Inverter Q & A:

How long will my batteries last? Each time I run my inverter a high pitched alarm is sounding?

This is the most often asked question regarding power inverters, and is the most difficult to answer. The length of time that your batteries will last is proportionate to the size of the battery, the load of your inverter, what other loads are running from the battery and what charging sources are connected. Without knowing all of these factors no one can give a precise answer.

What we can however do is look at the power requirements of the appliances you need to run, how long do you intend to run them and what other DC appliances are going to use the batteries. For a complete break down on this, look at page 24 & 25 for simple workings to determine your battery and charging requirements.

The high pitched alarm being experience can come from two problems: Insufficient battery cables creating voltage drop, or, a depleting battery capacity. If the alarm keeps going off, even when your batteries are fully charged, have someone look at your battery cable set up for undersized cables, or loose connections powering the inverter.

How much power will my inverter draw? I left my inverter on all night and now nothing works?

The power required to run an inverter is approximately 10% of the power load of the appliances being run. An easy formula to use to work out how much power you will use from your battery, simply divide the AC wattage of your appliance by 10 (10 is a simple figure that allows for the losses and inefficiencies of the power inverter at 12 volts divide by 20 for 24 volt systems).

Inverters will draw power from your batteries when not in use, and the unit is turned on. This can vary from around .02 amps right up to 2amps depending on the unit and design of their standby systems (low cost inverters generally draw more than quality units). If you leave your inverter turned on with no load attached, the draw from your batteries will be 1 amp per hour; 24amps per day; or 168 amps over a week. The simplest solution to this is to just turn the inverter off when not required as the battery drain then becomes zero. Many of our inverters feature standard or optional remote on/off controls.

What size batteries do I need?

The simple method of working this out, is to find the largest constant AC load you plan to run from your inverter (in most cases a microwave is the largest appliance), and divide this wattage x 5 (20% of your load). This will give you a rough idea of how much battery capacity you require to sustain your loads. With the example above, the microwave draws around 1000 watts AC, so a battery bank of around 200amphours would be required.

What size inverter do I need?

For help in this area, click here for a complete product power usage guide.

Sizing your inverter is a difficult task, and is not made any easier by different brands and manufacturers rating the power of their units at different temperature ratings. The power output of an inverter is dramatically decreased as its internal temperature rises (this is sometimes called its 5, 10 & 30 minute rating; but in reality if the inverter cannot remove the heat quick enough, then the power will rapidly drop off). Many of our models are rated at a staggering 40°C, such as Prosine, with a classic comparison between a Prosine 1000 and a low cost 1500watt modified as follows. The following table provides a comparison between the Prosine 1000i rated at 40°C and a common 1500watt inverter rated at 25°C.

My inverter is running very hot, is this alright?

Power generation creates heat, so yes your inverter will get warm. For this reason it is important to keep your inverter in a location that is cool and dry, and located in an orientation that will help assist with ventilation (e.g. you are not blocking the intake vents or fans with clothes or tools).

If your inverter gets too warm, it will simply shut down until the unit cools down. As mentioned above, the hotter your inverter gets, the less AC power it will deliver (hence the new designs such as Prosine that allow for rapid removal of warm air from the inside workings).

When measuring the AC voltage from my inverter, the multimeter is only showing 183 volts AC.

What's wrong with my inverter?

A common question and one that has nothing to do with the inverter. If your multimeter is registering this type of voltage, you have two things to consider; 1) the inverter is a modified sine wave type; & 2) you are using a non-true RMS multimeter (your meter is probably a fairly inexpensive unit). Because a multimeter assumes that it is measuring a pure sine wave output (non true RMS meters), it cannot measure the chopped output of the modified sine wave inverter. If you have this problem, rest assured that your system is working fine and you are receiving the required 230vac to your appliances. If certain items are not working, then this will be the modified sine wave, not the power.

When using my television off the inverter, there are a number of fuzzy lines across the screen.

Again a result of using a modified sine wave inverter. Many appliances react to this type of waveform (such as televisions generating lines across the screen, or radios having a hum through the speakers). There is not a great deal you can do to stop this except to upgrade to an Alessi or Prosine pure sine wave inverter. Try twisting the battery cables together and then wrap them in alfoil, as well as moving the inverter as far away from the interfered appliance as possible (these are merely suggestions and may not work in every case).