| I have cooked a lot of batteries and ruined a lot of equipment over the past ten years using a modified sine wave inverter before I learned why.
It happens with sustained daily use over months. You will not notice much of a battery capacity drop charging your batteries once in a while.
It is very difficult to “filter” or “smooth” out an instantaneous drop in voltage followed by a short period of zero voltage followed by an instantaneous negative voltage. This is complicated by as the voltage of your battery bank drops the ”peak” voltage also drops. To compensate for this voltage drop the time the voltage is on lengthens and the time the voltage is off or at zero shortens. This is hard to deal with.
Inductive loads such as motors run slower, have less power and run noisier. The power is no longer simply the amps times the volts. For a short time there is a lot of voltage but no amps therefore no power. At the other end of the “½ cycle” there is no voltage but the amps are flowing, therefore no power. Power factor is a way of describing this problem, a simplified way of expressing power factor for a modified sine wave inverter is;
Power factor = time when both volts & current are present / time when current is present
Note; current in the denominator can be replaced by voltage in this simple explanation
A power factor of 0.75 means a 1 hp motor now produces only ¾ hp. That is why a skill saw or any power tool lacks power running off an inverter. Fridges and freezers are also affected.
Electronic equipment has difficulty dealing with this issue of full on, nothing and then full on of the opposite voltage. They prefer smooth sinusoidal changes.
Any equipment such as some sewing machines or motors using microprocessors to control the speed may become damaged. With sustained every day use they will eventually fail.
It can cause problems for electronic equipment such as printers, etc,
Over a period of time a modified sine wave inverter may ruin any battery and/or equipment that uses a transformer less capacitive voltage conversion system.
If you are planning on using an inverter on a full time basis for years to power labtops and other electronic equipment it would be prudent to install a pure sine wave inverter . |