Inverters
Submitted: Sunday, May 27, 2007 at 12:16
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Member - Ian F (WA)
Hi, I have had a 150 watt inverter for 4 years and was wondering if there is a simple calculation to work out the DC current being drawn ?
Reply By: joc45 - Sunday, May 27, 2007 at 13:13
Sunday, May 27, 2007 at 13:13
Hi Ian,
The current drawn on the DC side will depend on the current drawn on the AC side. The factor in common is watts for both the primary and the secondary side of the inverter. Most modern
inverters are better than 80% efficient, so if you know the watts on the secondary side being consumed, then divide that number by 0.8 and you will get a good approximation of the watts on the primary side.
Then to convert to current, amps = watts divided by volts.
Gerry
AnswerID:
242683
Follow Up By: Member - stefan P (NSW) - Sunday, May 27, 2007 at 13:30
Sunday, May 27, 2007 at 13:30
According to my book with my inverter, it is running at 90%...
mine is 1500w
Stefan
FollowupID:
503673
Follow Up By: joc45 - Sunday, May 27, 2007 at 17:13
Sunday, May 27, 2007 at 17:13
Hi, Stefan
Yes, a lot of
inverters do run at 90% efficiency, but generally at full output - I quoted the 80% as a general minimum.
Because some of the internal circuitry requires a fixed amount of power, though small, to run itself, this does not reduce at lower power outputs, being reflected in a bit lower efficiency at low outputs.
The bigger
inverters don't require much more power to run the internal circuitry than low power
inverters, and therefore usually result in a bit better efficiency than small
inverters at full output.
Gerry
FollowupID:
503706
Follow Up By: Member - stefan P (NSW) - Sunday, May 27, 2007 at 19:20
Sunday, May 27, 2007 at 19:20
cool, learn something new everyday, I know squat about these things, just quoting from the book
Cheers Stefan
FollowupID:
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Reply By: Member - Ian F (WA) - Sunday, May 27, 2007 at 13:25
Sunday, May 27, 2007 at 13:25
Hi Gerry, Thanks for the info. I did have a rough idea but did not know about the losses etc. The inverter was bought from one of the
well known electronic stores. Ian
AnswerID:
242684
Follow Up By: Member - Ian F (WA) - Sunday, May 27, 2007 at 13:40
Sunday, May 27, 2007 at 13:40
Sorry Gerry, I just realised that I sent the reply to myself, stupid newbie's!!!!!
Ian
FollowupID:
503677
Reply By: Footloose - Sunday, May 27, 2007 at 19:44
Sunday, May 27, 2007 at 19:44
Why not just measure it ?
AnswerID:
242750
Follow Up By: Member - Ian F (WA) - Sunday, May 27, 2007 at 19:56
Sunday, May 27, 2007 at 19:56
I just could see the point in uprading to a larger unit if it would pull the guts out of the battery supply.
FollowupID:
503759