inverter

Q: What is an inverter?

A: An inverter takes DC power (battery or solar, for example) and converts it into AC "household" power for running electronic equipment and appliances.

Q: Why are they called inverters?

A: Originally converters were large rotating electromechanical devices. Essentially they combined a synchronous ac motor with a commutator so that the commutator reversed its connections to the ac line exactly twice per cycle. The results is ac-in dc-out. If you invert the connections to a converter you put dc in and get ac out. Hence an inverter is an inverted converter. For more information about such converters see.

Q: How can an inverter be used?

A: With a large enough battery bank, almost anything within reason can be operated from a power inverter – this assumes that the inverter has the proper power output for the given load. Everyday appliances such as microwaves, power tools, TVs and VCDs, lights, audio/visual equipment, battery chargers, tube lights ,Fans and computers are common loads. An inverter sized for loads with heavy inrush current can be used to power air compressors, water pumps, heaters, ventilation fans, and air conditioners Kevin Pure Sine Wave inverters\Home UPS are ideal for running sensitive test equipment such as communications equipment, oscilloscopes, scales, high end stereos & video equipment, communications equipment, etc

Q: What is Sine wave ?

A: It is the ideal waveform for the transfer of AC power. There are two types of waveforms available. A "modified sine wave", and the "true sine wave".
Modified Sine Wave - The modified sine wave is not really a sine wave at all. It is more less a "stepped wave". It achieves voltage regulation by varying in width according to the battery voltage and the load. Thus, the wave is not as smooth as a sine wave. The quality of modified sine wave inverters should not be underestimated. They are highly capable, and (by narrowing the waveform) they save energy when running only small loads, as happens during most of the day in a typical home. Modified sine inverters have been successful in many thousands of remote home, RV and marine systems since 1986.
True Sine Wave - Also known as Pure Sine Wave, is the most reliable waveform and provides power almost identical to a standard wall outlet. The power produced fully assures that your "sensitive loads" will be correctly powered, with no interference. Some appliances are likely to require Pure Sine Wave including digital clocks, battery chargers, light dimmers, variable speed motors, and audio/visual equipment. For these reasons, true sine wave inverters can be more a more expensive choice.

Q: Why do I hear buzzing on my stereo when using a modified sine wave inverter?

A: Some inexpensive stereos use power supplies that cannot eliminate common-mode noise. These would require a sine wave inverter to operate noise-free.

Q: How do I know which inverter to buy?

A: Different devices require specific wattages to run correctly and efficiently. Please use this easy formula to determine the correct size inverter:
AMPS x 220 = Watts
Example: 10 Amp Cooling Unit X 120 = 1200 Watts

Q: What is the Low Voltage Alarm & Shutdown?

A: The low voltage alarm will sound when the DC source falls below 10 volts and the automatic shutdown will power off the inverter. This is done to save your battery(ies) so you can restart your vehicle.

Q: Is my inverter weatherproof?

A: No. Treat your inverter like you would your TV. You wouldn't put your TV outside in the rain, please don't leave your inverter there either. Be aware of lighting storms. If struck, your inverter would go into a permanent overload state and may even smoke it. If using in a marine environment, try to keep it tucked away underneath, in a dryer area.

Q: How do I charge the battery for my inverter?

A: Because inverters operate from a DC (Direct Current) power source, usually a battery bank (one or more batteries), the battery source will have to be recharged at some point. (Remember that a battery discharged more than 80% is probably close to being dead.) Depending on the inverter load and runtime required, most power use applications will be covered by the charged battery. If the load is large (air conditioner, large draw power tools, large microwave, food freezer, ice cream machine, etc.), the user should verify that the installed inverter is of large enough capacity to operate this power requirement.

• Battery installation tips.
• Connect high amperage accessories such as a winch to the top terminals only. Do NOT use the side terminals.
• Replace any cables and connectors that have corrosion, rust, or other damage.
• Do not install batteries in a non-ventilated or sealed compartment.
• Do not lift or handle the batteries by the terminals.
• Do not over tighten terminal bolts.

Q: What are some safety precautions to keep in mind?

A: Improper use of a power inverter could result in personal injury. Keep the inverter free from moisture as liquids conduct electricity, which may lead to serious damage or injury! Do not use the inverter near flammable materials or where fumes or gases may accumulate. The AC Output (neutral) wire should be ground, except in special applications.

Q: Is it possible to run an air conditioner on power inverters?

A: Yes, it is possible to operate a air conditioner in range using a higher-powered inverter and battery bank with the right capacity for power. Select an inverter and battery combination that takes into account the startup surge required by the air conditioner.

Q: What type of batteries should I use in my Inverter/Charger installation?

A: Kevin recommends using only high-quality deep cycle batteries in Wet, Gel or AGM etc.

Q: What is the difference between Automotive and Deep Cycle batteries ?

A: Automotive batteries are usually adequate for small inverters, (< 500 Watts). Deep Cycle (marine) batteries are best for larger inverters as they are designed for several hundred charge/discharge cycles. (Automotive batteries wear out much more quickly after heavy discharge)

Q: Are there any appliances that cannot be run on an inverter?

A: In general you can connect almost any appliance to an inverter, with a few practical exceptions. While the inverter can easily supply a heavy load like an electric heater, the battery capacity is often too low to maintain the supply for any great length of time. The same applies to air conditioning units. As long as the battery capacity is high enough you can use a large inverter to run a washing machine, a large single cooking element or a small two-ring electric cooker.

Q: Can I use my inverter in parallel with the generator or shore power?

A: Definitely not! If you have a generator on board or a shore connection you must install a Masterswitch. The switch is available with various applications, but its main function is to switch automatically and safely between shore, generator and inverter power.

Q: Can I run a computer on the inverter?

A: Yes, you can. All Kevin sine wave inverters can easily and safely supply a computer. In fact the output voltage from an inverter is often better than that from the electricity grid. A Kevin inverter, combined with a battery charger and a battery set, is often used as a back-up system on shore in places where the grid connection voltage is contaminated or unreliable.

Q: Can I run a microwave on an inverter?

A: Yes. You can connect any model of microwave to your inverter, but keep in mind that a 800 watt microwave consumes 1200 to 1300 watt from the 230V system, so you must make sure you choose the correct size inverter.

Q: How much battery capacity do I need with an inverter?

A: As a rule of thumb you can assume the minimum battery capacity for a 12V installation is about 20% of the inverter capacity. For a 24V installation this would be 10%. In other words the minimum battery capacity for an AJ1000-12 is 160Ah.

Q: Are there any appliances that cannot be run on an inverter?

A: In general you can connect almost any appliance to an inverter, with a few practical exceptions. While the inverter can easily supply a heavy load like an electric heater, the battery capacity is often too low to maintain the supply for any great length of time. The same applies to air conditioning units. As long as the battery capacity is high enough you can use a large inverter to run a washing machine, a large single cooking element or a small two-ring electric cooker.

Q: How much power does an inverter consume?

A: If you connect a 850W coffee machine to a Studer sine wave inverter, consumption will be 850W divided by the voltage of the electrical system (12V) = 70 Amperes. Add another 8% (100%-92% =8%) to this total for the inverter consumption. The total power consumption is then 70 Amperes + 6 Amperes = 76 Amperes. Of course a coffee machine is only in use for about 10 minutes so the actual Ampere consumption is relatively low (76 x 10 min = 13Ah).

Batteries

Q: What does deep cycle mean?

A: Deep cycle means using the battery in an application that will typically discharge 60% to 70% or more of the battery capacity. An automotive battery is an SLI (starting, lighting, ignition) battery. It's plates are designed to deliver maximum power for a short duration. Starting a car typically discharges an SLI battery only 1% to 3%. When an SLI battery is used in a deep cycle application, or in a vehicle with heavy accessory loads, the battery life will be shortened proportionally to how deeply it is cycled on a regular basis.

Q: When should I consider a deep cycle?

A: Any time you need the battery to supply all the operating power for a vehicle or other device. Additionally, deep cycle batteries should be used in vehicles that have heavy accessory loads where the alternator cannot maintain the battery in a fully charged condition. This is typical of large bow thrusters.

Q: How do small batteries, such as the Optima & SBS produce high power?

A: This new range of engine start batteries have been specifically designed to provide extreme high current very quickly whilst maintaining a high stable voltage. This is only possible if internal resistance is very low. This is achieved by using pure lead for plate construction. Ordinary batteries use lead-calcium alloy plates with a higher resistance that limits power output in high rate applications. Usually very large and heavy batteries - generally in excess of 100Ah are specified to compensate for this limitation.

Q: What are "dry" and what are "liquid" batteries?

A: The terms "dry battery" and "liquid battery" are restricted to primary systems and date from the early development of galvanic elements. At that time, a liquid cell consisted of an electrolyte-filled glass container into which electrochemically active electrodes were immersed. It was only later that unspillable cells which could be used in any position and had a completely different construction were introduced, these being similar to today's primary batteries. These earlier cells were based on paste electrolytes. At that time they were known as dry batteries. In this sense today's primary batteries are also dry batteries. The term "liquid battery" is in principle still applicable to certain modern secondary batteries. For large stationary lead-acid or solar batteries, liquid sulfuric acid is preferred for the electrolyte. For mobile applications unspillable, maintenance-free lead-acid batteries are recommended and have been available for many years. Their sulfuric acid is immobilized by a gel (or a special microglass mat).

Q: Leak-proof semi-traction batteries, are they available?

A: Yes. Dry from Sonnenschein and Squadron batteries are leak-proof. They use a gelled electrolyte and are leak-proof even when stored upside down. The Drymobil battery from Sonnenschein and Squadron are used on boats, in house trailers or in small electric vehicles (golf buggies, wheelchairs etc.).

Q: Does my deep cycle battery develop a memory?

A: Lead acid batteries do not develop any type of memory

Q: What type of charger should I buy?

A: An automatic charger offers the greatest convenience. Just plug the battery into the charger and the charger does the rest. Manual chargers, although equally effective at charging batteries, require a greater level of attention. Generally speaking, automatic chargers are priced higher than manual chargers

Q: Do you ever add acid to a battery?

A: Under normal operating conditions, you never need to add acid. Only distilled, deionized or approved water should be added to achieve the recommended levels mentioned above. When a battery is shipped in a dry state or accidental spillage occurs, electrolyte should be added to the battery. Once filled, a battery should only need periodic water addition .

Q: What are common mistakes made by lead acid battery owners?

A: Undercharging : Generally caused by not allowing the charger to restore the battery to full state of charge after use. Continually operating the battery in a partial state of charge, or storing the battery in a discharged state results in the formation of lead sulfate compounds on the plates. This condition is known as sulfation. Both of these conditions reduce the battery's performance and may cause premature battery failure. Undercharging will also cause stratification. Overcharging : Continuous charging causes accelerated corrosion of the positive plates, excessive water consumption, and in some cases, damaging temperatures within a lead acid battery. Deep cycle batteries should be charged after each discharge of more than 50% of the batteries rated capacity, and/or after prolonged storage of 30 days or more.

Chargers

Q: Can my Charger be used with lead acid and gel batteries?

A: Possibly. Some chargers can be adjusted manually to recharge either conventional Lead acid or sealed Gel batteries. This is usually done by means of an output adjustment screw or toggle switches. If your charger is not suitable the batteries will fail prematurely. If you are in any doubt you should contact the charger manufacturers.

Q: Can a standard automotive charger be used with my batteries?

A: If you are recharging a car or van the answer is yes. If you want to recharge large commercial batteries you must ensure the charger output is sufficiently high enough before charging commences. If you are charging deep cycle or traction batteries the answer is no. Deep cycle and traction wet lead acid batteries require a higher charging voltage and charge current than the average automotive charger can produce.

Q: How long will it take my batteries to fully recharge?

A: The amount of time it takes a battery to charge depends on the type of battery and charger and on how long it took to discharge (slow or fast). As a rule of thumb you can divide the battery capacity by the maximum charge capacity and add four hours. The four hours is for the so-called after-charging time, where the battery determines how much more current it needs to get back to a fully charged state. For example, an empty 200 Ah battery connected to a 40A battery charger would take about 200 divided by 40 = 5 + 4 hours to charge, 9 hours in total. If the battery had been only 50% discharged the calculation would be: 100 divided by 40 = 2 + 4 hours, 6 hours in total.

Q: When do I need to perform an equalization charge?

A: Equalizing should only be performed on vented wet lead acid bateries. How often this might occur with your battery will vary depending on your application. You will need to monitor your battery voltage and specific gravity to determine when equalization is needed. For example, it is time to equalize if the measured specific gravity values are below manufacturer's recommended values after charging (recommended value for Trojan Deep Cycle batteries is 1.277 +/- .007 at 80o F). Equalizing is also required if the specific gravity value of any individual cell varies 30 points or more. Reduced performance can also be an indicator that equalizing is necessary. Equalization should also be performed when individual battery voltages in a battery pack range greater than 0.15 volts for 6 volt batteries or 0.30 volts for 12 volt batteries. A good rule of thumb is to perform equalize charging once every 10 cycles.

Q: What type of charger should I buy?

A: An automatic charger offers the greatest convenience. Just plug the battery into the charger and the charger does the rest. Manual chargers, although equally effective at charging batteries, require a greater level of attention.

Q: What size charger should I buy?

A: A properly sized charger takes into account battery capacity and the time interval between charges. In applications where cycling is infrequent, such as weekend users, or infrequent or seasonal usage, a charger with an output current rating between 10 and 13% of the battery's rated 20-hour capacity will suffice. In applications where battery recharge must be accomplished within 8 to 10 hours, a three stage, automatic charger, rated at 20% of the battery capacity, may be required.