Nickel-cadmium, nickel-metal hydride or lithium-ion? Or maybe it's better to buy a lithium polymer battery? And what longer does it work? And with which less hassle? Having heard, Motorola has developed some new fuel cells in which something is flooded. Accidentally not gasoline? Question, question, question ...
Let's try to sort out the order.
types of batteries
To date, batteries for the following electrochemical systems are most commonly used to power mobile devices, portable computers and equipment: sealed lead-acid (SLA), nickel-cadmium (NiCd), nickel-metal hydride (NiMH) and lithium-ion (Li- ion) Gradually begin to gain positions in the field of cellular phones and portable computers lithium polymer (Li-Pol) batteries. There are developments in the field of fuel cells and some other promising technologies for the manufacture of batteries.
The specifications of the main types of batteries are listed in Table 1, with the permission of Landata.
Notes:
With the correct and regular service, the number of duty cycles charge / can be 4000 instead of 1500 cycles guaranteed by the manufacturer. Without conducting training cycles, the number of work cycles can be reduced by more than three times.
The number of operating cycles depends on the depth of discharge. Low bit depth provides more cycles.
Self-discharge is virtually stopped for the second day after the full charge of the battery. Self-discharge of NiCd batteries is 10% during the first 24 hours, then falls to 10% per month. Self-discharge increases with increasing temperature.
Built-in battery protection circuit consumes about 3% per month.
1.25 volts - the value of the voltage of one element, 1.2 volts - is often found in the literature and descriptions. Both values ??refer to one element type.
2.5-3.0 volts, depending on the material of the positive electrode.
Relevant only to the category; the temperature range of the charge is more limited.
The cost is for 1999.
Each type of battery has certain advantages and disadvantages. Let's consider both those and others more.
SLA batteries
Scope - Uninterruptible Power Supply Units (UPS), alarm systems, railway automation and communication devices, wheelchairs, backlighting. Previously, these batteries were equipped with some models of portable handsets and camcorders. On the whole, we can say that SLA batteries are commonly used in cases where high power, minimal cost, and size and weight are not critical. The range of capacitance values ??for portable devices ranges from 1 to 30 A · h. Since these batteries are currently not practically used in modern mobile devices, I am sending anyone interested in SLA batteries.
NiCd batteries
Field of application: cellular telephones, conventional and trunk radios, home radios, portable computers, camcorders, hand-held power tools, medical devices, various manufacturing equipment. New models of cell phones and laptops with these batteries are no longer complete. But trunk and conventional radio stations are still widespread.
Excellent advantages.
Fast and easy charging method. The NiCd battery allows a charge with a current equal to its nominal capacity and more. So, it's really possible to charge the battery in one hour. And if you suddenly need an even faster charge, you can use the charge current twice and three times the value of the nominal capacitance. But you should not abuse this. In addition, when a fast charge requires the use of special chargers that determine the moment of full charge of the battery and stop fast charge.
For them, the best pulse method of charge compared with the charge of direct current. Improved efficiency is achieved by distributing pulses of discharge between charge pulses. This charge method, commonly referred to as reversible, supports a high area of ??the active surface of the electrodes, increasing the efficiency and lifetime of the battery. The reverse charge also improves the fast charge, t. K. Helps recombination of gases emitted during the charge. As a result, the battery is less heated and more efficiently charged compared to the standard DC charging method.
The ability to give a load of large current
Long service life under conditions of operation and periodic service.
Weak sensitivity to improper operation, easy recovery with reduced capacity and after prolonged storage (from 60 to 70% of batteries declared to be unsuitable can be restored for full operation). The recovery of the battery is realized by its discharge according to a special algorithm up to 0.4 volt voltage per element. The recovery cycle is used if the training cycles do not help.
Low price.
Disadvantages
The need for periodic maintenance to eliminate the "memory effect". Under the "memory effect" is the enlargement of the crystalline formations of the working substance of the battery and, consequently, the decrease in the area of ??the active surface and the actual capacity of the battery. Under maintenance (training cycles) refers to a periodic discharge of batteries to a voltage of 1 volt per element, which results in the decoupling of crystalline formations and increase the actual capacity of the battery.
High self-discharge (up to 10% during the first 24 hours and up to 20% in the first month after the charge).
Large dimensions and weight compared to other types of batteries.
The battery contains cadmium and requires special recycling, so in some countries for this reason it is already forbidden to use.
NiMH batteries
In the recent past, NiMH batteries have replaced NiCd. However, their noisy advertised benefits did not ensure 100% satisfaction of user queries, mainly due to shorter service lives.
Characteristic features of NiMH batteries.
The electrical energy density is approximately 30-50% higher than that of NiCd batteries and, accordingly, is less than the size and weight.
For them the best is faster superficial than a deep discharge and the term of their service is directly related to the depth of discharge.
NiMH batteries, in comparison with NiCd, provide much more heat during charging and require the implementation of a more complex algorithm to detect the moment of full charge. As a rule, they contain an internal temperature sensor to obtain an additional criterion for detecting a full charge.
The NiMH battery can not be charged as fast as NiCd. The charging time is usually twice as high as that of the NiCd. The recommended discharge current is one to five times the nominal capacity.
Less propensity to the "memory effect" (you can even say that the battery just does not have time to buy it).
Ecologically clean manufacturing technology.
Small number of charge / discharge cycles.
High self-discharge (up to 30% per month).
Li-ion batteries
Scope: cell phones and all sorts of portable computers. According to experts from Varta corporation, Li-ion batteries will soon supplant not only NiCd, but also NiMH batteries from this market. Structurally, this type of battery contains an internal control and protection circuit, designed to limit the peak voltage of each element during the charge and prevent the voltage drop of the element at a level below the permissible level. In addition, in order to ensure the safety during their operation, the maximum charge and discharge current must be limited and the temperature of the element must be monitored.
Excellent advantages.
High density of electric energy, small dimensions and weight.
Low self-discharge (about 3-5% in the first month, then decrease to 1-3% per month, an additional about 3% per month consumes the control scheme).
Lack of any service during the entire lifetime.
Disadvantages
The high price.
Necessity of storage in a charged state.
The tendency of the aging process, even if the battery is not to be used. The deterioration of the capacity is observed after about one year from the time of manufacture. After two years, the battery often becomes faulty. It is not recommended to store Li-ion batteries for a long time. Enjoy them while they are new.
I would like to note that due to the different voltage of single elements of accumulators based on nickel and lithium-ion batteries (1,2 and 3.6 volts, respectively), replacement of one on another is not always possible. For example, cell phones with a voltage of 4.8 volts. In addition, these batteries require different types of chargers.