Lithium batteries

The term "lithium battery" refers to a family of different chemistries, comprising many types of cathodes and electrolytes. The battery requires from 0.15 to 0.3 kg of lithium per kWh.

The most common type of lithium cell used in consumer applications uses metallic lithium as anode and manganese dioxide as cathode, with a salt of lithium dissolved in an organic solvent.

Another type of lithium cell having a large energy density is the lithium-thionyl chloride cell. Invented by Adam Heller, Lithium-thionyl chloride batteries are generally not sold to the consumer market, and find more use in commercial/industrial applications, or are installed into devices where the consumer does not replace them. The cell contains a liquid mixture of thionyl chloride (SOCl₂) and lithium tetrachloroaluminate (LiAlCl

 which act as the cathode and electrolyte, respectively. A porous carbon material serves as a cathode current collector which receives electrons from the external circuit. Lithium-thionyl chloride batteries are well suited to extremely low-current applications where long life is necessary, such as wireless alarm systems.

They stand apart from other batteries in their high charge density (long life) and high cost per unit. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5 V (comparable to a zinc–carbon or alkaline battery) to about 3.7 V.

By comparison, lithium-ion batteries are rechargeable batteries in which lithium ions move between the anode and the cathode, using anintercalated lithium compound as the electrode material instead of the metallic lithium used in lithium batteries.

Lithium batteries are widely used in products such as portable consumer electronic devices.

DC Contactors

A DC contactors is an electrically controlled switch used for switching an electrical power circuit, similar to a relay except with higher current ratings. It is controlled by a circuit which has a much lower power level than the switched circuit.

It come in many forms with varying capacities and features. Unlike a circuit breaker, it is not intended to interrupt a short circuit current. Range from those having a breaking current of several amperes to thousands of amperes and 24 V DC to many kilovolts. The physical size ranges from a device small enough to pick up with one hand, to large devices approximately a meter (yard) on a side.

Contactors are used to control electric motors, lighting, heating, capacitor banks, thermal evaporators, and other electrical loads.

Operating principle

Unlike general-purpose relays, contactors are designed to be directly connected to high-current load devices. Relays tend to be of lower capacity and are usually designed for both normally closed and normally open applications. Devices switching more than 15 amperes or in circuits rated more than a few kilowatts are usually called contactors. Apart from optional auxiliary low current contacts, it almost exclusively fitted with normally open ("form A") contacts. Unlike relays, it designed with features to control and suppress the arc produced when interrupting heavy motor currents.

When current passes through the electromagnet, a magnetic field is produced, which attracts the moving core of it. The electromagnet coil draws more current initially, until its inductance increases when the metal core enters the coil. The moving contact is propelled by the moving core; the force developed by the electromagnet holds the moving and fixed contacts together. When the coil is de-energized, gravity or a spring returns the electromagnet core to its initial position and opens the contacts.

energized with alternating current, a small part of the core is surrounded with a shading coil, which slightly delays the magnetic flux in the core. The effect is to average out the alternating pull of the magnetic field and so prevent the core from buzzing at twice line frequency.

Because arcing and consequent damage occurs just as the contacts are opening or closing, they are designed to open and close very rapidly; there is often an internal tipping point mechanism to ensure rapid action.

Inverters

A power inverter, or inverter, is an electronic device or circuitry that changes direct current (DC) to alternating current (AC).

The input voltage, output voltage and frequency, and overall power handling depend on the design of the specific device or circuitry. The inverter does not produce any power; the power is provided by the DC source.

A power inverter can be entirely electronic or may be a combination of mechanical effects (such as a rotary apparatus) and electronic circuitry. Static inverters do not use moving parts in the conversion process.

Input voltage

A typical power inverter device or circuit requires a relatively stable DC power source capable of supplying enough current for the intended power demands of the system. The input voltage depends on the design and purpose of the inverter. Examples include:

• 12 VDC, for smaller consumer and commercial inverters that typically run from a rechargeable 12 V lead acid battery.
• 24 and 48 VDC, which are common standards for home energy systems.
• 200 to 400 VDC, when power is from photovoltaic solar panels.
• 300 to 450 VDC, when power is from electric vehicle battery packs in vehicle-to-grid systems.
• Hundreds of thousands of volts, where the inverter is part of a high voltage direct current power transmission system.

Output waveform

An inverter can produce a square wave, modified sine wave, pulsed sine wave, pulse width modulated wave (PWM) or sine wave depending on circuit design. The two dominant commercialized waveform types of inverters as of 2007 are modified sine wave and sine wave.

There are two basic designs for producing household plug-in voltage from a lower-voltage DC source, the first of which uses a switching boost converter to produce a higher-voltage DC and then converts to AC. The second method converts DC to AC at battery level and uses a line-frequency transformer to create the output voltage.

Solar Charge Controllers

Charge controllers are sold to consumers as separate devices, often in conjunction with solar or wind power generators, for uses such as RV, boat, and off-the-grid home battery storage systems. In solar applications, charge controllers may also be called solar regulators. Some charge controllers / solar regulators have additional features, such as a low voltage disconnect (LVD), a separate circuit which powers down the load when the batteries become overly discharged (some battery chemistries are such that over-discharge can ruin the battery). 

A series charge controller or series regulator disables further current flow into batteries when they are full. A shunt charge controller or shunt regulator diverts excess electricity to an auxiliary or "shunt" load, such as an electric water heater, when batteries are full. 

Simple charge controllers stop charging a battery when they exceed a set high voltage level, and re-enable charging when battery voltage drops back below that level. Pulse width modulation (PWM) and maximum power point tracker (MPPT) technologies are more electronically sophisticated, adjusting charging rates depending on the battery's level, to allow charging closer to its maximum capacity. 

A charge controller with MPPT capability frees the system designer from closely matching available PV voltage to battery voltage. Considerable efficiency gains can be achieved, particularly when the PV array is located at some distance from the battery. By way of example, a 150 volt PV array connected to an MPPT charge controller can be used to charge a 24 or 48 volt battery. Higher array voltage means lower array current, so the savings in wiring costs can more than pay for the controller.

Charge controllers may also monitor battery temperature to prevent overheating. Some charge controller systems also display data.