Whenever someone is buying an inverter battery for their home, office, shop, or for any use for that matter. The biggest concern is, how long will the battery last?
The backup time of the battery varies from battery to battery and how much load it would be carrying. Usually, you can expect your inverter battery to last anywhere from 3 to 8 hours when it is fully charged depending upon the capacity of the battery and your load requirements.
In this article, We will help you calculate the backup time using an easy-to-use calculator and a formula.
HOW LONG WILL INVERTER BATTERY LAST [RUN TIME] – USE THIS SIMPLE CALCULATOR
The following calculator should be able to give you an idea of what to expect for your particular application. Using the information below, fill in the fields with details about your battery and see how much backup time you can expect out of it! In case you find any difficulty in calculating, skip this section and proceed to the next section.
Note: Consider the above calculation is an approximation because we can't exactly know how much an old fan or tv consumes or whether your inverter is working upto its efficiency etc., You can consider -10% to -15% buffer to above result.
HOW TO CALCULATE INVERTER BATTERY BACKUP TIME [RUN TIME] – THE FORMULA
Have some difficulty in calculating the inverter battery backup time?
Don't worry. Follow the steps and examples provided below to help you calculate your inverter battery backup time.
1. KNOW THE BATTERY CAPACITY:
Battery capacity determines how fast current flows and is measured in Ampere hours. Higher Ampere hour means electricity flowing quickly and delivering more power to appliances. One can find the battery capacity on the battery user manual or product description or on the face of the battery.
2. FIND THE INPUT VOLTAGE OF BATTERY:
The voltage of the battery is the unit of potentiality in your battery and is measured in volts. The higher voltage, the more current flows through the battery and power the appliances. In general, every home Inverter battery comes with 12v. You may find this detail in the user manual.
3. CALCULATE THE CURRENT LOAD(WATT) REQUIREMENT:
Load is the amount of energy required per hour for appliances connected to an inverter and is measured in watts. The watt that each appliance uses is usually mentioned in the package of the appliance. Use our simple load calculator to calculate the load.
Note: Calculate the load requirement of only those appliances which you have connected to the inverter or planning to use during power cuts by connecting to an inverter.
4. CHECK THE EFFICIENCY OF BATTERY:
Battery efficiency is the amount of energy you get from the battery for consumption relative to the amount of energy you input. Some amount of loss is unavoidable during the process of energy discharge. Efficiency % varies from battery to battery, which you can find on the product catalog or can enquire with your manufacturer. In general, One can expect an efficiency of 80% i.e 0.8 from top battery brands like Luminous, Exide, Amaron.
5. CALCULATE THE BACK UP TIME[RUN TIME]:
Backup Time (in hours) = Battery Capacity (in Ah) x Input Voltage (V) x Efficiency %(n) / Total Load (In Watts)
To understand this formula, let's assume that you have an inverter battery with 150AH of capacity, 12 V of input voltage, 80% discharge Efficiency and you have 2 tube lights of 40 watts, 2 fans of 75 watts, and 1 wifi router of 20 watts that is working on this battery. How long will it last in this case? Let's calculate:
Let's first figure out what the total load per hour is:
- 2 Tube lights = 40 x 2 = 80 Watts
- 2 Fans = 75 x 2 = 150 Watts
- 1 Wifi Router = 1 x 20 Watts
The total load, in this case, is, 250 Watts.
Now, let's put these values in our formula:
Backup Time (in hours) = 150 x 12 x 0.8 / 250 = 5.76 Hours
So, your 150 AH inverter battery is expected to provide 5.76 hours in this particular case.
DOES THE SMALLER OR LARGER CAPACITY OF THE BATTERY MAKE A DIFFERENCE?
Obviously, it would make a huge difference. Here are calculations of a smaller and a larger capacity of batteries:
If the capacity would've been, 100Ah:
Backup Time (in hours) = 100 x 12 x 0.8 / 250 = 3.84 hours
So, with a 100 AH battery, We would've got a backup of just 3.84 hours.
If the capacity would've been, 220Ah:
Backup Time (in hours) = 220 x 12 x 0.8/ 250 = 8.448
With 220 AH battery, We would've got a backup of 8.448 hours, which is much more.
So, you can certainly see that battery's capacity whether it is 100, 120, 135, 150, 200, 220, 240 Ah plays a huge role in how much backup you'll have. The more the capacity, the more backup time you'll get.
BACKUP TIME TABLE – CAPACITY VS LOAD – FOR QUICK REFERENCE:
We have created a Capacity vs load comparison table for your ready reference to find how long your battery lasts. Consider going for such capacity, which can give min 3 hours of backup time at a given load.
|CAPACITY VS LOAD||100 WATT||200 WATT||300 WATT||400 WATT||500 WATT||600 WATT||700 WATT|
|80 AH||7.68 Hours||4.08 Hours||2.72 Hours||2.04 Hours||1.64 Hours||1.36 Hours||1.16 Hours|
|100 AH||9.6 Hours||4.8 Hours||3.2 Hours||2.4 Hours||1.92 Hours||1.6 Hours||1.37 Hours|
|120 AH||11.52 Hours||5.76 Hours||3.84 Hours||2.88 Hours||2.3 Hours||1.92 Hours||1.65 Hours|
|135 AH||12.96 Hours||6.48 Hours||4.32 Hours||3.24 Hours||2.6 Hours||2.16 Hours||1.85 Hours|
|150 AH||14.4 Hours||7.2 Hours||4.8 Hours||3.6 Hours||2.88 Hours||2.4 Hours||2.05 Hours|
|180 AH||17.28 Hours||8.64 Hours||5.76 Hours||4.32 Hours||3.46 Hours||2.88 Hours||2.46 Hours|
|200 AH||19.2 Hours||9.6 Hours||6.4 Hours||4.8 Hours||3.84 Hours||3.2 Hours||2.74 Hours|
|220 AH||21.2 Hours||10.56 Hours||7.04 Hours||5.28 Hours||4.23 Hours||3.52 Hours||3.01 Hours|
|240 AH||23.4 Hours||11.52 Hours||7.68 Hours||5.76 Hours||4.6 Hours||3.84 Hours||3.3 Hours|
- Above Calculations are made assuming, Voltage – 12v; Battery Efficiency – 80%.
- For loads above 700 Watt per hour, it is recommended to buy for double or triple battery to fulfill the requirement.
OUR TOP PICKS FOR YOUR INVERTER BATTERY NEEDS:
LUMINOUS INVERLAST ILTT 18048N 150 AH TALL TUBULAR BATTERY MORE LIFE, MORE BACK UP
US INVERGEL IGSTJ 18000 150 AH GEL TUBULAR BATTERY Maintainence free, leak proof
The watt that each appliance uses is usually mentioned in the package of the appliance. Alternatively, you can search for the watt usage of any appliance on the internet and use those estimated figures to do your calculations.
One can find the battery capacity on the battery user manual or product description or on the face of the battery itself. 100 Ah, 120 Ah, 135 Ah, 150Ah, 180Ah, 200 Ah 220Ah,240 Ah, etc are the capacity of the battery.
Yes, a good company’s inverter would show an estimate on it. This time is calculated based on how much battery is charged and how many appliances are being powered at that given moment.
A min backup time of 3-4 hours is good. However, if your area has more frequent or long power cuts, go for 6 to 8 hours.
Among Gel, Tubular, Flat types of batteries, we recommend going for Tubular batteries as they are built for Emergency, quick and maximum backup. Within Tubular, go for Tall tubular as they come with many other benefits.
We recommend going for above 200 Ah batteries depending on your load requirements. You can calculate the required battery capacity using this calculator.
We suggest going for above 150 Ah batteries depending on your load requirements. You can calculate the required battery capacity using this calculator.
You just need to multiply the number of batteries connected to the inverter by the above calculation.
So formula to calculate multi-battery inverter is : Backup Time (in hours) = [Battery Capacity (in Ah) x Input Voltage (V) x Efficiency %(n) / Total Load (In Watts)] x N
Where “N” is the number of batteries.
You just need to replace 24v in place of 12v to the above calculation.
So formula to calculate multi-battery inverter is : Backup Time (in hours) = [Battery Capacity (in Ah) x 24 v x Efficiency %(n) / Total Load (In Watts)]
The inverter battery capacity has no direct relevance for battery backup calculation.
I hope that this information helped you understand how an inverter battery's backup time is calculated and how you can get a longer backup time. In general, you'll have an estimated backup time displayed on the inverter battery but it is always a good idea to do some calculations while you are planning to buy a new inverter battery.
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