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Buyer's Guide

How to choose the right inverter & battery for your home?

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Planning to buy a new inverter or upgrade the old one? Whatever be the reason, it is very important to understand which are  the right inverter and battery for your home.  Want to choose the best configuration? You would need answers to the following questions:-

  • What is your Power requirement?
  • What VA rating will you need basis your requirement?
  • What will be the right battery for your inverter?

 

Let us first understand your Power Requirement

One of the most important thing that you must know before buying an inverter is your “power requirement”. In simple words- what all electrical appliances (like CFL, tube lights, fan, television, computer, refrigerator etc.) you will run at the time of power cut. Power requirement is addition of the power consumed by various electrical appliances.

Suppose you want 3 Fans, 3 Tube lights, 8 LED lights, 1 television & 1 refrigerator to operate at the time of power failure. The power consumed by these items will be total of the power consumed by these individually:

1 Fan – 70 Watts

1 tube light – 40 watts

1 led light – 7 watts

1 led television – 70 watts

1 Refrigerator - 140 Watt

Therefore your total power requirement is (3*70 +3*40 +8* 7 + 1*70+ 1*140) = 596 watts

 

Find the VA rating of the inverter you need

VA stands for Volt ampere rating. It is the voltage and current supplied by the inverter to the equipment. Your appliances need more VA than the power requirement in Watts due to the nature of the devices. The ratio is called Power factor.

Hence Power supplied (or VA rating of inverter) = Power requirement (power consumed by equipment in watts) / Power factor.

Usually at homes, power factor ranges from 0.65 - 0.8, taking 0.7 for the calculations,

Power of inverter (VA) = 596/0.7 = 851 VA

So an inverter with 900 VA will be the right choice for your home

 

Know the battery your inverter needs

The performance of an inverter largely depends on the battery. Battery stores the energy needed to run your appliances during power cut. The next big question is “how much back up will an inverter provide?” or for “how many hours it can run all of your appliances?”. This is determined by battery capacity. It is expressed in Ah (Ampere Hours).

Luminous batteries are available from 60 Ah - 220 Ah, so how will you finalize which one do you need? To find this out let’s do a reverse calculation. Consider that you need a battery that provides back up for 2 hours for running appliances of load 851 VA (596 W).

Battery capacity = Power requirement (in VA) * Back up hours (in hrs) / Battery Voltage (in volts)

For lead acid battery, battery voltage = 12 V.

Battery Capacity = (851 * 2) / 12 = 142 Ah

In reality battery performance degrades with usage, so you are recommended to buy 5-10% higher capacity battery.

Therefore a battery with a capacity of 150 Ah will work for you.

So if you want to run 3 Fans, 3 Tube lights, 8 LED lights 1 television & 1 refrigerator for 2 hours during power failure you would need 900 VA inverter and 150 Ah battery.

Single Battery or Double Battery

Now suppose your power back up requirement is 4 hrs for the same power load.

Battery Capacity required = (851*4) / 12 = 284 Ah ~ 300Ah

Since batteries are available between 60-200Ah, you will need 2 battery of 150Ah (in series) to provide 300 Ah. Two batteries together create 24 V output, hence you need to choose inverter which supports 24V input.

Battery plate type

Lead acid batteries come in flat plates or tubular (rod shaped) plates.

Flat plate batteries come in small height containers, and are suitable for low power cut areas as their designed cycle life is low.

Tubular batteries come in small as well as tall containers, they typically have longer design life, suitable for all areas. Due to the longer life, they are replacing flat plate batteries in inverter battery applications.

Plates should be constructed from highly pure lead alloy with high pressure casting machines to ensure low maintenance and long life.

 

Other Features

When buying you may consider other features such as

  • Warranty: Higher warranty indicates longer life and superior quality. Typically, warranty on batteries range from 12 months to 48 months.
  • Float indicators & vent plugs: Batteries have conveniently placed visible float indicators, so that you don’t miss topping up water when needed. Vent plugs should be designed to ensure that the gas pressure inside the battery is regulated.
  • Terminal Protectors: Batteries should come with terminal protectors to ensure utmost safety to the consumers. These protectors prevent chances of accidental electrical shock.