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    About batteries

    The wireless freedom of our modern technology would be unthinkable without powerful rechargeable batteries. Whether smartphone, notebook, MP3 player, vacuum cleaner or drill machine, all these electronic devices feature state-of-the-art battery technology for reliable operation and a long service life. To ensure that this remains the case for a long time, the rechargeable batteries in the respective devices want to be charged and maintained correctly. But the battery variety is just as large as the device variety. And each battery wants to be treated and maintained individually. But if you observe some important basic rules, you will enjoy your batteries for a long time.

    • What is a battery?

    • What types of rechargeable batteries are there?

    • What standard battery types are available?

    • How are batteries charged correctly?

    • How do I treat batteries correctly?

    • Find the right battery

    • The most common questions about batteries

    What is a battery?

    A battery or accumulator is a secondary cell that can be recharged. Thus, rechargeable batteries can be used several times. When a battery is discharged, it must be recharged using a battery charger suitable for battery technology. Rechargeable batteries are particularly suitable for devices with hohem power requirements.

    Unlike rechargeable batteries, batteries are primary cells and intended for single use only. If a battery is discharged, it must be recycled. Batteries are suitable for devices that are only used once in a while, have a low power requirement and must be ready for use at all times.

    Unfortunately, the terms battery and battery are sometimes confused. Car batteries are also often used in automotive companies, but they are lead-acid batteries.

    Due to the ingredients, disposal of batteries and rechargeable batteries in the household waste is absolutely prohibited.

    Learn more about battery/rechargeable battery disposal

    What types of rechargeable batteries are there?

    In addition to the rechargeable battery design, which is usually specified by the device to be supplied, the rechargeable battery type or rechargeable battery technology is of decisive importance. Depending on the battery technology, different substances are used to build the rechargeable current storage.

    Lead-acid batteries

    The oldest and also the cheapest rechargeable batteries are still lead-acid batteries. These rechargeable batteries are available, for example, as lead-acid batteries, which are used in the automotive sector. Maintenance-free lead-gel batteries are tightly closed and can therefore be used in any position. These batteries are used in jump-start devices, UPS systems, alarm systems or also as solar batteries. For AGM or lead-fleece batteries, the diluted sulfuric acid is stored in a glass fiber fleece. The application range is identical to that of the gel batteries. In addition, they are also used as motorcycle batteries. 

    Lead-acid battery

    A closed lead-fleece battery with 12 V and 7.2 Ah.


        - cost-effective acquisition
    - high capacity values
    - robust

    - very sensitive to deep discharge

    To the lead-acid batteries

    NiCd batteries

    Until a few years ago, the nickel-cadmium battery was unbeatable in applications with extremely high power requirements, such as power tools and high-performance drives in model construction. In the meantime, however, this type of battery has already been almost completely replaced by the lithium polymer batteries.

    NiCd batteries

    Thanks to soldering tags, these NiCd batteries can be soldered together individually. 


        - more cost-effective acquisition costs than NiMH batteries
    - for extremely high power requirements and fast charging
    - very cold-proof

    - must be discharged completely regularly before charging.

    Note: There is a general ban on sales due to the toxic heavy metals. Only NiCd rechargeable batteries for cordless power tools, emergency and alarm technology as well as medical technology are excluded.

    To our NiCd rechargeable batteries

    The memory effect

    NiCd batteries have an amazing memory
    , so-called memory effect makes even the strongest battery weak. Therefore, always charge a nickel-cadmium battery when it is completely discharged. Otherwise, cadmium crystals may form on its negative electrode. The battery remembers this incomplete discharge state and saves it as empty. In fact, there is still capacity below this discharge level - only it can no longer be used. Further incomplete discharge cycles will then decrease the performance. To avoid this memory effect, you should discharge NiCd cells once in a while. This considerably extends the service life of the rechargeable batteries.


    NiMH Rechargeables

    Nickel metal hydride batteries (NiMH) are characterized above all by their environmental friendliness. You can store more energy than NiCd batteries and do not suffer from the memory effect. As a result, NiMH round cell batteries are widely used and very popular with users.

    NiMH Rechargeables

    NiMH rechargeable batteries in different designs and designs.


       - free of toxic heavy metal cadmium
    - offers a higher capacity -
    no memory effect - with the same design

    - higher acquisition costs than NiCd batteries
    - more sensitive to cold than NiCd batteries
    - more discharge when charged for a longer period of time (except for a NiMH battery with low self-discharge such as Conrad Endurance, Sanyo eneloop or Varta Ready2Use)
    - used charger must be designed for NiMH batteries

    To NiMH rechargeable batteries

    NiZn rechargeable batteries;

    The nickel-zinc battery (NiZn) is the ideal solution if devices with NiMH batteries do not work or only function inreliably due to the low voltage of 1.2 V/cell.

    Nickel-zinc batteries with 1.6 V/cell offer more voltage than batteries.

    - high voltage of 1.6 V/cell
    - high energy density and cycle stability
    - very cold-proof

    - Charger must be designed for NiZn batteries.

    To our NiZn micro rechargeable batteries
    To NiZn AA rechargeable batteries

    Li-ion or LiPo batteries

    As a proven power supply for mobile phones, smartphones, notebooks and digital cameras, high-capacity lithium batteries are now also used as lightweight drive batteries in the model construction sector. However, lithium batteries are still relatively expensive and may only be recharged with special chargers. Exceeding the maximum charging voltage can easily destroy lithium batteries.

    Li-ion or LiPo batteries

    Despite its compact design, lithium batteries provide high capacities.

    - high voltage of 3.6 - 3.7 V/cell
    - high energy density
    - different designs available

    - Chargers must be designed for lithium batteries.

    To our Li-Ion batteries
    To the LiPo rechargeable batteries

    What standard battery types are available?

    N size AAA
    rechargeable batteries
    AA rechargeable batteries 
    Most small electronic devices (e.g. Remote controls, clocks, compact pocket lamps or scales) can be equipped with Lady, Micro or Mignon batteries in variable number. Due to the low power consumption of the devices to be operated, these battery sizes still offer sufficiently long operating times.
    Size C rechargeable batteriesSlightly larger than AA batteries, Baby (C) batteries have significantly higher capacities. They are preferably used in devices, such as children's toys, which have an increased power requirement.
    Size D rechargeable batteriesAs the largest round cell battery, the mono battery is mainly used in powerful devices such as portable radios or torches. The high capacities of these batteries guarantee long operating times.
    9V RechargeablesFor some special devices 9 V block batteries are required. They are made up of several small individual cells that can be placed in the housing of the block battery. 9 V battery packs are often used in measuring devices.
    Battery PacksBattery packs are particularly popular in model construction as a practical energy storage unit with high capacity. Due to the almost limitless combination possibilities, individual batteries can be put together for each application area.

    Sometimes there are different names for the different battery sizes:


    HR1, 50NH, N, LR1, LR01, E90, LR1-N, LR1/E90, 4001, AM5, KN, MN9100, MN9100/N, UM5, R1, KN-2, 810, 910A, L1129


    HR3, HR03, UO100557, DC2400, DC2400B4N, LR03, AAA, LR3, AM4M8A, AM4, S, MN2400, 824, E92, LR03N, 24A, K3A, R3, R03, 7526, UM4, MINISTILO, V2500PX


    HR6, HR06, CEF80, RB104358, LR06, AA, LR6, AAB4E, AM3, M, MN1500, 815, E91, LR6N, 15A, KAA, R6, R06, BA3058, U7524, UM3, STILO, V1500PX


    HR14, LR15, C, AM2, L, MN1400, 814, E93, LR14N, 14A, KC, R14, BA3042, U7522, UM2, 1/2 TORCIA

    D cell

    HR20, LR20, D, AM1, XL, MN1300, 813, E95, LR20N, 13A, KD, R20, LR20L, BA3030, U7520, UM1, TORCIA

    9V block

    HR6F22, HR9V, HR22, 6LR61, 6LR21, 6AM6, 6LP3146, MN1604, A1604, E BLOCK, LR22, 522, 6LF22, 1604A, K9V, 6R21, 6R22, BA3090/U, 6F22, PP3HP, 006P, AM6F, 6LF62, HP3, M1604, 4022, BLOC, CLR6, KA9, ND65V, U9VL-J-P.

    How are batteries charged correctly?

    Lead-acid batteries

    An empty lead battery can draw an extremely high current. For this reason, the charging current must be limited at the start of charging for high-capacity lead-acid batteries. This limitation can be achieved either by the maximum capacity of the charger or by an electronic current control. The charge current should correspond to approx. 1/20-1/10 of the capacity value. For a rechargeable battery with 16 Ah, the charging current would be 0.8 - 1.6 A.

    First, the voltage increases steeply until the set charging current flows (t1). During the charging process, the charging voltage will continue to increase at the same current until the maximum permissible voltage is reached at t2. Now, the charging current will continue to decrease at the same charge-end voltage. If the current falls below a minimum (t3), the lead accumulator is fully charged. 

    Lead-acid battery charging curve

    Typical charging curve of a lead-acid battery

    NiMH Rechargeables

    NiMH batteries are charged with a constant current. If the charging current can be set manually, it should be approx. 3/10 of the capacity value. For a rechargeable battery with 2000 mAh, the charging current would be 600 mA. With quick chargers, the height of the charging current is determined and controlled automatically on the basis of the battery behavior. The voltage then increases very quickly until the required charging current flows (t1).

    The detection of when the battery is fully charged is done by means of the charging voltage curve. This forms a typical Höcker at the end of the training. Although energy is still being charged into the battery, the charging voltage (t2) decreases. The detection of negative voltage change is called minus Delta U- or minus Delta Peak disconnection. The higher the charging current, the stronger the voltage drop is pronounced.

    NiMH charging curve

    After switching off the charging current, short-term current pulses ensure that the charging of the battery is maintained.

    Lithium rechargeable batteries

    Lithium batteries are charged according to the same procedure as lead-acid batteries. A defined current flows at the start of charging until the maximum permissible charging voltage is reached. The current then decreases with the same voltage. If the minimum value is undercut, the charger switches off.

    However, the voltage values per cell vary depending on the cell chemistry. In addition, the maximum charging voltage per cell must be maintained absolutely exactly. With multi-cell lithium batteries, balancer electronics are used to keep all cells of a battery pack at the same level.

    Depending on the application, the balancer electronics are either installed directly in the battery pack or in the device. For drive batteries used in model construction, the balancer electronics are usually integrated in the chargers.

    In some cases, individual cells are also provided with protective circuits so that the charging voltage is not exceeded.

    Lithium single cell with protective circuit.


    Only charge rechargeable batteries with the charger, which is also designed for the respective rechargeable battery. Ideally, the manufacturers will supply suitable charging cables or chargers to the respective products. In this case, only the charging options specified by the manufacturer should be used.

    If, for example, a Li-ion battery is charged with a charger that is only designed for NiMH battery packs, there is a high risk of fire and explosion!


    How do I treat batteries correctly?

    Lead-acid batteries

    For a lead-acid battery, it is not useful for the service life if it is discharged more than 50%. Even if it is then fully charged again. The specialist speaks of a deep cycle here. For a lead-acid battery, it is much better to recharge the removed capacity of, for example, 10 – 15% immediately. In this case, a flat cycle is referred to.

    This is exactly what happens with a car battery or a car lead-acid battery. Even if the starter requires a very high current for a short time, the capacity taken during a start-up process is only minimal. And the alternator charges the battery immediately when the engine is running. Thus, a car battery manages tens of thousands of start-ups without taking any damage.

    Lead-acid batteries for solar systems or electric vehicles are forced to operate in cycles. For this reason, they are constructed and constructed differently according to these tasks.

    Lead-acid battery

    Proper care is important not only for large and expensive rechargeable batteries.

    Lead-acid batteries must be checked and maintained regularly. Liquid loss must be compensated for by distiled water. For optimum level, these batteries often have markings on the side or in the filling openings. If these marks are missing, the optimal acid level must exceed the top edge of the lead plates by approx. 1 cm.

    Lead-acid batteries that are not used during the winter should be fully charged before storage. In addition, the rechargeable batteries should be recharged regularly. Alternatively, chargers with a maintenance charging function can also be used.

    NiMH Rechargeables

    NiMH rechargeable batteries are relatively easy to maintain and can easily remove deep discharge. Long-term charging, on the other hand, can significantly shorten the service life and performance of the batteries. For this reason, it is not recommended to store e.g. the cordless telephone in the charging cradle 24 hours a day.

    However, NiMH batteries suffer from a certain self-discharge. Therefore, you should always recharge the battery before use. Some manufacturers have detected the problem and offer NiMH batteries with low self-discharge. These batteries are sold under the names Conrad Endurance, Pamasonic eneloop or Varta Ready2Use.

    Ready to use rechargeable batteries have a very low self-discharge.

    Lithium rechargeable batteries

    What was used to make lead-acid batteries last longer is highly harmful for lithium batteries. This is the aim of keeping the battery at a charge level of 100%.

    Model makers have been practicing it for a long time and only recharge their large and expensive LiPo batteries up to 70% after the last use. This optimally protects the high-quality rechargeable batteries during the rest period until the next use in the model.

    The owners of notebooks, laptops, netbooks or tablets should consider this as far as possible. Often, the batteries in the devices are kept at 100% charging status with the help of docking stations or charging cables when stationary at home or in the office. After a few years, you will find that the notebook still works well, but the battery life is very short.

    This is true for smartphones. But until the battery shows the first signs of fatigue, there is already a successor model from the phone. A weakening battery is often the decisive argument for getting a new smartphone. 


    When properly maintained, notebook batteries will last significantly longer.

    Find the right battery

    For round cell batteries, the purchase decision is relatively simple. The design AA, AAA, C, 9V block or D plays a decisive role. The batteries with the same design then differ only by the brand and the capacity data in mAh. Only in rare cases will NiZn batteries with 1.6 V/cell, instead of NiMH batteries with 1.2 V/cell, be required.

    In lead-acid batteries,… the technology (acid, gel, fleece, etc.) is the main focus of the technical data. Apart from voltage and capacity, the dimensions and, of course, the connections with flat plug, M6 screw connection etc. are also decisive. Some applications, such as alarm systems, require VDS certification.

    Lithium batteries are becoming more difficult. This is where the buyer has to define everything from the technology (lithium polymer, lithium iron or lithium ion), the design, the connection up to the number of cells and the dimensions. The weight of the rechargeable battery is then also decisive for model flyers. 


    The most common questions about batteries

    How often can I charge a battery?

    The number of charge cycles for rechargeable batteries depends on the technology and the discharge depth. In addition, it is also crucial how well the battery is treated. While lead and lithium batteries are very sensitive to deep discharge, NiCd batteries should be discharged before charging to keep them efficient.

    How fast is a battery charged?

    The speed at which a battery can be fully charged depends on the battery. The manufacturers indicate the maximum permissible charging current for the technical data. The charger must then be able to provide this. Rapid charging with maximum charging current should only be carried out if the rechargeable battery is urgently needed. As a rule, slower charging processes are more gentle for the rechargeable batteries. 

    What was the meaning of the mAh? 

    The specification indicates the capacity of a rechargeable battery. The capacity indicates how much electrical energy a battery can store or how long it can deliver a certain current. A nickel metal hydride rechargeable battery type AA Mignon with 2000 mAh can draw a current of 200 mA over a period of 10 hours. If the discharge current is increased, the usable capacity is reduced.

    Why do batteries of the same type often differ in capacity?

    The capacity value only indicates how much energy a battery can store or deliver. However, he does not say anything about the quality and performance of a battery. Often, high capacitance values are achieved at the expense of other parameters such as internal resistance or self-discharge.   

    What was a high-current battery?

    As the name suggests, these batteries can be charged within a very short time and discharged in a very short time. High-current-capable batteries are gladly used for the power supply of electric models. Even if the motor run times are only a few minutes, a tremendous power is available during this time.

    How to dispose of a battery?

    Rechargeable batteries must not be disposed of in household waste due to the metals and acids used. They can be delivered (such as batteries) to recycling yards or dealers for professional use.

    What was a rechargeable battery?

    A rechargeable battery was an alkaline battery, which could be recharged to a limited extent. However, special chargers were required for this. With this system, the manufacturers tried to combine the advantages of a 1.5 V rated battery and the reusability of a battery. Since the introduction of the 1.6 V rated NiZn batteries, rechargeable batteries have lost importance. 

    What was it that smelled uncomfortable when charging a camper battery?

    The unpleasant smell is hydrogen sulphide. This occurs when lead-acid batteries become overcharged and too hot. The cause can be an unsuitable or defective charger (charging voltage too high) or a defective battery.
    In addition, lead-acid batteries can be gases during charging. This produces a highly explosive mixture of oxygen and hydrogen (blast gas), which escapes through the filling openings. Therefore, large lead-acid batteries should only be charged in well ventilated rooms.
    Important: When charging rechargeable batteries, always comply with the limits for current and voltage specified by the manufacturer.