SternWake
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I despise inverters, Yet I have 2 of them, both a pure sine wave and a larger MSW.
I view them as a necessary Evil.
Many people assume the inverter is the solution to all their power needs, when transferring stick and brick necessities/luxuries/conveniences to life on Wheels and battery power.
But the inverter is not very efficient, and many times it is employed to power devices which actually run/charge on DC electricity. So 12vDC battery power is transformed to 115vAC electricity, then the wallwart transformer takes this 115vAC and transforms it to 5vDC, in the cases of USB charged/powered devices.
Much more efficient to transform 12vDC to 5vDC, or in the case of most laptop car adapters, 12vdc to 19.5vDC.
Here, Mainesail measured the current consumed to charge an Ipad. Long story short, using a DC USB power supply was 27% more efficient than using a 400 watt inverter to power the DC transformer provided with the Ipad.
http://www.pbase.com/mainecruising/ipad_charge_&page=1
Similar savings can be employed by using a '12v car adapter' for their laptops as opposed to an inverter powering the original power transformer, brick/wall wart. Even charging a Smart phone is significantly more efficient via a 12b to USB transformer, compared to powering an inverter to power the Phones provided 120Vac to 5vDC transformer.
I have measured my laptop consumption powered by inverter vs 'car adapter' and the 27% figure is very close to my observations as well. It really depends on the task the laptop is performing as to how much more efficient it is.
If you have lots of battery capacity and lots of charging sources available this 27% is certainly no big deal. But many here are asking a lot from a single house battery with questionable recharging ability, and this 27% can easily make a huge difference in battery longevity, especially if combined with other means to keep the inverter Off.
A problem with 'car adapters' is the Ciggy plugs provided with them. Ciggy receptacles are a very poor electrical connection. When asked to pass 5 or more amps they heat up greatly, and the spring steel, which is not a great conductor of electricity also loses some spring, and allows the nipple spring to back the connector out of the socket receptacle. Then this nipple spring heats up greatly, exerts less pressure on the (+) terminal and the downward spiral becomes unstoppable until something melts.
Here a 150 watt inverter tip melted due to the poor connection inherent in Ciggy plugs: Scroll down a bit:
http://www.pbase.com/mainecruising/hall_of_fail&page=3
Do check out his other 'fails' that are applicable to life on wheels too.
So those requiring USB power to recharge, are much better off acquiring a 12vdc to USB power source. I very much like the BlueSeas Unit as it can maintain 5.18 volts under a 2.1 amp load, where as some others from to 4.78v under that same load and many USB devices will not attempt to recharge if voltage falls below 4.75v.
https://www.bluesea.com/products/1016/Dual_USB_Charger_Socket
These do have a slight parasitic draw even when powering/charging nothing. So, perhaps ones which fit into a ciggy receptacle could be a better choice as they can be pulled out just enough until the nipple contact breaks the circuit:
http://www.amazon.com/s/ref=nb_sb_n...ds=usb+car+adapter&rh=i:aps,k:usb+car+adapter
I have a few of these, but they cannot charge my phone as fast as the Blueseas unit can. Even 3.1 amps at 5v is only 15.3 watts, and this will not present an issue for even the worst of 12v Ciggy plug receptacles.
It is not easy to escape the ciggy plug 12v connector. They are too Widespread and common, but they really are an extremely poor connector.
The stock vehicle wiring leading to them is usually way too long and way too thin, so lots of voltage drop can occur even before the ciggy plug receptacle.
When voltage drop occurs, and the device being powered requires the same total wattage, then more amperage has to flow. More amperage causes more voltage drop, which causes more amperage to flow to fill that gap, causing more heating, more voltage drop, and round and round it goes till some magic smoke gets up and goes.
Some devices, like lighting or fans will just slow down/ or dim when the voltage reaching them is lower. If an inverter is being powered, it actually has to work harder to transform 10.8v to 115Vac than it would if it was fed 12.2v through thicker copper circuitry.
I used to have a 12v mattress heating pad, and when I cut off the ciggy plug in favor of 30 amp Anderson powerpoles it received a full extra Volt. It heated up significantly faster, and required less input to maintain temp, and overall used less battery power, as no battery power was wasted heating up the Ciggy plug connector interface.
Back to the inverters, they consume current just turned on powering nothing. My 800watt MSW consumes 0.62a turned on powering nothing, My 400 watt PSW inverter consumes 0.24a turned on powering nothing.
This is not much, but over the course of an Hour, my 12v compressor fridge consumes on average about 0.75a per hour.
So my 800 watt MSW inverter, turned on, powering nothing, uses nearly as much battery power as my 12v compressor fridge does to keep my food at 35F in that same hour.
So often on this forum someone decides to save a few hundred $$ buying a 100$ AC dorm fridge and powering it with an inverter.
But then one has to buy/already own a large enough inverter to power it, likely 1200 watts just to handle the start up surge. The one also requires more battery capacity, and more recharge capacity to power it. There are also lots of reports that even the most efficient dorm fridges double their claimed electrical consumption. A dorm fridge also requires a method to secure it to the vehicle and a method to keep the door from swinging open during hard right or left turns. There are also reports of dorm fridges not doing well in a high vibration environment, like a travelling vehicle.
So once again, the inverter might be viewed as a magical solution to powering household devices in 12vDC rolling world, but in the end it really just becomes a more expensive, less efficient option, a failure waiting to happen when Murphy dictates the time is right to really stick it to you.
Often there is no option but to use an Inverter, as no 12v device exists for the application. In such cases proper cabling to the Battery are the best ways to reduce inefficiency. Use short fat cables to battery from inverter, and Use AC household extension cords to reach more distant 115Vac appliances. A huge Inverter powering a Tiny load is less efficient than a smaller inverter powering that smaller load.
Also a common occurrence is having limited battery capacity, but then hooking a huge inverter to it, as More is always better, has been beaten into the consumer mindset. a 3000 watt inverter on a single group31 battery, and trying to power a 3000 watt load, is like putting a half gallon of gas in a dragster which requires 7 gallons to reach the 1/4 mile timer.
It really is so much easier and cheaper to conserve electricity than it is to have enough capacity and recharging sources to not worry about efficiency. This is so often overlooked, and the inverter makes it so easy to overlook.
I view them as a necessary Evil.
Many people assume the inverter is the solution to all their power needs, when transferring stick and brick necessities/luxuries/conveniences to life on Wheels and battery power.
But the inverter is not very efficient, and many times it is employed to power devices which actually run/charge on DC electricity. So 12vDC battery power is transformed to 115vAC electricity, then the wallwart transformer takes this 115vAC and transforms it to 5vDC, in the cases of USB charged/powered devices.
Much more efficient to transform 12vDC to 5vDC, or in the case of most laptop car adapters, 12vdc to 19.5vDC.
Here, Mainesail measured the current consumed to charge an Ipad. Long story short, using a DC USB power supply was 27% more efficient than using a 400 watt inverter to power the DC transformer provided with the Ipad.
http://www.pbase.com/mainecruising/ipad_charge_&page=1
Similar savings can be employed by using a '12v car adapter' for their laptops as opposed to an inverter powering the original power transformer, brick/wall wart. Even charging a Smart phone is significantly more efficient via a 12b to USB transformer, compared to powering an inverter to power the Phones provided 120Vac to 5vDC transformer.
I have measured my laptop consumption powered by inverter vs 'car adapter' and the 27% figure is very close to my observations as well. It really depends on the task the laptop is performing as to how much more efficient it is.
If you have lots of battery capacity and lots of charging sources available this 27% is certainly no big deal. But many here are asking a lot from a single house battery with questionable recharging ability, and this 27% can easily make a huge difference in battery longevity, especially if combined with other means to keep the inverter Off.
A problem with 'car adapters' is the Ciggy plugs provided with them. Ciggy receptacles are a very poor electrical connection. When asked to pass 5 or more amps they heat up greatly, and the spring steel, which is not a great conductor of electricity also loses some spring, and allows the nipple spring to back the connector out of the socket receptacle. Then this nipple spring heats up greatly, exerts less pressure on the (+) terminal and the downward spiral becomes unstoppable until something melts.
Here a 150 watt inverter tip melted due to the poor connection inherent in Ciggy plugs: Scroll down a bit:
http://www.pbase.com/mainecruising/hall_of_fail&page=3
Do check out his other 'fails' that are applicable to life on wheels too.
So those requiring USB power to recharge, are much better off acquiring a 12vdc to USB power source. I very much like the BlueSeas Unit as it can maintain 5.18 volts under a 2.1 amp load, where as some others from to 4.78v under that same load and many USB devices will not attempt to recharge if voltage falls below 4.75v.
https://www.bluesea.com/products/1016/Dual_USB_Charger_Socket
These do have a slight parasitic draw even when powering/charging nothing. So, perhaps ones which fit into a ciggy receptacle could be a better choice as they can be pulled out just enough until the nipple contact breaks the circuit:
http://www.amazon.com/s/ref=nb_sb_n...ds=usb+car+adapter&rh=i:aps,k:usb+car+adapter
I have a few of these, but they cannot charge my phone as fast as the Blueseas unit can. Even 3.1 amps at 5v is only 15.3 watts, and this will not present an issue for even the worst of 12v Ciggy plug receptacles.
It is not easy to escape the ciggy plug 12v connector. They are too Widespread and common, but they really are an extremely poor connector.
The stock vehicle wiring leading to them is usually way too long and way too thin, so lots of voltage drop can occur even before the ciggy plug receptacle.
When voltage drop occurs, and the device being powered requires the same total wattage, then more amperage has to flow. More amperage causes more voltage drop, which causes more amperage to flow to fill that gap, causing more heating, more voltage drop, and round and round it goes till some magic smoke gets up and goes.
Some devices, like lighting or fans will just slow down/ or dim when the voltage reaching them is lower. If an inverter is being powered, it actually has to work harder to transform 10.8v to 115Vac than it would if it was fed 12.2v through thicker copper circuitry.
I used to have a 12v mattress heating pad, and when I cut off the ciggy plug in favor of 30 amp Anderson powerpoles it received a full extra Volt. It heated up significantly faster, and required less input to maintain temp, and overall used less battery power, as no battery power was wasted heating up the Ciggy plug connector interface.
Back to the inverters, they consume current just turned on powering nothing. My 800watt MSW consumes 0.62a turned on powering nothing, My 400 watt PSW inverter consumes 0.24a turned on powering nothing.
This is not much, but over the course of an Hour, my 12v compressor fridge consumes on average about 0.75a per hour.
So my 800 watt MSW inverter, turned on, powering nothing, uses nearly as much battery power as my 12v compressor fridge does to keep my food at 35F in that same hour.
So often on this forum someone decides to save a few hundred $$ buying a 100$ AC dorm fridge and powering it with an inverter.
But then one has to buy/already own a large enough inverter to power it, likely 1200 watts just to handle the start up surge. The one also requires more battery capacity, and more recharge capacity to power it. There are also lots of reports that even the most efficient dorm fridges double their claimed electrical consumption. A dorm fridge also requires a method to secure it to the vehicle and a method to keep the door from swinging open during hard right or left turns. There are also reports of dorm fridges not doing well in a high vibration environment, like a travelling vehicle.
So once again, the inverter might be viewed as a magical solution to powering household devices in 12vDC rolling world, but in the end it really just becomes a more expensive, less efficient option, a failure waiting to happen when Murphy dictates the time is right to really stick it to you.
Often there is no option but to use an Inverter, as no 12v device exists for the application. In such cases proper cabling to the Battery are the best ways to reduce inefficiency. Use short fat cables to battery from inverter, and Use AC household extension cords to reach more distant 115Vac appliances. A huge Inverter powering a Tiny load is less efficient than a smaller inverter powering that smaller load.
Also a common occurrence is having limited battery capacity, but then hooking a huge inverter to it, as More is always better, has been beaten into the consumer mindset. a 3000 watt inverter on a single group31 battery, and trying to power a 3000 watt load, is like putting a half gallon of gas in a dragster which requires 7 gallons to reach the 1/4 mile timer.
It really is so much easier and cheaper to conserve electricity than it is to have enough capacity and recharging sources to not worry about efficiency. This is so often overlooked, and the inverter makes it so easy to overlook.
