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17.01.2022

The profitability of your investment is determined by service life

A clear profile of requirements, combined with knowledge of what is technically possible at the time, will help vehicle operators to assess the major differences between lithium ion energy systems presently available.

For many years now, lithium ion batteries have already been put to good use in many applications. This applies as much to motive power as it does to the interim storage of power produced regeneratively from solar cells. Experience gained in recent years teaches us that the financial success of any investment will hinge essentially on service life and the amount of energy that can be gained in one charge/discharge cycle; system availability is not the only criterion.

Consequently, we need to categorise and investigate with a critical eye, looking firstly for cost effectiveness – and the service life of the various system options – whenever we are considering investing in lithium powered systems for in-house movements of goods. So, what are the specific requirements and precisely what are the distinctions to be drawn? And what – in detail – are the corresponding repercussions?

In this article, we look into these topics, and we’ve consulted a specialist in this field, Mr Peter Höptner, the traction distribution manager of BENNING to help us appreciate the distinctions to be drawn – and the all-important details.

Aspirations and Objectives

Firstly, let’s review the current market situation and take a good close look at the aspirations and objectives of our customers, the operators of the corresponding powered systems. We’re talking about: ROI, adaptability and guidelines for operation. At the end of the day, that must be how manufacturers compare the requirements to be fulfilled, depending on their clients’ systems, which is how people arrive at a soundly-based investment decision.

Cost-effectiveness, flexibility, connectivity

As you would inherently expect when it comes to a corporate investment, one of the top priorities is going to be a rapid ROI (Return on Investment). In that light, low operating costs, manageable maintenance and servicing intervals together with fault-free (and interruption-free) operation will be high on the list. It’s equally important to offer versatility with regard to the connnectivity of systems, such as when it comes to integration into a company’s own energy management systems, together with the simplest and most straightforward access to the essential battery and charging-system parameters.

Second life, CO2 Footprint, Recycling

liflex classic

robust, reliable battery, 24 V to 48 V, 120 Ah to 480 Ah.

liflex ng frontview
liflex NG
innovative, future-proof, modular, quick-charging capability, fulfils DIN EN 1175, 24 V to 120 V, 140 Ah to 700 Ah.
longevity ensured by Q-Leveling

liflex NG

innovative, future-proof, modular, quick-charging capability, fulfils DIN EN 1175, 24 V to 120 V, 140 Ah to 700 Ah.
longevity ensured by Q-Leveling

Last but not least, ecological criteria have now come to be included in decision-making criteria: the CO2 footprint, sustainable recycling or a second-life option. It goes without saying that the type of plant duty, together with the associated range of investment cycles, must give rise to diversity in the weighting of objectives, although the same basic requirements still apply. The process of defining the requirements essential to the achievement of the operator’s plans will call for a differentiated study of the employed lithium ion battery, the energy system (charger/battery combination) and the company’s assessment of the system supplier/manufacturer.

ROI and profitability

Let’s start with profitability. This has a direct correlation with service life in the case of the lithium ion battery, or you could refer more specifically to a correlation with the number of operating cycles.
In the field of in-house logistics, we refer to “end of life” only after the nominal battery capacity has gone down to 80%. Once that’s the case, it doesn’t mean the battery is no longer usable.

There are great differences between available charging cycle figures, if we compare some of the currently available lithium battery systems, and this will vary according to the employed BMS (Battery Management System). These differences become all the more pronounced if we compare batteries equipped with a BMS plus conventional balancing against a BMS which already uses the new Q-leveling process.

Longer service life

The service life of this latest generation of lithium power systems, enhanced with Q-leveling, is significantly longer. It basically means that you get a longer overall life-cycle and – consequently – a longer useful daily service time.

Accordingly, in a plant which works on a multi-shift basis, considerable time can be saved since less time needs to be spent on interim battery charging.

Up to  30% higher efficiency

Let’s look at the energy system, which is the combination of lithium ion battery power and our charging technology.

These need to be ideally matched to each other, and this applies both to hardware and to software. Consequently, any faults which lead to floor conveyor failures will have a direct repercussion on the profitability of the whole production process.

Modular-design chargers offer the advantage – in this context – that they can still be operated at reduced power even if one module fails. Accordingly, the floor conveyors can still be charged. Furthermore, the modular design enables an extension or a reduction together with straightforward, rapid replacement of the module while work continues in the plant, so that – here, too – the repair/shutdown times are greatly reduced.

Operating costs represent a major proportion of the overall costs.



As the number of cycles increases, each cell will suffer an individual capacity loss determined by ageing. This individual process is further accentuated within a battery system. This gives rise to differences in capacity between cells, increasing over a period of time and greatly reducing any battery system’s anticipated service life. Q-levelling takes a completely innovative approach to slowing down this system-induced ageing process suffered by lithium batteries. This is a patented process which can be licensed and used by all battery manufacturers.

With Q-Leveling, the system’s assessment doesn’t rely exclusively on knowledge of the cells’ voltage curves.
Q-Leveling’s innovative measurement & control algorithms continuously collect the details of each individual cell’s SoC (state of charge) and SoH (state of health) so as to detect individual charge levels and ageing-induced changes in capacity. Because charging currents are managed precisely throughout the charge/discharge phases, you can avoid (or largely compensate) differences in charging levels between cells. This is achieved by way of an additional secondary power circuit which can dynamically treat each cell with an individual charge/discharge current.

Advantages of Q-leveling:

  • The working capacity of the battery as a whole is no longer affected by the weakest cell in a series circuit. This means that more usable energy is available throughout a battery’s entire life-cycle.
  • The ageing mechanisms suffered by a battery due to series connection will be compensated or even virtually avoided altogether.
  • The battery system service life we can anticipate subject to having Q-leveling is almost comparable to an individual cell’s life expectancy.
Here is a comparison of the charge/discharge processes of a lithium ion battery with a conventional BMS or with a BMS comprising Q-leveling
Here is a comparison of the charge/discharge processes of a lithium ion battery equipped with a conventional BMS or with a BMS comprising Q-leveling.
Comparision of the service life of a lithium ion battery (LFP 8S1P) equipped with a BMS or with a BMS plus Q-leveling
Here, we’ve compared the service life of a lithium ion battery (LFP 8S1P) equipped with a BMS or with a BMS plus Q-leveling. Our comparison illustrates the repercussion – on the whole system – of one cell’s loss of power. The loss is markedly reduced if the Q-leveling process is employed.

Because the costs of energy are significantly represented, here, our systems’ energy efficiency must be an important criterion. For example, the efficiency achieved with BENNING’s BELATRON chargers comes to approximately 96 %.

By now, nobody questions whether conventional lead-based technology or modern lithium ion tech will give the greater energy efficiency.

Schließlich erfolgt die elektrochemische Umwandlung der elektrischen Energie in der Bleibatterie mit einem Wirkungsgrad von nur ca. 70 %. Die höheren Verluste sind im chemischen Prozess der Bleibatterie begründet.

In the final analysis, the electrochemical conversion of the electrical power in a lead battery offers an efficiency level of no more than approximately 70%. The relatively higher losses are due to the chemical process in the lead battery.

The use of a lithium ion power system does more than to just save up to 34% of the energy costs entailed in operating a floor conveyor. More than that: the CO2 emissions when charging lithium ion drive batteries are reduced by the same factor.

Even after no more than around two years, the additional costs for investing in a lithium iron energy system are covered by the saving in operating costs. This is illustrated on the basis of comparing the 24 V, 7.2 kWh (280 Ah) liflex NG energy system with a 24 V – 375 Ah lead battery. Approximately 34% reduction in power draw, approximately 75% less spent on servicing and approximately 60% less spent on battery maintenance – a massive contribution to a successful investment.

Increase your plant’s loading capacity

Interruptions to the floor conveyor’s operation will cause reduced efficiency. Consequently it pays to keep charging periods as short as possible, or to program them completely outside of normal operating periods. For example, if you can carry out interim charges in the respective breaks (1×15 minutes and 1×30 minutes) in the context of 2-shift working, then you don’t need a replacement battery.

For that purpose, though, not only the chargers but also the lithium ion storage systems must be designed for rapid charging at high current levels.

Liflex NG energy systems fulfil this requirement: they have quick-charging capability and can therefore be used effectively for interim charging. Charging takes place at a constant current level.

Versatility when it comes to investing or replacing equipment later on

Remember: sustained soundness of investment presupposes the maximum possible compatibility. What this means with regard to chargers is that, amongst other considerations, you need to be able to charge conventional lead batteries in the first place and then – after transitioning – to charge the up-to-date generations of lithium ion batteries.
The ideal option is for systems to be correspondingly converted using firmware updates.

Graph and comparison of usable energy for lead and lithium batteries + 34% higher energy costs for lead batteries
Comparison of usable energy in lead and lithium batteries
The extra costs from investing in a liflex NG energy system are compensated by the savings on operating costs – even after just two years
The extra costs from investing in a liflex NG energy system are compensated by the savings on operating costs – even after just two years
Annual energy consumption and CO<sub>2</sub> emissions from charging of drive batteries: lead battery (Pb) / lithium ion battery (Li)
Annual energy consumption and CO2 emissions from charging of drive batteries: lead battery (Pb) / lithium ion battery (Li)
Diagram of the capacity curve of a liflex NG energy system in 2-shift operation with opportunity charging
Capacity curve of a liflex NG energy system in 2-shift operation with opportunity charging

When selecting a lithium battery system manufacturer, take note of the extent to which the manufacturer continuously redevelops not only hardware but also software. This is going to require a high level of priority, particularly if a fleet of vehicles is to be managed and/or if one’s energy systems are connected with an in-house EMS (energy management system).

All-round flexibility

Let’s assume that a company wants to start with a trial basis: equipping a few of the floor conveyors about to be purchased (or already in place) with lithium ion batteries.

The maximum of flexibility – systems can be operated in the upright position or horizontal
The maximum of flexibility – systems can be operated in the upright position or horizontal

The existing vehicle fleet will be upgraded step-by-step over a period of time.

From the operator’s viewpoint, it would then make financial sense for all of the employed energy systems to be covered by a single source for repairs, servicing and rentals.

However, this can be tricky, given the diversity of various vehicle types. In many cases, after all, the available battery systems can only be obtained in a small number of standard sizes.

Ideally, a given battery manufacturer should offer flexibility, so that the lithium ion batteries – and also the battery trays – can be configured individually for the various vehicle types.

With that in mind, in our latest liflex NG battery generation, we’ve developed a modular concept.
This series can be obtained in two types of module: standard and slim. Both module types have the same capacity. A different arrangement of cells is employed for the various casing sizes.

Systems/modules can be operated either in the upright position or horizontal. This achieves greater flexibility, depending on the installation location.

In parallel, specifically sized battery trays are available.

Example of several liflex NG module configurations (standard or slim / lying or standing) next to each other in a diagram
Examples of liflex NG module configurations (standard or slim / lying or standing)

Servicing and preventive maintenance will guarantee a long service life

Present generations of lithium energy systems are largely maintenance-free. At the same time, each system should be serviced at regular intervals in order to ensure a long service life.

This can be achieved by the operator’s trained personnel or by the manufacturer’s service engineers.

BENNING offers an extended guarantee under its service contract for preventive servicing and life extension.

Sustainability: thinking and acting

Ecological thinking means considering more than just the energy efficiency of our systems. Responsible action also means looking into what happens to lithium ion batteries after their EOL.

Ideally, batteries can be sent back to the manufacturer for recycling and/or second-life concepts.

Conclusion:

It may ultimately be concluded that the service life of lithium ion energy systems actually represents a considerable proportion of an investment’s cost effectiveness.

Here, there are significant differences between the service life achieved by currently available lithium ion energy systems. To some extent, they are achieved by various manufacturers’ embracing BMS: with conventional approaches to balancing.

Recently developed approaches are available (Q-leveling), and these can enhance a system by 30 to 40% until EOL.
A checklist of requirements for any lithium system should consider the following points: Service life, energy efficiency, rapid-charge and interim charge capability, modularity, compatibility and the connection options offered by systems.

Additional protection can be gained if we use a checklist of requirements awarding appropriately high priority to these criteria, followed by the requirement for a long guarantee period together with a service contract; and these considerations on their own are already an indication for the quality of any battery system.

Straightforward rental/tryout

Rental models for industrial assets – totally matched to a company’s particular operating procedures – are now a fixed component of any company’s financial planning. They provide the operator with some certainty in their planning, they enable the use of the most modern products and they offer versatility and the maximum availability, all for a fixed monthly price.

BENNING’s rental model for energy packages is designed not only for vehicle and battery dealers but also for companies which operate floor conveyors. It gives you the opportunity to satisfy yourself as to the advantages of lithium ion tech in practical operation but without incurring any risk.

It means that there are no high initial investment costs or unpredictable expenditures on servicing, maintenance or replacements. Rental instalments remain stable. The outcome is a fleet of floor conveyors which remains available at all times. Upon expiry of the contract term, the complete energy package can be acquired.

The rental model offers comprehensive, complete service for your entire energy package

All of the above should be included in the list of requirements upheld by responsible companies, together with an ecologically sustainable recycling or second-life solution – offered by the battery manufacturers – for each lithium ion battery system.

Further information

author/contact: Peter Höptner
telephone.: +49 2871 93 233
e-Mail:

Peter Höptner,
Traction Distribution Manager,
BENNING

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