A lead battery is composed of various grids and plates, among other things.
Seriously good: Lead batteries from LEAB
Batteries are important energy storage devices in mobile power supply and come in different varieties. Lead batteries have been in use for more than 100 years, including in the field of mobile power supply. Today, they are the most widely used batteries in the automotive sector. We present the three most important types.
Lead batteries - what are the different types?
There are several types of lead-acid battery, which differ in terms of their construction and application. These are the three main types:
Wet batteries: These are the traditional lead-acid batteries that contain a liquid electrolyte. They are often used as starter batteries for vehicles and are also found in other applications.
Gel batteries: In these batteries, the electrolyte is bound in gel. The gel technology makes the batteries particularly resistant to vibrations and shocks. Gel batteries are maintenance-free, found in applications with high demands on reliability and long service life, and offer lower self-discharge compared to wet and AGM batteries. They are particularly well suited for recreational use and emergency power supplies.
AGM batteries: AGM stands for Absorbent Glass Mat, which means that the electrolyte solution is absorbed in a glass fibre material placed between the lead plates. AGM batteries are maintenance-free, have a long cycle life and are often used in vehicles with automatic start-stop and/or brake energy regeneration.
Plus and minus: Advantages and disadvantages of the three lead-acid battery types
Advantages of conventional wet batteries
Price: Conventional open lead-acid batteries are the most commonly used and are particularly inexpensive.
Service life: Regular maintenance and care can extend the service life, especially in unfavourable temperature conditions. Used water can be refilled before damage to the plates occurs. By spinning out the acid density, the state of charge of each individual cell can be determined very precisely.
Readily available: Should a replacement battery be needed, lead-acid batteries can be found at almost any petrol station and DIY store.
Disadvantages of conventional open wet batteries
Charging cycles: Open lead-acid batteries usually have a lower number of usable discharge cycles - especially if they are not specifically designed for cyclic discharge. Most lead-acid batteries are sold as starter batteries and cannot be used as auxiliary batteries.
Low capacity: Lead-acid batteries can be discharged less deeply and therefore have less usable capacity than other types of batteries. In practice, you should discharge no more than 50 % of the nominal capacity to avoid damaging deep discharge.
Maintenance: The acid level of open lead-acid batteries must be checked and replenished regularly.
Safety: During charging, traces of battery acid, which are highly corrosive, escape through the vent holes in addition to explosive hydrogen-oxygen mixture. Open lead-acid batteries must therefore not be installed directly in the interior and must be provided with a vent to the outside. If the housing is damaged, lead-acid batteries may leak liquid sulphuric acid, which is corrosive and can cause injuries.
Advantages of gel batteries
Maintenance-free: Gel batteries do not require maintenance as they are sealed and no water needs to be refilled. This saves time and effort compared to other types of lead-acid batteries.
Safety: Due to the sealing, gel batteries are safer than conventional open lead-acid batteries. Even if the housing is damaged, no gas or acid can be released. This also makes them suitable for use in closed environments.
Low self-discharge: Gel batteries have a low self-discharge rate. This means they can hold their charge for a long time without being recharged. This is particularly beneficial for applications where the battery is not used regularly.
Service life: Gel batteries have a very high cycle life, they can be charged and discharged frequently without affecting the battery life. Since gel batteries can be discharged deeper than wet batteries, they have a greater usable capacity with a comparable nominal capacity.
Disadvantages of gel batteries
Price: Gel batteries are generally more expensive than conventional open lead-acid batteries.
Charging technology: Gel batteries are less tolerant of overcharging as the lost water cannot be replaced and as a result the plates can dry out. You should therefore always choose a suitable charger with an appropriate charging programme.
Advantages of AGM batteries
Service life: AGM batteries can be charged and discharged very frequently without affecting battery life. Because they can be discharged deeper, AGM batteries also have a greater usable capacity than wet batteries, for example.
Maintenance-free: AGM batteries require no maintenance as they are sealed and no water needs to be topped up. This saves time and effort compared to other types of lead-acid batteries.
Low self-discharge: AGM batteries have a low self-discharge rate. This means that they can hold their charge for longer periods of time, which is particularly beneficial for applications where the battery needs to last for longer periods of time without recharging.
Safety: AGM batteries are sealed, which means that no gas or acid vapour escapes during charging. Even if the housing is damaged, no gas or acid can be released. This also makes them suitable for use in closed environments.
Robustness: Because the lead plates are separated by means of fleece mats, AGM batteries are more robust than lead-acid batteries and are sometimes even used in construction machinery such as vibratory plates.
Disadvantages of AGM batteries
Price: AGM batteries are usually more expensive than conventional lead-acid batteries.
Charging technology: AGM batteries are less tolerant of overcharging because the lost water cannot be replaced, thereby reducing performance. You should therefore always choose a suitable charger with an appropriate charging programme.
How does a lead-acid battery work?
A lead-acid battery operates based on the electrochemical reaction between opposing lead plates and a diluted sulphuric acid - the electrolyte - in which the lead plates are immersed.
When charged, the positive electrode (plate) consists of lead sulphate and the negative electrode of pure lead. When both electrodes are connected outside the battery by a consumer, the chemical reaction in the battery begins. While the electrons move through the load from one battery pole (negative pole) to the other (positive pole) and current flows, ions in the battery move from the positive electrode to the negative electrode to compensate. This also produces lead sulphate on the negative electrode. This reaction consumes the sulphuric acid and the concentration of the electrolyte solution decreases.
Limited useful life
When the concentration of sulphuric acid has fallen below a certain level, the battery must be recharged. During charging, the chemical processes run in reverse order until the original state is restored at the end. Since this conversion process is characterised by losses, each lead-acid battery can only survive a limited number of charging cycles. Its useful life is therefore limited.
Here, too, there are design-related differences that are decisive for the selection of the intended use. Starter batteries, for example, often only have 100 to 200 charging cycles, while high-quality gel batteries can achieve ten times that. In practice, the service life of a battery is determined by the depth of discharge used. The deeper and more regularly the battery is discharged, the lower the number of cycles that can be achieved.
Which battery is appropriate for a particular purpose?
The choice of the appropriate battery type always depends on various factors, such as the application, the number of cycles, the required capacity, the operating temperature or the environmental conditions.
However, which battery is more suitable for a particular application (starter battery or auxiliary/consumer battery) depends less on the design than on the geometry of the installed plates. Starter batteries which have to deliver very high currents in the short term, contain a relatively large number of thinner plates with a correspondingly large surface area. Batteries for utility applications, on the other hand, consist of fewer plates overall. However, these are thicker and therefore have a smaller surface area for the same capacity. These relationships essentially apply to all battery types, whether wet, gel or AGM. In practice, gel batteries, for example, are found more often as auxiliary batteries than as starter batteries, as the bonded electrolyte offers additional advantages that can be put to good use.
It is best to contact our technical sales department to determine an exact estimate of your needs. At LEAB we offer all types of lead-acid battery.
