BATTERY CONNECTED SYSTEMS
There are so many inverters on the market, what are the more important features to look for?
Firstly look for a recognised brand, this should give you the confidence that support will be available if needed.
Look for clear definition of specifications, are the power ratings continuous eg 24hrs. How long are the surge ratings. Does the Inverter have a Stand By circuit.
What is the Difference between an Inverter and an Inverter/Charger?
An Inverter Charger has the ability to use it’s existing circuitry to function as a battery charger when fed by an external AC source.
Normally when you start a generator or plug into shore power, the Inverter will not be needed. Instead of under utilising the inverter, it works in the reverse and acts as a battery charger. An Inverter/Charger saves space and weight. An Inverter only model will be more valuable in the unlikely event of a failure.
Is there really a difference between modified Sine Wave and True Sine Wave, or is it just advertising?
Despite what some dealers may tell you, there is definitely a difference between Modified and True Sine Wave. For this discussion we will ignore other difference between models and brands such as power, efficiency, surge ,safety and reliability.
When any AC appliance is manufactured, it is intended to run from a smooth 230-/240 Sine Wave input, with a frequency of 50Hertz. 99.9% of appliances will never be run from an inverter, so the appliance manufacturers don’t consider them in their design. |
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The above graph shows the two types of output, the smooth purple line is a Sinewave, this is what you get on mains electricity. Typically this will be around 96% pure, or is often described as 4% Total Harmonic Distortion (THD). The black squarer type lines are Modified Sinewave, these will vary from 40-70% pure. Notice how the peak of the Sinewave line is greater than the modified line, this would normally mean less voltage output from the modified inverter, but is made up by having wider shoulders. The problem with this, is that some appliances need to see the peak type of voltage that the Sinewave produces, and don’t want the extra voltage at the shoulders. The lack of peak from a modified Sinewave will result in appliance such as Microwave Ovens taking much longer to cook than normal, often twice as long. The wider shoulders of the modified Sinewave result in extra heating of the appliance. Extra heating within an appliance will often reduce the life of the appliance and premature failure of the appliance.
Whilst not every appliance will initially exhibit problems when run from a Modified Sinewave, here are some of the problems we have had reported to us by customers.
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Microwave oven takes twice as long to cook. |
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My TV has lines across the screen |
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My stereo has a low pitched hum through the speakers |
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The remote control on my stereo does not function correctly |
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My electronic speed controlled electric drill is very "jerky" when trying to run at a low speed. |
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The battery charger in my cordless drill keeps failing |
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My fluorescent lights have an audible buzz. |
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Ceiling fans run slow and are noisy. |
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