Comparison Varta LCD Smart Charger + 4xAA 2100 mAh vs Extra Digital BM300

The battery technology that the charger is compatible with. Modern batteries can be manufactured using different technologies (Ni-Cd, Ni-Mh, Li-Ion, LiFePO4, IMR), each has its own characteristics and requirements for the charging procedure; therefore, for a specific battery, it is worth choosing a charger for which compatibility with the corresponding technology is directly stated.

— Ni-Cd. Nickel-cadmium batteries are one of the oldest types of rechargeable cells. Nevertheless, they are still used quite widely today — in particular, Ni-Cd batteries are considered optimal for devices with relatively high current consumption and increased reliability requirements. Such batteries are resistant to low temperatures, easy to store, reliable and safe. One of the main disadvantages of this technology is the “memory effect”: the battery capacity decreases after it is put on charge without being completely discharged. However, this point is more related to the features of charge controllers, and not to the technology itself, and the use of advanced controllers can be reduced to almost zero. But from the unambiguous shortcomings, one can mention the “non-environmental friendliness” of both the batteries themselves and their production.

— Ni-Mh. Nickel metal hydride cells were created in an...attempt to improve on the nickel cadmium cells described above. The creators managed to achieve a higher capacity (with the same battery size), in addition, Ni-Mh cells are environmentally friendly and completely devoid of the memory effect even when using the simplest charge controllers. The disadvantages of this option, compared with Ni-Cd, are relatively low resistance to frost, shorter service life and more difficult storage conditions, especially for long periods.

— Ni-Zn. A technology that is the same age as Ni-Cd and also survived to this day. Nickel-zinc cells are notable for their higher capacity than other "nickel" batteries, as well as higher voltage, which, moreover, remains at the operating level almost until the charge is exhausted. The latter is especially convenient for digital cameras — this technique is quite demanding on voltage. However, for a number of reasons, Ni-Zn technology has not gained much popularity. The main of these reasons is the short service life (about 300 – 400 charge-discharge cycles).

— Li-Ion. A type of battery, widely known primarily for portable electronics like smartphones or players, but has recently been successfully used in other types of equipment. Lithium-ion batteries combine good capacity with compactness, charge fairly quickly and are devoid of the "memory effect". Their main disadvantages are high cost, poor suitability for work at low temperatures and some probability of fire during overloads and failures.

— LiFePO4. A variety of the Li-Ion batteries described above, the so-called "lithium iron phosphate". The advantages of such cells over classical lithium-ion ones are, first of all, a stable discharge voltage (until the energy is exhausted), high peak power, long service life, resistance to low temperatures, stability and safety. In addition, due to the use of iron instead of cobalt, such batteries are also safer to manufacture and easier to dispose of. At the same time, they are noticeably inferior to lithium-ion in terms of capacity.

— IMR. This abbreviation is used for lithium-ion-manganese-oxide batteries, another variation on lithium-ion technology; the designation LiMn also occurs. Improvements introduced in this version include thermal stability (reduced risk of ignition in case of failure), durability and low self-discharge rates (the latter simplifies long-term storage). At the same time, many IMR batteries are claimed to be compatible with standard "chargers" for lithium-ion cells, but it is best to use specialized devices (in particular, due to low internal resistance and increased risk of overdischarging).

The battery sizes that the charger is compatible with. In this case, the adapters supplied in the kit (see below) are not taken into account in this paragraph, we are talking only about the memory as such.

The standard dimensions describes the shape, dimensions, connector design and operating voltage of the battery; thus, it is one of the most important parameters for determining compatibility with a particular charger.

The most popular sizes for which modern “chargers” are made can be divided into 1.5-volt (marked in Latin letters AA, AAA, C, D) and 3.7-volt (have digital markings 14500, 17500, 18650, 22650, 26650, etc. .P.). More about them:

— AAAA. The smallest version of the "finger" dimensions: batteries of the same cylindrical shape as the well-known AA and AAA, but with a size of only about 8 mm and a length of about 43 mm. Similar in application to AAA, but very poorly distributed.

— AAA. Size, colloquially known as "mini finger" or "little finger batteries": cylindrical batteries with a size of 10.5 mm and a length of 44.5 mm. They are mainly used in miniature devices for which there are not enough “tablet” bat...teries, and larger elements are too bulky.

— AA. Classic "finger" batteries with a size of 14 mm and a length of 50 mm, one of the most popular modern standard sizes (if not the most popular). They are used in a wide variety of types and price categories of devices, including even external battery packs for SLR cameras.

- C. Batteries in the form of a characteristic "barrel". They are similar in height to finger-type AAs, but almost twice as thick - 50 mm and 26 mm, respectively - due to which they have a higher capacity.

- D. The largest dimensions of consumer grade 1.5V batteries, 34mm in size and 61mm in length. It is mainly used in high-power flashlights and devices with high energy consumption.

3.7-V batteries are indicated by a five-digit number. In it, the first two digits indicate the size (in millimeters), the remaining three indicate the length (in tenths of a millimeter). For example, the popular dimensions 18650 corresponds to a battery with a size of 18 mm and a length of 65.0 mm. It is worth noting here that there are 3.7-volt cells that are the same dimensions as the 1.5-volt ones described above (for example, the 14500 dimensions is similar to AA finger-type), but both types are not interchangeable due to the difference in voltage.

A separate category is 9-volt R22 batteries, also known as PP3: these are rectangular elements in which a pair of contacts is located on one of the ends.

The smallest current that the device can provide in charge mode. If this parameter is specified in the specifications, this means that this model has the ability to adjust the charge current (otherwise, only the maximum current is indicated).

Charging current is one of the most important parameters for any charger: see “Maximum charge current. And the general range of current adjustment depends on this indicator: the lower the minimum value (with the same maximum) — the more extensive the possibilities for setting up the "charger" for the specific specifics of work.

The highest current that the device can provide when charging the battery (or the nominal value of the charging current, if it is not adjustable).

Charging current is one of the most important parameters for any charger: it determines the speed of the process and compatibility with certain batteries. In general, the higher the current, the faster the process, the less time it takes to charge. At the same time, some batteries may have recommendations for the optimal current strength and restrictions on its maximum values. Therefore, mindlessly chasing a powerful charger is not worth it: at first it's ok to clarify how justified such power will be.

Note that in multi-channel devices (see "Independent channels"), the maximum current strength can be achieved when only part of the channels are operating. The indicators provided when all channels are operating simultaneously are indicated separately for such models (see "Charge current (all channels)").

The highest current provided by a multi-channel charger (see "Independent channels") at full load, with all slots (and, accordingly, channels) operating. In fact, a guaranteed maximum current provided by a multi-channel charger, regardless of the number of channels involved.

For the total charge current, see “Maximum charge current. Here we note that the full load is a rather complex mode in which the current strength can decrease. Therefore, this parameter is specified separately.

The number of separate charge current settings (see above) provided in the design of the charger. For example, a device with 4 settings may provide options for 200, 400, 800 and 1000 mAh. In general, the larger this number, the more accurately you can choose the charging current for a particular situation.

The smallest current that the device is capable of providing in battery discharge mode.

Some specific functions are based on the discharge of the battery installed in the charger (see below for more details); in this case, it often becomes necessary to set a certain value of current strength, which is optimal for a given battery. The lower the minimum discharge current (with the same maximum) — the wider the adjustment range and the higher the probability that the device will be able to provide the optimal discharge mode.

The highest current that the device can provide in battery discharge mode.

Some specific functions are based on the discharge of the battery installed in the charger (see below for more details). The higher the maximum value of the discharge current, the less time it takes to “drain” energy from the battery. On the other hand, for some types of batteries and discharge modes, specific current recommendations may be provided, and exceeding them can be fraught with overload, overheating, and even fire. Therefore, it is necessary to specifically pursue high values of the discharge current only if it is justified from a technical point of view.

A function that prevents overcharging is the accumulation of an excess amount of energy by the battery installed in the charger. Overcharging is highly undesirable for any type of battery, and can lead to a variety of unpleasant consequences, from degraded performance to overheating and fire. To avoid this, chargers may be provided with automatic devices ( overcharge protection), which monitor the level of charge and automatically turn off the battery upon completion of the process.