DC TO AC Power

Submitted: Friday, Jan 18, 2013 at 22:14
ThreadID: 100066 Views:1679 Replies:3 FollowUps:1
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Hi, I am sure that the experts on DC power can help me with a suitable rule of thumb!
So here it goes :
How many amps of DC current are required to get 1 amp of AC current, taking into account the normal inefficiencies with pure sine inverters?
Many thanks, Phil
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Reply By: Member - Frank P (NSW) - Friday, Jan 18, 2013 at 22:37

Friday, Jan 18, 2013 at 22:37
Phil,

It's about watts. 1 amp of AC current at an assumed voltage of 240V is close enough to 240 watts.

If your inverter is 100% efficient, 240 watts with a 12 volt supply would need 240/12 = 20 amps.

Add more for the inevitable inefficiencies

Cheers
FrankP

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AnswerID: 502909

Reply By: Peter_n_Margaret - Friday, Jan 18, 2013 at 23:27

Friday, Jan 18, 2013 at 23:27
As per the first reply...
As a rule of thumb, establish the wattage of what you want to run on the inverter and divide by 10 to give Amps at 12V DC.

Cheers,
Peter
OKA196 Motorhome
AnswerID: 502920

Follow Up By: Ozhumvee - Saturday, Jan 19, 2013 at 00:02

Saturday, Jan 19, 2013 at 00:02
Inverters are not 100% efficient so for a good one work it out at 85-90% efficiency and you should be in the ball park.
If the inverter is to be "on" all the time also take into account the standby current when working out your total DC needs.
Peter
1996 Oka Motorhome

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Reply By: Allan B (Member, SunCoast) - Saturday, Jan 19, 2013 at 10:06

Saturday, Jan 19, 2013 at 10:06
Phil,
For an approximate conversion, multiply the 240v amps by 22 to get the amps of the 12v.
This allows for 90% inverter efficiency.
Cheers
Allan

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AnswerID: 502940

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