Accumulator? Battery? What is right and what are the things that will make the difference later?
A battery is an electro-technical energy storage on an electrochemical basis. In the past, battery and accumulator cells were clearly differentiated into non-rechargeable (primary cells) and rechargeable (secondary cells). Fortunately nowadays there are almost only batteries that are rechargeable. But there are still many differences here, which we will try to explain in more detail here.
Lithium batteries
PRO
The lithium battery impresses with its long service life, no memory effect, low self-discharge rate while being stored, very high energy density, for example a lithium-ion battery can provide the same capacity compared to a lead battery with only half the weight. The number of charging cycles is also significantly higher compared to a lead battery. The purchase price of a lithium battery therefore pays for itself in no time. The so-called BMS (Battery Management System) ensures that the individual cells are monitored in the state of charge as well as in the state of discharge and, if necessary, intervene in the charging or discharging process and stops it.
CONTRA
The biggest shortcoming of a lithium battery is the so-called "deep discharge", if this occurs, the battery is very likely irrevocably damaged and can hardly be saved. The negative consequences of deep discharge are irreversible.
Very low or too high temperatures cause problems for the battery and the cells inside get into so-called "stress". The optimal operating temperature of a lithium battery with regard to its optimal service life is 22 ° C.
Lead-acid batteries
PRO
Lead-acid batteries are still installed in almost every car, motorcycle, truck and easily fulfill your task as a starter battery. The lead-acid battery is also a good solution when it comes to value for money. It can deliver high currents in a short time and (provided good maintenance and care is required) is also one of the most economical solutions with regard to its service life.
CONTRA
Lead acid batteries have a very low energy density. This means that, based on its weight, the lead battery is about twice as heavy as a lithium-ion battery. In addition, a lead battery must not be operated upside down and only to a limited extent in the lateral position.
Amount of energy (Wh)
The energy is given in watt hours (Wh). It is calculated from the formula capacity times voltage (Ah x V = Wh). If you divide the amount of energy, by the power consumed by the device, the approximate runtime results.
Capacity? What's this?
The capacity is the amount of stored electrical energy. For a battery, the capacity indicates how much electricity the battery can store or deliver. The capacity is usually given in milliampere hours (mAh) or ampere hours (Ah).
A battery with 1 Ah capacity can deliver a current of 1 ampere for one hour.
If the battery only has to deliver half an ampere, the capacity is sufficient for 2 hours of runtime or at 2 amps for half an hour. Conversely, the higher the current drawn, the shorter the runtime.
How is the capacity of a battery measured?
Unlike the voltage in volts or the current flowing current, the capacity cannot be measured directly and immediately.
In order to be able to measure the current capacity of a battery, it must be measured in a process of charging, discharging and recharging with cooling phases in between under load. Depending on the target capacity of the battery to be tested, this process takes several hours to an entire day. The measurement process can be accelerated by increasing the charge and discharge currents and shortening the cooling phases - but this irreversibly leads to large errors in the measurement result.
How do you calculate the range of a battery?
There is no reliable value for the possible range that can be driven with one battery charge. The range specifications are therefore always only maximum guidelines that can be achieved in the best possible case. The possible range depends on the one hand on the power consumption of the electric motor, which is subject to extreme fluctuations due to the distance traveled, payload, tire pressure, wind conditions, route topography, etc., and also in key figures for the battery itself, such as age, condition, charging behavior, etc.
What should therefore be used as a fixed value for determining the theoretically possible range is the capacity in Wh or Ah. This is a fixed value which is measurable (comparable to the volume of a tank of a gasoline-powered car). If the tank is empty, the vehicle stops - if this time you are driving with one person and an empty trunk, the route is of course much longer because less fuel consumption than with a fully occupied car with the trunk full of luggage and a trailer. This is where fuel consumption skyrockets and the range can be dramatically reduced.
Charging and discharging?
There are three voltages that are important for a battery. That would be the nominal voltage (lead acid battery 12 V), the charge voltage, which must not be charged beyond (lead acid battery 13.8 V) and the max. discharge voltage, which must not be discharged further, otherwise damage could result. This would be 10 V for a lead-acid battery. All voltage information relates to one battery cell. Switch-off electronics are installed in some batteries, this protects against deep discharge.
Wear caused by charging / fast charging
The higher the charging current, the greater the wear inside the cells. There are many so-called fast chargers on the market - the advantage of this is that, as the name suggests, the charging time is sometimes drastically reduced. This is made possible by high charging currents of up to 10A in some cases. However, this leads to thermal and chemical "stress" inside the lithium cells, which in turn leads to increased wear and thus a shorter service life.
The commonly used charging currents are 2A - all chargers with higher performance could be called "fast chargers". The permissible max. charging currents of battery cells are different and one should consider the max. charging current never exceed the values specified on the type plate or data sheet of the battery in order not to damage it.
Deep discharge - what does that mean?
Depending on the battery technology, each battery cell has a max. discharge voltage. If this falls below, one speaks of deep discharge. The greater the shortfall, the more negative this has a direct impact on the battery condition and its service life.
Lithium batteries are extremely sensitive to this deep discharge state and are in most cases irrevocably damaged or even destroyed. Lead-acid batteries are generally more robust and more forgiving than deep discharge, but they too, like the lithium cells, are irreversibly damaged and weakened up to the point of total cell failure.
Facts, lifespan, care, storage
Lithium batteries
A lithium-ion battery loses capacity over the course of its life due to aging. In addition, charging cycles and the power demanded by the battery affect the service life - in other words, every charging and discharging cycle. Chemical processes inside the battery wear out more and more. Extreme temperatures in the plus or minus range can damage the chemical components of a battery as well or contribute to greater wear. Optimally, a lithium battery is never 100% charged and also never completely discharged - the optimal range here is between 30-80% - this is where the battery feels most comfortable and thanks you with the longest possible service life.
The operating temperature plays a very important role in terms of performance. It should not be too low, but also not too high - if this is the case, the performance of the battery will decrease or, in the worst case, damage it. If the temperature is too low, the internal resistance of the battery increases and the voltage drops, making it harder for the battery to provide the energy it needs, which also reduces the range. If the temperature is too high (from 35 degrees Celsius), the battery has to use a lot more energy to deliver the same power - here too the range decreases. The aging process of the battery is also accelerated by heat, which can result in a loss of range and the total number of charging cycles. The ideal operating temperature is 22 ° Celsius. The optimal storage temperature for lithium batteries is 10° C - always cool and dry. It is important not to leave the battery to itself during storage, but to check it once a month and ideally to keep it at a charge level of around 50%.
Lead-acid batteries
During the discharge process of a lead acid battery, sulfate crystals form on the inside of the lead plates - this is a normal process. Due to the increasing voltage due to recharging, these crystals are simply dissolved again. However, this is never 100% - that means that something of the crystal always remains "left over". In the course of his life, more and more sulfate crystals collect on the surface of the lead plates, which more and more complicate and hinder the flow of energy. At some point, the “number” of these sulfate crystals increased so that there was no longer any significant current flow - then one speaks of the wear limit of the lead acid battery and this has to be replaced by a new one.
It applies - the lower the voltage and the longer a lead battery is operated or stored at low voltage, the more the sulfate crystals “grow” on the surface of the lead plates. If these have grown extremely long & large (e.g. due to long pauses during two recharging processes), this process cannot be reversed even by charging and one speaks of a sulfated battery, which then means the so-called "deep discharge" of a lead battery. Even then, it can only be replaced with a new one.
We recommend 15 ° C as the optimal storage temperature for lead acid batteries - always cool and dry. It is important not to leave the battery to itself during storage, but to check it once a month and optimally to keep it at a charge level of around 90% - i.e. in the upper rather than the lower voltage range.