Inverter

I just purchased an "inverter". Specifically, a Motomaster Nautilus 450W Power Inverter.

The instructions include the following caution : Output non-sinusoidal. Do not use with following equipment:

-small battery operated products such as rechargeable flashlights, some rechargeable shavers, and night lights that are plugged directly into an ac receptacle to charge.

-certain battery charges for battery packs with power tools. These chargers will have warning labels stating that dangerous voltages are present at the chargers battery terminals.

Primarily I wish to know if this invertor can be used to charge my 14.4V batteries for my mastercraft drill. I have the 1 hour charger. The charger does not have the warning mentioned above printed on it, but I no longer have the instructions that came with it. The charger is quite heavy and therefore I assume it contains transformer, rectifier, etc..

I'd also like to know what it is about the power supply design of some equipment that makes it incompatible with a non-sinusoidal power source.

Thanks, Russell Wardman

Reply to
Russell
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These low cost inverters are not sinewave output as like your power from the electricity supplier in your home. Any device that uses a power transformer can be damaged. Power transformers unless designed to use other types of waveform drives require sinewave drive.

You can only use devices that employ a switching supply, and or do not have any power transformer driven off the mains AC. Some types of electric drills (not the chargeable type that have a power transformer), A computer, some types of monitors, some types of printers, motor with brushes only, and other similar devices with work. Most audio amplifiers, CD players, and older models of VCR's use a power transformer. These cannot be used with this inverter.

These are very good for incandescent lighting, and other simple things. What you really need is a sinewave type inverter. This is going to be a bit expensive.

Reply to
Jerry G.

"Russell" wrote on 14/12/2003 :-

You should not use it with anything which might have transformer on the input, working at the frequency of the mains. Transformers do not take kindly to being connected to the square wave type output of an inverter. This includes anything with a wall wart.

Reply to
Harry Bloomfield

Is it correct to say that the transformer does not "take kindly" to the square wave because it passes the 60 hz component but the higher frequency energy is turned into heat by the core and the heat is then the destructive force? This seems logical, but does not explain the manufacturers warning not to use the inverter with chargers that warn of dangerous voltages at the the chargers battery terminals. Russell

Reply to
Russell

On 14/12/2003 "Russell" opined:-

YES!

I cannot think of a suitable explanation for this, so I will pass on that one.

Reply to
Harry Bloomfield

in article snipped-for-privacy@tiscali.co.uk, Harry Bloomfield at snipped-for-privacy@tiscali.co.uk wrote on 12/14/03 4:07 AM:

What is the basis for this statement? The only problem I can picture for a true transformer without electronics is possible saturation of the transformer core. Without doing the calculation, something you can do, compare the volt seconds for a sinusoidal transformer during a half-ve to that of a square wave of a square-wave having the same rms voltage.

Bill

Reply to
Repeating Rifle

You are correct that some devices should not be used with square waves particularly if they have an input transformer.

But is not that the higher harmonics are transformed into heat.

What is really happening is that the core of a transformer is designed to handle the volt seconds under the a sine wave. But a square wave has more volt seconds under the wave. This can cause the core to saturate and that is what is causeing the heat. If the voltage is lowered so that the core does not saturate, then the peak voltage of the square wave my not supply enough volts to operate the device.

It really has nothing to do with the harmonics, other than they may add volt seconds the core is not prepared to handle.. . . I DO NOT FOLLOW MANY OF THESE NEWS GROUPS To answere me address mail to snipped-for-privacy@aol.com

Reply to
BUSHBADEE

You are correct Bill, but some devices have capacitive input filters and the RMS voltage of the wave may not have much to do with theDC output of the dc filter. Often the voltage in these cases is more a function of the peak voltage.than the RMS voltage. . . I DO NOT FOLLOW MANY OF THESE NEWS GROUPS To answere me address mail to snipped-for-privacy@aol.com

Reply to
BUSHBADEE

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