit for the same problem when my Altec Lansing 5.1 multimedia system’s remote control broke. In the sense, the remote was functional intermittently. And some time, the key pad mapping got goofed up with + working as – and so on. When I visited my local electronics stores guy, he said the general problem for intermittent remote operation is a conked up crystal that is found inside the remote control unit.
Remote control units work with Infrared light communication between the hand-unit and the multimedia system’s base unit. Commands from the keypad are converted to IR signals, which are received and decoded by the base unit to perform appropriate function. Since IR light is not visible to human eye, one should use a Camera eye to see the IR light. The easiest way is to observe the LED mounted in the front of the hand unit through a mobile camera or any camera that’s in working condition. The cameras bandwidth covers IR and UV apart from the visible spectrum. You will find that the IR led blinks (carrier frequency is 22khz), when you press any button on the remote control unit. If you observe that for some keys the IR led is not flashing or intermittently flashing, you may associate the problem to a faulty crystal in the remote control PCB.
When the remote is opened, you will see a PCB like the one in the picture. The PCB could be plucked out from the casing by hand. You will also see a rubber like buttons which are the actual buttons that you press. The rubber button is placed on the PCB, where the button presses are converted to switching action. Remember, the buttons will have a conducting coating under it, which indeed closes the circuit when the button touches the PCB.
The crystal that comes as a part of the circuitry is shown in the picture. It is otherwise called a ceramic resonator, which is the crucial component of an oscillator circuitry. Crystals are typically used against LC, RC tank circuits for its very high stability feature against temperature and humidity. My remote uses a 455Khz crystal named 




















