PC Peripherals 8 Hrs powercut - need inverter for PC :(

[mehrotra.akash]

Friends 4days before i bought 875VA microtek inverter and 150AH okaya Big red Tubular battery.

Today i tested 540W load.i got battery low symbol after 2.30hours.

But i expect 3hours.Why it happend or my calculation wrong??

share your ideas soon

Thank you

Your calculation is wrong

The Ah ratings for batteries are for extended discharge (10 or 20 hours)

Faster discharge means lower apparent capacity

Also, there are conversion losses (DC-AC conversion)

Which one is yours?

http://www.okayapower.com/red-big.asp

I'm guessing SL 618 or 624

The C3 rating is 95Ah, which means you get around 2 hours approx at 540W

Maybe your load was slightly less than 540W

 

[NEWLIFE]

Your calculation is wrong

The Ah ratings for batteries are for extended discharge (10 or 20 hours)

Faster discharge means lower apparent capacity

Also, there are conversion losses (DC-AC conversion)

Which one is yours?

http://www.okayapower.com/red-big.asp

I'm guessing SL 618 or 624

The C3 rating is 95Ah, which means you get around 2 hours approx at 540W

Maybe your load was slightly less than 540W

Thank you for reply

My battery is SL600T 24+6 months warranty

i got calculation from some sites like this

[font=Arial, Helvetica, sans-serif]

Let's look for an Inverter which can give back-up of up to 3 hours, so for our case -​

[/font]

[font=Arial, Helvetica, sans-serif]

550W X 3Hours = 12V X Battery Capacity​

[/font]

[font=Arial, Helvetica, sans-serif]

Battery Capacity = (550 X 3)/12 = 137 Ampere Hours​

[/font]

[font=Arial, Helvetica, sans-serif]

So we need a battery of 137AH capacity but if you check the market you'll find batteries of 130AH capacity. So that should be more or less sufficient for your need.​

[/font]

[font=Arial, Helvetica, sans-serif]

It telling 130AH battery can give 3hours backup time with 550W load but mines is 150AH.so only i expect 3+ hours with 550W load.​

[/font]

[font=Arial, Helvetica, sans-serif]

mu calculation is 540/12=45​

[/font]

[font=Arial, Helvetica, sans-serif]

45*3hours=135(150AH-135AH balance 15AH for DC to AC conversion loss)​

[/font]

[font=Arial, Helvetica, sans-serif]

Explain plzz​

[/font]

 

[mehrotra.akash]

http://electronics.stackexchange.com/a/12727

The relationship between continuous current and time-to-full-discharge is NOT linear. You have discovered that when discharged at 3A, your 1.8Ah battery is delivering much less capacity (only about a quarter!) than a linear interpolation of the amp-hour rating would suggest. This is not unusual.

Similarly, your battery is rated for 150Ah @ 10 or 20 hours discharge rate, discharging it in 3 hours means a significantly lower apparent capacity

 

[gREen]

planned to upgrade my inverter,

bargained one of friend and he gave this quote,

luminous inverter 2kva

2 x luminous 180Ah battery for rs.30,000 + installation. so it should cast around 32k.

is this the best deal i can get?

 

[RTN]

Hi Kishore,
I just got a Microtek 900va Inverter and a 150ah tubular battery. During power cuts though the CFL bulbs lit and there was no indication of low battery, the inverter couldn't support my PC's Numeric 600va UPS. I also needed to know whether I should set the maximum charging voltage at high or standard. Can you help? Thank you.

 

[foruamit2004]

Hi Kishore,
I just got a Microtek 900va Inverter and a 150ah tubular battery. During power cuts though the CFL bulbs lit and there was no indication of low battery, the inverter couldn't support my PC's Numeric 600va UPS. I also needed to know whether I should set the maximum charging voltage at high or standard. Can you help? Thank you.

Nowadays all the inverters are capable of running in UPS mode(for PC). Just check the information about your model. If thats the case then you don't need your UPS anymore. Just switch on the UPS mode at the back panel of your invertor. There are usually 2 options - W-UPS(Wide UPS) mode which when selected your computer will restart, then the other mode will be UPS, which will work for computer.

 

[RTN]

Thank you Amit. Your reply helped me to discover that UPS mode is 180v-260v. Could you also kindly let me know the backup duration for 900va & 150ah battery if my usage is 500watts per hour.

 

[Crazy_Eddy]

backup duration for 900va & 150ah battery if my usage is 500watts per hour.

12V/150Ah battery? That gives you 1800 VAh. If you're draining 500W per hour, your approx backup should be around 3 hours.

 

[foruamit2004]

Thank you Amit. Your reply helped me to discover that UPS mode is 180v-260v. Could you also kindly let me know the backup duration for 900va & 150ah battery if my usage is 500watts per hour.

Crazy has already replied yo your query, the only thing with the UPS mode is that, when there is low input mains voltage then in UPS mode your invertor will be running on battery even though you have power in mains. So in areas where you have frequent low voltage problem, then your invertor will be running in battery mode most of the time. And may not be charged fully at times. So you should monitor that. If no issue as such, then you are good to go.

W-UPS - means it will be working on mains with wide range of voltage. UPS mode- means for sensitive electronic, will be working on the input voltage range you have posted.
Btw - I didn't see such mode(UPS/W-UPS) in the image you have posted.

Also - 500 watts looks a bit too much for general uses excepts when you are running coolers etc. (your battery will wear out faster if daily it is drained fully). also invest in LED bulbs etc.

I have same config as yours(battery+ inverter) - My computer takes almost 130 watts + 2-3 LED bulbs - 21 watts + 1 fan - 35 watts + sometimes 40 inch LED TV -which should be in the range - 60-70 watts. If there is long powercut. Then I will either switch off TV or Computer or both if not using. My batteries lasted about 6-7 hours using the above config and still didn't get low battery indicator, havn't tested more, as didn't have that long powercut.