12 volt use vs. Inverter

[Bob F]

I was pondering a question the other day while plugging in my TV/VCR on board to watch a movie.Which uses more power? My TV switched to 12V and plugged into the cigarette 12V outlet, or the TV switched to 110v and using my Heart 2000 inverter?My initial assumption is that the TV uses the same. So does using the inverter increase my battery consumption?Bob

 

[Ed Schenck]

Depends. . .

on how the TV is designed. There is a converter(power supply)in the TV because most of the voltages are small DC. So it may be more efficient as a DC appliance than as a 110AC.But there should be a tag somewhere(or a manual) that gives you the amps for both modes. You will have to convert the AC amps to DC(times 10.2?)The other option is to measure it. My Link 2000 with my Heart 2000 would show the current draw to tenths of an amp. Any cheap ammeter, properly installed with a shunt, would tell you the amp draw.

 

[Don Alexander]

Inverter Efficiency

Bob,A powerful inverter is not happy running on very light loads such as your TV - I presume it is not a gigantic rear projection set!!!Inverter makers normally quote the efficiencies at very close to full load where they can reach 95%. However, on light load the power required just to keep the unit alive, plus the standing current required by the control circuitry will reduce the efficiency to between 10% and 20%.On the basis that your set was designed to operate from a 12 volt supply on a RV or the like, the designer will have optimised it at that voltage.The same goes for laptop computers.The 12v setting wins hands down (I have designed inverters for aircraft radios where the same argument applies)Regards,Don.

 

[Larry Long]

Some numbers

I believe your unit is essentially the same as my Heart Freedom 20. It's efficiency at full load is 84%. It's peak efficiency is 93%. If you have the remote control panel the system consumes 181 mA at idle. With the idle circuit disabled the no-load consumption is 496 mA.The biggest reason I want an inverter is CONVENIENCE. I find 12 volt appliances to be expensive, usually not what I really wanted, hard to find and generally inconvenient.

 

[Fred Ficarra]

OK Bob, I think you know the answer,

Based upon the previous answers, a TV running on your 12VDC system compared to the same TV running on your inverter that is running on your 12 volt system,,,,,,,or have I had too many glasses of wine tonight?

 

[Jim Rushing]

Its the Conversion

Every time you change voltage from AC to DC or the other way around you lose power. It is because the conversion is never 100% efficient. Your TV should show the power comsumed at the two different inputs. The DC power comsumption will be less than the AC power comsumption. This is because the solid state circuits in the TV use DC to operate. The only AC item left in most TV systems today is the picture tube and that will shortly be completely replaced by solid state components.

 

[Fred Ficarra]

Jims right

I left his part un-said because I just assumed most knew that electronic devices ran on DC.