Enough of power cuts in the region I live and it became inevitable to buy an inverter/home UPS system. So I went ahead and did some very basic research before deciding upon buying the same. I am sharing the same over here in anticipation that it would help someone 
With loads of power backup options available in the market, it becomes quite a bit of an exercise to get to the right product. More so because of the aggressive marketing of the products, which may be misleading. Before even getting into the options, one needs to figure out the needs. For example, in my case I wanted a solution which would give a back-up of 2-3 hours for the following:
| S. No. | Equipment | No. of Units | Approx. Wattage / Unit | Total Wattage |
| 1. | Fan | 3 | 70 | 70*3 = 210 |
| 2. | CFL | 4 | 25 | 25*4 = 100 |
| 3.. | Notebook | 2 | 75 | 75*2 = 150 |
| 4. | TV | 1 | 120 | 120*1 = 120 |
| 5. | Miscellaneous (Modem, Router etc.) | NA | 50 | 50*1 = 50 |
| Total | 630 W | |||
So, I need a solution which can give me 630 W of power for 3 hours at a stretch (assuming I run all of the above for 3 hours). Now let’s do some high school physics calculations:
P (Power in Watts) = V (Voltage in Volts) * I (Current in Amperes)
Before we move ahead into the calculations, let’s clarify a couple of points:
What is the difference between an inverter and a UPS?
Well some think that these two are competing concepts, however the bottom line is that an ‘inverter’ is an equipment to convert Direct Current (D.C.) into Alternating Current (A.C.) where as an UPS (Uninterrupted Power Supply) is a circuitry which allows an instantaneous switch to the backup power source in case of a power failure thereby ensuring an uninterrupted power supply to sensitive equipments like a computer.
Now the only thing which needs an uninterrupted power supply in my list of equipments is the notebook, but that is anyway ensured by the notebook battery. So do I need a UPS? Well yes, I would want an uninterrupted internet connection in case of a power failure so I need the modem and router running in continuum.
Now that I know I need an inverter with UPS, do I need to look into anything else? Well yes, there are different types of inverters available in the market:
Square Wave Inverters: Popularly known as ‘Digital Inverters’ produce a Square Wave AC output which is not so great to run appliances as all the appliances are designed to run on a Sine Wave Alternating Current Pattern. Also, you would notice a humming sound in some of the appliances. Though electrical appliances would bear this, running electronic appliances over Square Wave is not at all recommended.
Sine Wave Inverters: These inverters produce the right wave pattern (Sine Wave) for which the appliances are designed. One can safely run most of the appliances on such current output.
Quasi Sine Wave Inverters: These fall somewhere in-between the above. I am not too sure about the internals. Also, didn’t find them in the market. But apparently they offer a low cost solution to run PCs and other electronic equipments on inverters.
Now what remains is the power storage medium, which, of course, is the battery. Again loads of options available which only confuse you. I didn’t think a lot over this and decided to go with an Exide Tubular Battery. Let’s have a real quick glance at the main options available relevant to inverters:
Standard Batteries: Loads of them available in the market. But they need maintenance i.e. putting in the distilled water on an ongoing basis.
Maintenance Free Batteries: While some claim they don’t need maintenance throughout their life-time, most of the maintenance free batteries need maintenance once a year or so.
Tubular Batteries: These batteries are superior in technology, construction and the quality of material used within. While you can figure out some nitty gritty here and here, they offer the following advantage:
- They are maintenance free.
- Long life (5+ years)
- Faster Charging
- More efficient
Though tubular batteries are a bit expensive, but considering their advantages I concluded that in the long-run, they actually turn out cheaper.
To wrap this up, let’s quickly get back to the calculations. So I needed a solution which could provide me with 630 Watts of power for 3 hours. Inverters available in the market are generally rated in VA/KVA.
Since, V*A=P, I need a 630 VA inverter. A very important point to keep in mind is the power factor. You would never get the rating mentioned in the inverter specifications. Considering a power factor of 0.8 (again figured out with some research) I would need an inverter with the following rating:
xVA * 0.8 = 630 VA
=> x= 630/0.8 = 787 VA
Luckily, for me we have 800 VA inverters available in the market, which perfectly fit to my needs. Note that this is a limiting factor w.r.t. the total wattage of appliances you can use. For instance I can’t run a 1000 watt appliance on an 800 VA inverter!
Now the battery. Inverter batteries are usually available in 12 V and are rated in Ampere Hours (AH). Since P=V*I and I need a backup for 3 hours,
630 W * 3 Hours = 12V * x (Ampere Hours)
=> x = (630 * 3)/12 = 157.5 AH
Again, luckily I discovered that we have batteries rated 165 AH in the market. So I decided to go with it.
Bingo! I have the details now. I need an 800VA inverter and a 165 AH battery for my needs. I just need to decide upon a brand based on the reviews.
Also, note that the above calculations are indicative. To quickly figure out how much back-up you would get while running a subset of the wattage considered at the time of buying, use the following:
Backup Time (Hours) = (Battery Voltage * Rating (in AH))/ Wattage required.
So if I just run 3 fans, i.e. 210 Watts, I would get a backup time of (on a fully charged battery):
12*165/210 = 9.4 hours
I can also run two moderate air coolers for about 7 hours. That’s sufficient for a night’s sleep
Comments
i have sukam 650va inverter and how can installed 150Ah two same size battery in this inverter .
i purchased SKN-H2000 (1200watt) invertor (China Made)
In the specification it requied 24 volt DC
12+12 two battery
In the specification there is no mentioned what is the Ampere of each battery.
My question is that Can I used 150AH or 200Ah bettery with this invertor and this AH ratio is not harmful for my inveter.
If the rating of your inverter is 24 volts than you can connect two 12v battery in series i.e connect +ve of 1st battery to -ve of second battery.Treat this combined batteries as single battery and connect it to inverter as per instruction.
Both batt should be of same make and age and identical in every respect as far as possible.Prefferably use new batt of same make every time.Dont worry about amperage.
Both bats should be connected in series i.e. +Ve of one bat goes to -Ve of the next bat and so on.
I want to run 2 fan 2 tubelights and for 6 hour , pl suggest product most suitable for me. thanks
Hi Everyone, thanks for reading and the comments. Unfortunately I have lost track of the calculations and latest options available for the inverters so I wouldn’t be able to help much. But I hope you can still use the indicators to make an informed decision about the purchase.
Thanks!
[...] the cost. Generator is another option but they make a lot of noise and are costlier. I found this excellent article which helped me decide what specifications I needed for the inverter. But unlike what is mentioned [...]
i am having internetcafe + online centre . iam giving my priducts details here. 2 computers + 6 nos ( 15.6 lcd monitors ) +1crt monotor (17′)+ 3 ceiling fans + 3 cfl bulbs . for these all run 2-3 hours back up . for this one wht is suitable for me . thanking you in advance . inerter or ups ? how much capacity . give details with battery
Cant ever thank you less for such a wonderful post. The number of comments speak about it all.
Great informative post !
I planned to go for 1000 VA and 2 Tublar Exide Batteries 167 ah .
How many hours backup can i get from batteries ?what’s the cost of the batteries?
What is the cost of 1000VA?
Can we connect 167ah batteries to 1000VA[for APC Inverter]?
Please answer to the above questions
Can I plan to go for 1000 VA and 2 Tublar Exide Batteries 156 ah .
How many hours backup can i get from batteries ?what’s the cost of the batteries?
What is the cost of 1000VA?
Can we connect 156ah batteries to 1000VA[for APC Inverter]?
Please answer to the above questions
Please note that as you increase the battery capacity, i.e., Ah, then there is a charging load on the inverter. Tubular batteries usually can withstand a higher charge current and also require a higher charging current. Most normal branded inverters may not be able to support high-end tubular batteries that require a higher charging current. In which case you want consult inverter manufacturers for a specialized inverter to fit the battery. Exide EL+ is among the high-capacity long-life battery requiring a higher charge current as the Ah rating goes up.
can i charge two 150AH of 12V batteries by a 800VA home ups pure sine wave inverter ? if can,how i will connect both batteries with the home ups pure sine wave inverter.
Connect both battery in parallel i.e join +ve terminal of 1st batt to +ve terminal of second batt and -ve terminal to -ve terminal.Treat this combined battery as a single battery.Connect it with inverter in usual manner. It will be a battery of 12v (150+150)=300 AH. Inverter will treat tis as a single 12v battery of 300AH.
Both batt should be of same make and age and identical in every respect as far as possible.Prefferably use new batt of same make every time.
Great friend. you cleared my doubts.
thanks & Regards,
pluskb
we are dealing with inverter,ups(on line & off line),solar street lights,home lights, inverters. If anybody wants to purchase please touch with my mail id. my phone no is 9790540724
we are dealing with solar & electronics.my contract no is 9790540724
A small correction in Amit calculation in finding battery rating as
630 W * 3 Hours = 12V * x (Ampere Hours)
=> x = (630 * 3)/12 = 157.5 AH
It should be
800W * 3 Hours = 12V * X(AH)
X = 200AH
Amit needs 200AH rated battery
The 800W is the Inverter rating, the battery has to deliver full 800W and Inverter inturn can deliver only 630W. ( 80% of 800W appx)
Please note that, its on full load calculation only.
Ppl,
The idea is stunning… We do not need inverter at all ( for basic support to fan and lights only )
http://www.mouthshut.com/review/Choosing_an_Inverter-196204-1.html
Please post your views on this
Hi
Your site is just wonderful.
I am looking for an Inverter with the following things to run
2 Table fan
2 CFL
1 PC
1 Laptop
1 Wimax Modem
Battery backup min 3hrs in full load.
Which Model of Inverter I should buy and Which Tubular Battery I should buy.
Thanks in advance.
Great article, Thank you
i need some help
i want to buy a inverter and will be running teh following
PC
- 22″ lcd
- with gfx card
- Modem
Tv
- 21″ CRT
CFL
- 3~4 ( total abt 50 – 60 watts )
Fans
- 1/2
i need at least 3 hrs backup,
and do i need to add a UPS before the pc ?
and which type of inverter to go for ?
thank you
Hi… I need inverter and tubular battery
I choose Sukam brand, sine wave 800VA inverter and Sukam 180Ah Tubelar Battery,
I have 2 CFL, 1 system TFT Monitor 20″ Desktop, 2 Fans, and 21″ Samsung Color TV.
It is sufficient for above product? and how many hours its coming after power cut?
hi, i have purchased 650va sukam inverter with exide mhd800 battery in Jul 2010 and it is working properly. But i have a doubt that this inverter may cause damage to the battery due to high charging current. Pl give any sugestion
Use only inverter battery ,tubular or flat.always keep a check on its electrolyte layer. As long as inverter is OK it will not damage the battery. Circuit provides checks and balances unless it is a cheap and non branded inverter.
Hi,
I have planned to buy
Microtek Inverter 800 V (sine wave) &
Exide SF Sonic 150 Ah.
Whether it build a healthy power back combination?
I have planned to buy in one or two days!!
BR,
Ajith
great work boss.
Excellent blog.. Certainly helping me in buying a UPS + battery combination. Thanks
Great blog! Wonder why it’s not rated higher in Google search results.
Will keep these points in mind when buying an inverter. Am planning to go for Su-kam 800VA inverter with 150AH Exide Inva Tubular battery (IT-500).
Hope to write my own review on this after purchasing the product.
Regards
Vijay
Very helpful blog. I too have decided to go in for a 800+ inverter with 150AH (IT 500) exide battery.
Thanks and Regards
Vaidyanathan
Hi..
very useful.. It helped me to find out the correct Inverter & Battery based my need.
Thanks
Many many thnx a great post, may God give you all the happiness in available in this world.
Prey to Almighty, that you live long
With Blessings,
Your
Dalal uncle
Dec21,2010
Hi Amit, I had bought Microtek 600EB inverter and Exide 1350PLUS battery (135 AH). The shop keeper sent me the 850EB inverter in place of 600EB as it was not in stock and then he never changed. So in short I have 850EB inverter and battery with 135AH. Now after around 2.5 years the battery is showing up low battery (in spite of distilled water being full). I showed to a nearby electrician and he said that the combination of 850EB inverter and 135AH itself is incorrect. The inverter is charging the battery at higher ampere than the capacity of battery and this have caused the battery to damage now, and in the worst case it can even burst the battery one day.
Based on your research, do you have any idea about what combination can be considered correct? OR do you have any links where I can find this out?
Great piece of research here, Amit! It is only for your work that I got saved in my quest for a good battery and inverter. Wish you all success in life.
what would be the cost of Microtek sine 850 va inverter
and battery 150 amph
hello Amit,
I have an luminous UPS rating 600VA and exide inva queen battery , but the setup is giving back up for only 1.5 hrs for the load of 2 cfls 23 watts , 1 tv 21 inchs and during charging time it shows charging only for 30 minutes and then charging indicator light goes off, so what may be the problem for this ?
Now i am thinking to purchase the new UPS{800VA} and battery for the load of 2 cfls 23 w and 1 TV 21 inch .Please guide me for the appropriate products.And tell me the back up time for the load described above.
I am thinking for Pepteller UPS(800VA). is it will be better or not ?
1. No battery gives full 100% power back for example a 100Ah battery gives back only 80Ah at its full discharge.
2. It is better to choose efficient inverters e.g.over 90%. Otherwise it eats up 20-40% battery by itself.
3. Check discharge ratio. The ordinary lead acid battery can not be discharged more than 50% but deep cycle batteries can be discharged up to 80%. Depth of Discharge (DOD) is the main factor to determine the life of the battery.
Excellent write up. Explains the basics were clearly.
What is price of Su-KAM Falcon 800 VA Inverter.
Whether is it compatible with Exide Mega (150AH) Inverter Battery & also price of Exide Mega Battery
Rgds
Sathish
Wonderful piece of information!!!!!
Hi Amit,
Thanks for the great information. I have exide make inva tublar battery (IT500). I want ot buy an inverte. Plz tell me which will be better – microtek/luminous & which will be better sine wave/square wave
@Amit: Thanks for sharing this info.. brilliant analysis and a very helpful article. I am writing this during the first power outage in my home in Chennai since I installed an inverter earlier this week, and thought of sending a “thank you” your way (and thanks to my friend @arunsark who gave me this URL).
I (actually, both me and my friend @haipradeep) opted for V-Guard DU 800 sine-wave inverter (INR 6000) and 150 AH Exide Tubular battery (got it for INR 13000, MRP 17000+). Strangely, 165 AH is not available anywhere (spoke to at least 5 dealers) though I would have gladly paid for that. For those who might ask why V-Guard, since we hail from Kerala, V-Guard is a natural (albeit, costlier) choice.
PEPTELLER Inverters
India’s only branded company with LCD Display in Square wave inverter models 600VA & 800VA. There are many benefits of LCD Display.
1. Displays Load % while in backup mode: You can adjust your load to keep the load % at 50%. You will get double backup time. This is not possible with LED Inverter.
2. Displays battery status: You can know the battery charge status just like you see in the mobile phone. So, you can adjust the usage of inverter according to battery charge status and get backup when it is really required.
3. Display faults and their corrective measures: In case of Overload, the warning message of “OVERLOAD” is displayed along with “SWITCH OFF EXTRA LOAD”. You can easily correct the problems.
There are many more benefits. Please see attached product brochures.
To know more:
Log onto: http://www.pepteller.com
Or write a mail to: marketinginv@pepteller.com
the way u analyzed it is great,it was very useful than q
i have a xee bac 600va invertor i want to replace it with one kva inverter a shopkeeper tell me to buy a new 600va invertor oldd one fmor day amnd new one fmor ngight is peptellepr a good bprand
I am planning to purchase UPS/Inverter for 12 computers 5 tube light, 2 fans of 3 hours bachup , how much KVA I require and how many batteries I require please answer this?
Nagaraj
Hi,
I have bought micro tech 850 Invertor and Exide Invaqueen battary. Earlier it was working bit good, giving approx 6 hour backup.
Load arround 300 Watt approx.
After few month, It was even not giving 2 hours 15 watt. load.
Finally we came to know that two cell of battery are getting leackage and not good.
Now they are suggesting to replace this battery.
Can you plz help us on buying new battery.
Brand Name -
Model -
approx Price -
Currently we are using Microtech Invertor, by considering this, how can we get best bettery backup with quick full charge.
Here maximum we are facing problem with power cut.
Plz suggest.
- Deepak
hai….
amit…
tanx for ur information on ups/invertor/battery/and ussage…it is very helpful for me to decide the reqired ups and batteay…
with kind regards…
siva…
Use this link for calculating what you need to buy
http://www.anusolar.com/acload.htm
Dear Amit
Thanks for easy calculation mentioning on site ,i got good ready stuff from u. Do well in future .
Regards
Vijay Patel
Katni
Good homework Amit.
I wish to purchase UPS. My requirements are 3 Fans and 5 Tube Libhts some times a PC also. What brand inverter and what brand with capicity Battery I hve to purchase. Please give valuable suggestions in this regard .
Thanking you
A.Ramaswamy
09486476641
aramaswamyma@gmail.com
i am planing to purchase UPS/ Inverter for 2fans 5 tube lights. please suggest inverter and battery capacity- If pooible brand also
A.Ramaswamy
Hi, Thanks a lot for your superb stuff. I was provided a sukam 800va inverter( Falcon home UPS) by a dealer. He suggests to replace the same with an ICON company inverter. Could you advice me if I accept his proposal? As I am not clear to choose the better one.
I’ll be grateful for a prompt reply.
with regards!
i need the price list of sine wave 800 va home ups batteries in hyderabad.