Formula of Inverter & Battery.

Electrical Load detail:

1. 2 No of 60W,230V, 0.8 P.F Fan.
2. 1 No of 200W,230V, 0.8 P.F Computer.
3. 2 No of 30W,230V, 0.8 P.F Tube Light.

Inverter / Battery Detail:

1. Additional Further Load Expansion (Af)=20%
2. Efficiency of Inverter (Ie) = 80%
3. Required Battery Backup (Bb) = 2 Hours.
4. Battery Bank Voltage = 24V DC
5. Loose Connection/Wire Loss Factor (LF) = 20%
6. Battery Efficiency (n) = 90%
7. Battery Aging Factor (Ag) =20%
8. Depth of Discharge (DOD) =50%
9. Battery Operating Temp =46ºC

Temp. °C	Factor
80	1.00
70	1.04
60	1.11
50	1.19
40	1.30
30	1.40
20	1.59

Calculation:

Step 1: Calculate Total Load:

1. Fan Load= No x Watt =2×60=120 Watt
2. Fan Load=(No x Watt)/P.F=(2×60)/0.8= 150VA
3. Computer Load= No x Watt =1×200=200 Watt
4. Computer Load=(No x Watt)/P.F =(1×200)/0.8= 250VA
5. Tube Light Load= No x Watt =2×30=60 Watt
6. Tube Light Load=(No x Watt)/P.F =(2×30)/0.8= 75VA
7. Total Electrical Load=120+200+60 =380 Watt
8. Total Electrical Load=150+250+75= 475VA

Step 2: Size of Inverter:

1. Size of Inverter=Total Load+(1+Af) / Ie VA
2. Size of Inverter= 475+(1+20%) / 80%
3. Size of Inverter= 712 VA

Step 3: Size of Battery:

1. Total Load of Battery Bank= (Total Load x Backup Capacity) / Battery Bank Volt
2. Total Load of Battery Bank=(380 x 2) / 24 Amp Hr
3. Total Load of Battery Bank= 32.66 Amp Hr
4. Temperature Correction Factor for 46ºC (Tp)=1
5. Size of Battery Bank=[ (Load) x (1+LF) x (1+Ag) x Tp] / [n x DOD] Amp/Hr
6. Size of Battery Bank= (32.66 x (1+20%) x (1+20%) x 1) / (90% x 50%)
7. Size of Battery Bank= 101.3 Amp/Hr

Step 4: Connection of Battery:
If We Select 120 Amp Hr , 12V DC Battery for Battery Bank:
Series Connection:

• Series configurations will add the voltage of the two batteries but keep the amperage rating (Amp Hours) same.
• Condition-I :
• Selection of Battery for Voltage = Volt of Each Battery <= Volt of Battery Bank
• Selection of Battery for Voltage =12< 24
• Condition-I is O.K
• No of Battery for Voltage = Volt of Battery Bank / Volt of Each Battery
• No of Battery for Voltage =24/12 = 2 No’s
• Condition-II :
• Selection of Battery for Amp Hr = Amp Hr of Battery Bank <= Amp Hr of Each Battery
• Selection of Battery for Amp Hr =3<=120
• Condition-II is O.K
• We can use Series Connection for Battery & No of Battery required 2 No’s

Parallel Configuration

• In Parallel connection, the current rating will increase but the voltage will be the same.
• More the number of batteries more will be the amp/hour.  Two batteries will produce twice the amp/hour of a single battery.
• Condition-I :
• Selection of Battery for Amp Hr = Amp Hr of Battery Bank / Amp Hr of Each Battery <=1
• Selection of Battery for Amp Hr =101/120 = 0.84=1 No’s
• Condition-I is O.K
• Condition-II :
• Selection of Battery for Voltage = Volt of Battery Bank = Volt of Each Battery
• Condition-II :Selection of Battery for Voltage for Amp Hr = 24<=12
• Condition-II is Not Full Fill
• We cannot use Parallel Connection for Battery as per our requirement But If We do Practically It is Possible and it will give more Hours of back

Series-Parallel Connection:

• Connecting the batteries up in series will increase both the voltage and the run time.
• Condition-I :
• Selection of Battery for Amp Hr = Amp Hr of Each Battery <= Amp Hr of Battery Bank
• Selection of Battery for Amp Hr =120<=101
• Condition-I is Not Full Fill
• Condition-II :
• Selection of Battery for Voltage = Volt of Each Battery <= Volt of Battery Bank
• Selection of Battery for Voltage = 12<=24
• Condition-II is OK
• We cannot use Parallel Connection for Battery

If We Select 60 Amp Hr , 12V DC Battery for Battery Bank:
Series Connection:

• Selection of Battery for Voltage = Volt of Each Battery <= Volt of Battery Bank
• Selection of Battery for Voltage =12< 24
• Condition-I is O.K
• No of Battery for Voltage = Volt of Battery Bank / Volt of Each Battery
• No of Battery for Voltage =24/12 = 2 No’s
• Condition-II :
• Selection of Battery for Amp Hr = Amp Hr of Battery Bank <= Amp Hr of Each Battery
• Selection of Battery for Amp Hr =3<=60
• Condition-II is Not Full Fill
• We can use Series Connection for Battery

Parallel Configuration

• Condition-I :
• Selection of Battery for Amp Hr = Amp Hr of Battery Bank / Amp Hr of Each Battery <=1
• Selection of Battery for Amp Hr =101/60 = 1.63=1 No’s
• Condition-I is O.K
• Condition-II :
• Selection of Battery for Voltage = Volt of Battery Bank = Volt of Each Battery
• Condition-II :Selection of Battery for Voltage for Amp Hr = 24=12
• Condition-II is Not Full Fill
• We cannot use Parallel Connection for Battery as per our requirement.

Series-Parallel Connection:

• Condition-I :
• Selection of Battery for Amp Hr = Amp Hr of Each Battery <= Amp Hr of Battery Bank
• Selection of Battery for Amp Hr =120<=60
• Condition-I is OK
• No of Battery for Amp Hr = Amp Hr of Battery Bank / Amp Hr of Each Battery
• No of Battery for Amp Hr = 120/60 =1.68 =2 No’s
• Condition-II :
• Selection of Battery for Voltage = Volt of Each Battery <= Volt of Battery Bank
• Selection of Battery for Voltage = 12<=24
• Condition-II is OK
• No of Battery for Voltage = Volt of Battery Bank / Volt of Each Battery
• No of Battery for Voltage = 24 / 12 =2 No’s
• No of Battery Required = No of Battery Amp Hr x No of Battery for Voltage
• No of Battery Required = 2 x 2= 4 No’s
• We can use Series-Parallel Connection for Battery

Summary:

• Total Electrical Load=380 Watt
• Total Electrical Load=475VA
• Size of Inverter= 712 VA
• Size of Battery Bank= 101.3 Amp/Hr
• For 120 Amp/Hr , 12V DC Battery : Series Connection & 2 No’s of Battery or
• For 60 Amp/Hr , 12V DC Battery : Series-Parallel Connection & 4 No’s of Battery