Ni-Cd batteries can also handle large transient currents, and can leave their nominal capacity even with relatively large power outlet. Available in many varieties, sizes and capacities including for high ambient temperatures, rapid charging etc. Can be assembled into “desired” shape and performance, is well proven. Energy density of 80-120 Wh / liter or 40-60 Wh / kg, nominal cell voltage 1.2V. Manufactured in cylindrical, prismatic (rectangular) and in the button form.

They are easy to maintenance charge, but require monitoring for quick charge.

Ni-Cd are at their best when working hard, and should always be fully discharged before recharging, otherwise the so-called memory effect occurs, in which the battery’s capacity will gradually degrade. Can usually be “repaired” with repeated full charge / discharge, or with equipment for reconditioning of rechargeable batteries. Due to the content of the heavy metal, cadmium is Ni-Cd covered by high environmental fees and is being phased out increasingly in both the EU and the rest of the world.

Ni-MH batteries are reminiscent of Ni-Cd for the most part and are more environmentally friendly as they do not contain any heavy metals. Have about 50% higher capacity than a corresponding physically similar Ni-Cd, energy density 280-340Wh / liter or 80-120 Wh / kg, nominal cell voltage 1.2V. Can not handle quite as high currents as Ni-Cd, self-discharge is also somewhat higher than with other systems which one should consider if the application means that there is a time lag between charging and use.

There is also a newer generation of Ni-MH cells that have very low self-discharge (Low Self Discharge or LSD cells). Primarily developed for home use and in smaller sizes (AAA and AA) up to about 2200mAh. The characteristics of charging Ni-MH generally follow the Ni-Cd with somewhat stricter control of voltage curve and temperature. The memory effect is less than for Ni-Cd. Manufactured in the same shape and structure as Ni-Cd, and often have, but not always, green coloured housing. The price is somewhat higher, but due to environmental fees for Ni-Cd, the overall cost is balanced down for Ni-MH.

Lithium-ion batteries have a very high capacity relative to volume / weight, 320-380Wh / liter eller150-200 Wh / kg and can be the right option when weight plays a major role. Are more expensive than the others, but prices are falling gradually as more and more start using this system. At present the automotive industry is the strongest proponent of research on batteries based on lithium chemistry.

The cell voltage lies at 3.7V often uses a single cell in for example mobile phones. Li-Ion always have a small add-on electronic circuit (PCM Protection Circuit Module) which provides for the safety, prevents overcharge / under-discharge etc. The charging technique is reminiscent of the lead battery’s, but the battery can be recharged in less time, down to 2-3 hours. During charging is monitored often the balance (voltage level) between the individual cells with a special electronic circuit (VBB) that can be a separate circuit board but which often is combined with the protection circuit. The balancing can be passive or active where the latter provides a faster and more accurate result.

The cells are built both cylindrical and prismatic (rectangular). Li-Ion batteries are becoming increasingly common in applications with low to medium power consumption.

Lithium-ion Manganese dioxide is a variant that is designed for high discharge currents. Lithium-ion has no memory effect, and requires no reconditioning, self-discharge rate is low. Must however be taken into account that electronic protection , etc., has a certain consumption.

Lithium-Polymer Lithium-ion Polymer Lithium-Polymer (Li-Pol) batteries have a similar chemical composition as the regular Li-ion cells. The construction is such that one, in principle can shape the cell in the desired way, a dream for the designer. There is no need basically for a “hard” housing, only plastic or aluminium foil and can be “squeezed” in an optimal way in for example the computer or the phone’s battery casing. Works like Li-Ion, best with low or medium flows, requires somewhat longer recharge time. Can pricewise be advantageous due to the simpler manufacturing than Li-Ion, and is the most common Li-cell in portable devices today.

Also called Lithium Iron Phosphate or LiFe cells. Belongs to the same family but has a different chemical structure and slightly lower cell voltage, nominally 3,2V, but usually with high current capacity and good of cycling -ability, up to 2000 cycles for certain types, they can even load faster than other lithium-ion cells. Energy density about 180Wh / liter or 90Wh / kg. They are more stable and less prone to thermal runaway compared with ordinary lithium-ion / Lithium-Polymer and in some cases require somewhat simpler monitoring circuits, like built-in balancing of the cell voltage between cells connected in series.

Several Li-ion based battery chemistries LiCoO2 Lithium-Koboltdioxid, LiMn2O4, Lithium-Manganese dioxide, LiNiO2 Lithium-Nickel oxide are some of the many battery chemistries with energy density between 200-300 Wh / liter or 100-130Wh / kg, several new chemical formulations can be expected in the future, mostly driven by the automotive industry in cooperation with battery manufacturers.

There is a less common variant of alkaline cells (primary cells) that are designed to be recharged. They have the usual non-rechargeable terminal voltage of 1.5V, can be recharged 10-50 times or more depending on how deep they are discharged. They can not handle especially high currents and require a special charger. One advantage is that they have the same terminal voltage as ordinary alkaline disposable cells.

There is a variety of lithium technologies, all characterized by very high energy density in relationship to weight  and volume and long shelf life, up to 10-15 years. Cell voltage 3.0-3.6V and manufactured in sizes and shapes as the usual consumer cells, as well as for PCB mounting and industrial use, for memory backup etc. Common types are lithium thionyl chloride (3.6 V) for small and medium-sized currents and Lithium-Sulfur dioxide and lithium-manganese dioxide (3.0V) for large currents, The latter are common in for example some cameras and flashlights. Today, there are even several manufacturers of lithium cells with 1.5V voltage (lithium iron disulphide, LiFeS2) that directly replace conventional alkaline consumer cells in AAA and AA-size and in 9V batteries. These have many good properties like good cold resistance, very long shelf life, good high current properties and so on. The price is higher than that of the alkaline cells but may be outweighed by the long running time, a classic example is the 9V battery for smoke alarms that can work up to 8-10 years before replacement must be done.

So-called smart batteries are something that can be seen with increasing frequency, also called Info batteries (in connection with cameras , for example) or intelligent batteries. Is not really tied to any particular chemical system has long been used in for example certain laptop and video batteries and in several other contexts. The so-called Smart circuit functions as time counter / power gauge on the battery.

A circuit board with microcontroller, etc. (BMS Battery Management System, SBS, the Smart Battery System) is built into the battery and accurately measures in- and discharged energy, temperature, number of cycles and others parameters.

The result is presented in the attached equipment display or monitor, and you can always see for example remaining capacity in percent or operating time in hours / minutes, in comparison with the earlier simple battery meter in the form of a few LEDs, bars in a small LCD display or the like, which pretty roughly showed the battery’s status. The information between the battery and external equipment can take different forms of a physical data bus, regular standard SM-bus, I2C bus, CAN bus and so on.

On larger battery systems, like for example electric vehicles or similar one often has many parts and modules, instruments, displays, motor control, etc. charging circuits , etc., that share data from the battery’s common communication bus. Components of batteries and cells can be split between master and slave modules , different manufacturers can use a little different names for the parts, BMS, BMU and so on.