The future of DPF servicing

Change can seem shocking at first, but is it the future?

By Frank Massey | Published:  08 May, 2017

Two months from now will bring my tenure in the motor industry to 49 years. I would like to think I have evolved, kept up with technology, enabling me to provide a professional service, enjoying customer respect and integrity. My focus has been the technical challenges, while my son David manages the commercial responsibilities.

This creates a wide role for me developing our training programme, internal research and development, bringing the focus of this topic to technical and legal compliance.

My chosen subject here is diesel servicing and repairs, specifically particulate filtration and emission control. It is something we have been passionate and vocal over for several years. it gives me no pleasure or satisfaction in seeing our prediction over the demise of diesel vehicles.

Diesel fudge

The future is now clear as to the changes our political lords and masters have in mind. This gives us a short timeline to get our house in order. My intention is to advise, help and warn what will happen if we all continue to fudge diesel particulate repairs as we currently do. Upwards of 90% of independent garages will fall into this category. How do, or should we service and recover diesel particulate filters? The choices are very simple!

1. Replace with a new OE filter

2. Replace with a non-OE filter

3. Clean and service off vehicle in factory controlled conditions

4. Clean and service off the vehicle in house

5. Clean and service on the vehicle

6. Remove the filtration system from the vehicle

Here is the problem; we as professional repairers are legally and financially responsible, and exposed for the advice and decisions we make. This is the case even if the customer agrees and or instructs us on a certain course of action.

Clear legislation is in place for the performance and fitment of diesel emission systems. Vehicle taxation is based on specific emission levels agreed with the manufacturers. I am sure I do not need to mention VW and Audi, but I will bet their corporate accountants have regrets. How long do you think it will be before the government bean counters look at us? Let's not fool ourselves enforcement will take the effect of stringent fines.


So what are we doing wrong? Pretty much everything. Please remember my words, help, advice and not critique.

We are breaking the law in removing legally compliant systems. MOT examiners will lose their licence by passing unauthorised emission system modification. You will become the first unpaid enforcers.

We are breaking the law further in polluting the water course, by power cleaning, or rinsing out cleaning agents into the drains. Utility companies have powers to set huge fines and often do.

We are also in breach of the clean air act by using some of the available cleaning agents that require the running of the engine whilst emitting all the contaminants back into the environment.

It is quite possible at this point some of you are about to rip out the magazine pages and offer an alternative use for them. Please reconsider, we are slowly killing ourselves.

Let's as an industry get together, think ahead of the curve and get our house and process in order.


I recently visited CERAMEX in Slough, and before a handful out there suspect a paid endorsement here, I even paid my own travel expenses. I have been aware of several companies offering off vehicle cleaning, pressure washing, thermal cleaning in an oven, and ultrasonic treatments. My problem has always been, is the catalytic converter and DPF still fully functional and durable when refitted? How can we protect ourselves from future premature failure due to other indirect causes? Can we provide certification of test results?

Here is my opinion as to how we should address the blocked, cleaning DPF problem. Many of you will not agree, I do not care, this is how it should and eventually will be done. Reflect on the vast changes in the paint refinishing industry before you cry never!

The DPF is initially visually examined bar coded and weighed, attached by means of bespoke plumbing to what is in effect a big dishwasher (sorry Marcus my words) then filled with water. A short pause here, some of you will know water damages and degrades the precious metal wash coat. The purified water has all the damaging trace elements removed and is only used to restrict the clear DPF passages. Pressure waves, are then sent through the core, XPURGE for several minutes. I did question if this was in effect an ultrasonic process? This is not the case. The water does act as a transport mechanism for the waste material, including ash, which is flushed out, into a waste tank. The water is filtered, for reuse and the semi solids captured in large skips for reprocessing. It is pure carbon it would make an ideal fuel source!

The DPF core is then placed in electric air dryers where apart from drying the core, measurements are taken for flow rates and back pressure. Next a two-stage photograph examination is applied to detect face off and ring off cracking to the core. A second weight check is taken to ascertain the mass of soot ash removal. The next service is optional for small vehicle units, the cat and DPF are subject to a sample hot gas bench to establish the reduction of, CO/HC, finally being placed in a particulate bench where filtration is assessed and measured.


Certification and bespoke transport packaging completes the service. The recovery success is consistently above 90%. The cost is approximately half the cost of a new OE unit. No environmental pollution so your grandchildren will thank you and may avoid the huge increase in paediatric respiratory illnesses.

You will earn profit from a professional repair, enjoy the respect and integrity it brings, however not all customers will agree or want to pay, and that is not our problem.

Further information

Please contact Annette 01772 201 597, for further information on upcoming training courses and events.

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  • Ignite your interest in ignition  

    This month’s subject was prompted by a recent conversation with a colleague in Australia. The conversation included an invitation to a technical festival in October, where it was said that ignition would be one of the subjects of interest. Many years ago, when I began developing our training programme, ignition was a subject of primary concern when diagnosing gasoline
    engine problems.

    This is a complex subject often not fully understood and often overlooked. Its vital importance recently became apparent in our workshop, when we were presented with two Audi rs6 engine failures. One failure has yet to be investigated the other suffered piston failure due to combustion faults.

    The increasing complexity of homogenous and stratified fuelling, split injection delivery and variable valve timing geometry has placed critical responsibility on ignition performance. Often within the diagnostic process there is no serial evidence of an ignition problem, or that what evidence is available is incomplete especially at the early stages of failure. The process has not changed in over 30 years;  You must scope it.

    Process overview
    So here is an overview of the process. Firstly, you must understand that it requires a specific amount of energy to completely combust the air fuel charge. Ignition energy is measured in joules, our task it to ensure the energy is created and delivered correctly. The primary circuit bears the responsibility of energy creation with current profile as the focus of our measurement. The secondary circuit has the responsibility of delivery, our focus is burn time and slope profile.

    I accept that both circuits have a shared responsibility at the point of induction where energy within the primary is transferred into the secondary. The physical challenge is the method of accessibility. With static or direct ignition it is often not possible to connect to the coil primary circuit, leaving the option of induction as the method of measurement. The primary will always have a power and switched ground, so current measurement using a suitable hall clamp is always possible.

    Diagnostic observations
    The four critical diagnostic observations in order of priority are:
    Ignition burn time measured in milli-seconds with a range of 1-3ms depending on ignition type. Do not assume length of burn relates to energy value Primary current profile with a range of 3amps (points ignition) 20amps static ignition. Note the expression profile, it includes rise time and rate of collapse Coil ringing, this is the resonance at the end of the burn event it represents the small residual ignition energy returned in to the coil secondary winding Firing line voltage, this represents the value of electrical pressure in delivering the induced energy to the spark plug electrode it includes all components in the delivery process

    You must also understand that the performance of the injector, cylinder turbulence, and mechanical efficiency forms part of the combustion process. Intake air temperature, pumping losses and fuel quality all affect the burn process. Let’s begin with the tool I distrust the most! Serial data is a good first look – there is some very useful information such as cylinder misfire count, ignition timing individual timing retard data, air intake temperature and exhaust temperatures. There may also be additional data on burn time and primary charge time, but I don’t trust or rely on it.

    So, out with my Pico scope. Connectivity can be a challenge, over the years we have built our own probes, however, if the manufacturers can run a circuit there you can scope it. There is a simple logic process.  Begin with burn time, look at the duration and slope it – It should be roughly parallel with the horizon.

    A rising line confirms a difficult transition of energy across the electrode. Lean combustion, glazed plug, cylinder pressure, plug performance. Cylinder turbulence.

    A falling slope represents the opposite condition; low cylinder pressure, fouled or shunting plug circuit, small plug gap. The burn profile should be relatively smooth, a turbulent burn path confirms difficult in cylinder conditions. It can and does point to injector fuel delivery problems especially if a sharp rise at the end of the burn time is present.

    You may appreciate now just how vital scope evaluation is.

    Primary current path confirms good power supply and the performance of the power transistor in its ability to switch and hold load to ground. Note the rise time characteristics and the off switch, under shoot here is a good indication. If you can, observe primary voltage. Note the slow rate on load, it’s the slow rise in voltage during coil charge time, a problem here will affect current flow so go for current first its easier to understand. Remember one of my core diagnostic rules; If it moves, gets hot, or applies a load measure current!

    Coil ringing is the inverted energy returned into the coil secondary. With no path to ground,  it gradually gets weaker, converting its energy to heat. Expect 2/3 rings in current systems. If the coil windings are compromised in any way a reduction in inductance will follow. The rings will disappear, ignition energy may still be present but a reduction in value will result. Be warned this condition will never be known if not scoped and critical engine failure often follows.

    Firing line voltage can only be measured accurately in primary to be honest. Expect the following values:; Conventional rotating ignition 50v, wasted spark ignition 40v, direct ignition30v; Plus or minus 5 v on all values. The problem with exploring this with a coil probe is that the probe attenuation is not known, so its difficult to scale.

    I hope this helps. It is a very complex subject , often neglected and overlooked.

    Just before I go here is a challenge; How many information systems, VMs especially, don’t give these four  vital statistics? So how do they know if there is a problem?

  • All the things YOU could do…  

    If you had a little money, how would you spend it to improve your business? Maybe you’d buy the latest ADAS calibration kit, or subscribe to an workshop management system?

    Okay, now let’s think bigger. If you were given all the money you had ever invested in your business and could start it again from scratch, how would you gear it up to attract customers and make it profitable? Would you build something like
    your current business, or would it be totally different?

    Why do I ask? Because the world changes quickly, which means our businesses are rarely set up exactly as we need or want, and we must make frequent spending decisions. We must work out how to prioritise our spending, to ensure we always offer the things of greatest worth to our customers; i.e. we maximise our value proposition.

    Last month, we sought to understand our typical customer (a private vehicle owner). We saw that they have functional, emotional and social tasks to complete (jobs). These jobs have either good results (gains), or bad outcomes, risks and obstacles, related to their undertaking or failure (pains). For example, taking a car to the workshop is an extreme pain for a typical customer because it makes it more difficult for them to complete their more important jobs (e.g. commute to work or navigate the school run).

    This month, we’ll use the things we learned about our customers to design our value proposition; We’ll use a repeatable technique to ensure our businesses offer the things our customers need and want. The result will be a value (proposition) map, or value map for short.

    Value mapping
    Anything that helps our customers get their jobs done will have value. Therefore, our products and services must aim to help them complete their jobs. If these products and services then eliminate a customer’s pains, they are pain relievers, or, if they produce gains, they become gain creators. By stating the ways in which our products and services create gains and relieve pains, we can communicate their potential benefit to our customers. Hence, by putting a list of our products and services together with the lists of their respective pain relievers and gain creators, we create a guide to the worth of our business to our customers. That is, we make a value map.

    Of course, not all our products and services, and their subsequent pain relievers and gain creators, are equally relevant to our customers; some are essential, whilst others are merely nice to have. We can use these differences to help our decision making: by ranking the items in our value map in their order of relevance to our customer, we can see which can be ignored, and which can be prioritised.

    Figure 1 shows example items that might be within an independent workshop’s value map, ranked in order of relevance to a private-vehicle-owning customer (a value map is targeted at a specific customer segment). As with the creation of a customer profile, there is no ‘right’ answer; this one is based on my half-thought-through assumptions, and previous business experiences. Yours might differ. Hence, we must derive and tweak our respective value maps accordingly. Ultimately, each of us would use business metrics (e.g. profit ratios and customer satisfaction ratings) to tune our value propositions to the max. But that’s a task for another time.

    Products and services
    We saw before that customers don’t like to waste time at a workshop; they want to go through their lives with the minimum of hassle. They crave convenience. Therefore, courtesy cars, a handy location (covered under ‘community-orientated’ services in Figure 1), extended opening-hours, while-you-wait servicing, or pick-up and returns (either vehicle or customer) all represent high value offerings. We don’t have to offer them all - they’re included in Figure 1 for reference. Likewise, online bookings and related management systems simplify engagement, bring convenience, and enhance value.

    Have you ever heard a customer say they like messy and dirty workshops and technicians? I haven’t. That’s because we attach value to our health and safety: If your premises and staff are well presented, they will project professionalism, and your customers will reach their desired emotional state of feeling safe. Even better, properly motivated, well-equipped and trained staff will increase the likelihood that your customers are safe and secure. As safety fears are powerful motivators and manipulators, we must use our expertise to help our customers assess and manage their exposure to risks. They will then be in control and feel in control of their safety.

    Not all customers will be seeking to cut costs all the time, but certainly all of them will want to control their costs. There are ways a business can help customers manage this aspect of their lives: clear terms of trade and fee structures; well-managed engagements with expert advice; warranted parts and labour; and a range of payment methods such as easy-pay solutions, touch-less, or credit card services.

    Surprisingly, some customers want to look after their vehicles. Primarily, this helps them feel safe and secure, minimises the risk of disruption to their lives (from breakdowns), and protects the value of their vehicles. A good service history represents monetary value in this sense. This means we should be offering, high quality parts and labour, and OE-aligned servicing and repairs.

    Pain relievers
    It might suit your ego to think all your customers visit your workshop because of your skill, expertise and professionalism, or your friendly welcome and great (i.e. free) coffee. However, pure convenience can be the decisive factor when some customers choose where to take their vehicles: you’re around the corner; you had a spare courtesy car; you’re open; you were prepared to look at it there and then; you had the part in stock etc. Whilst this reflects the significant value these pain relievers offer to all our customers, it is the case that some of those who value convenience above all else are not able to see the worth of your other products and services. If they don’t understand that your conveniences come at a cost, then point them elsewhere. You will never please them. Nothing has the potential to sour a relationship like an unexpected bill: When my head was buried in an absorbing diagnostic job, adequate communication was sometimes an issue for me. My ‘solution’ was to swallow the costs, to avoid upsetting the customer. This was neither a solution nor a sustainable business strategy. What I really needed was the best preventative medicine of all: Great communication.

    It should be no surprise that there are far more pains than gains in our value map: Servicing and repair workshops are all about pain relief; we are either trying to eliminate a current pain, through diagnostics and repairs, or carrying out preventative maintenance to avoid a future pain. Because this is our reason for being, customers find it intolerable to think our actions have caused them unnecessary inconvenience or costs. Nowhere is this more obvious than when we try to ‘help them out’ -  Every time we ever tried to help a customer to control costs (i.e cut costs), by fitting a cheaper part or trying a less expensive solution, it always backfired. Every single time. Can you guess who suffered the consequences? It always paid us better to ensure the car was fixed when it left the workshop. ‘Try it and see’ tends to translate into ‘you are going to be really cheesed off next time I see you’, It also counted that we supplied quality, parts and labour.

    Gain creators
    When properly delivered, our products and services will help our customers have the following: An easy-life; a car that holds its value and works properly; peace of mind; a sense of feeling special at our premises; and the information from our sound advice to make good decisions.

    However, for some of us, the ultimate convenience is to not have to engage our brain, so if we really want to take our value proposition to the next level, we must be highly proactive and perform our customers’ thinking for them: e.g. by sending MOT and service reminders, with easy to process ‘calls to action’ so that they are only a click away from being sorted. Then, at the allocated time, we would pick-up their vehicles from their homes to take them to the workshop, leaving a replacement vehicle in their place. I know plenty of businesses that do this. And they are successful.

    Money, money, money
    There are many servicing and repair options available to private vehicles owners: Independent workshops, fast-fit chains, main-dealer workshops, mobile technicians, chancers, etc. Next time we’ll see how other business types deliberately tweak their offerings (value maps) to fit specific customer segments. We need to learn to be equally deliberate and well-informed about our investment decisions. What if we don’t? Well, we might waste all our money, and lose all our customers. Which isn’t always funny, even in a rich man’s world.

  • How to create diagnostic superheroes 

    Have you ever had that sinking feeling? You know the one. It’s 08:30 on Monday morning and your best technician is walking towards you with a forlorn look and an envelope in his hand.

  • The good and the great 

    Being part of Top Technician for the last few years, I have seen many technicians succeed and develop new skills. Typically all are good rounded technicians and have great knowledge, but what makes the difference and makes the good into the great?
    It’s not just that they are lucky. The difference is that a great diagnostic technician will have a well-defined diagnostic process (or procedure) that they stick to every time.

    Some technicians start their diagnostic procedure with a well laid-out and defined process that they have normally learnt, often from training courses. As with any new process, it starts slowly as theory is put into practice until it becomes natural.
    Many technicians typically revert ‘back to type’ during the early stages, as their older method seems to make the diagnostic process shorter. As a result they believe it could make them more money. Yes, in the short term they may be right. However, normally in the longer term a well-defined diagnostic process proves to be infallible especially when the fault is difficult to diagnose or a vehicle that has been to several garages and the fault is still apparent.
    Many technicians also try to shortcut the process, taking out some of the steps that don’t seem to help in finding the answer. Sometimes a simple fault is made more complex by the technician overlooking the obvious in the second or third step, jumping from step one to step four because that’s where they feel comfortable. In this series of articles I’ll be covering the 10 steps that make up a well-planned, well organised, tried and tested diagnostic process. Use the process and refine it within your business, it works.
    Many businesses use a similar structured process and base their estimating/costing model on it
    as well.

    Let’s start at the beginning, with the meaning of diagnosis. Most technicians will look at the word and think it only relates to a computer controlled system and they have to use a fault code/scan tool to be able to diagnose a fault. This is not the case. Diagnosis can relate to any fault, whether that is electrical or mechanical. Therefore, the diagnosis can relate to an electronic fault by the malfunction indicator lamp (MIL) indicating a fault exists or a mechanical fault that exists within a clutch operating system.
    The meaning of diagnosis is: ‘The identification of a fault by the examination of symptoms and signs and by other investigations to enable a conclusion to be reached.’
    Or alternatively: ‘Through the analysis of facts of the fault, to gain an understanding which leads to
    a conclusion.’
    Both can relate to various professions.
    With this in mind, what have celebrity chef Paul Hollywood, your doctor, the green keeper at the local golf course and a automotive technician all  got in common?
    They all use a diagnostic process within their profession. Paul Hollywood is often seen as a judge within baking competitions. He uses his experience and process to perform a diagnosis on why a bread is not cooked correctly.
    Meanwhile, a doctor uses a diagnostic process to find an illness. A green keeper uses a diagnostic process to determine why the grass does not grow as green as it should, while a automotive technician performs a diagnostic process to find the fault on a vehicle.

    Let’s begin to go through the steps of the diagnostic process.

    Step 1: Customer questioning

    Being able to question the driver of the vehicle of the fault is always a very important part of the diagnostic process. Using a well-structured and documented series of questions can determine how the fault should be approached. Many experienced technicians do this part very well, but when a business becomes bigger, the customer’s information on a fault can get lost  when passed between the receptionist and the workshop.
    A document can be developed to perform this task, and is often the solution here.
    A customer has often seen a ‘warning lamp’ on the dash. They can only remember that it was an amber colour and it looked like a steering wheel. The document shown has a variety of warning light symbols that they can simply highlight to let the technician know of the MIL symbol and in the circumstances that the fault occurs (driving uphill around a right-hand bend etc).
    Much of the diagnostic process is about building a picture before the vehicle is worked on. Trying to fix the fault by jumping to step 4 or step 5 can often neglect what the customer has to say. One of the last steps in the diagnostic process is to confirm that the fault has been correctly repaired and will not occur again (‘first time fix’). How can the fix be successfully tested if the circumstances where  the fault occurred are not replicated during the final stages of the process?
    The MIL illuminating again (recurring fault) when the vehicle is driven by the customer is not always as easy to fix a second time, as you need to fix the vehicle fault as well as fix the customer, who has been forced to return.

    Step 2: Confirm the fault
    Some technicians just seem to take the fault highlighted as by the job card (or similar document) and diagnose the fault without first confirming, which can take some time to complete. This step might involve a road test to confirm that the fault exists. The apparent fault may be just a characteristic of the vehicle or the receptionist/customer may have explained the fault to be on the other side of the vehicle.
    Therefore, it is imperative that the technician confirms that the fault exists and the situation that the
    fault exists within, all providing additional information on building
    the picture before actually working
    on the vehicle.

    Step 3: Know the system and its function
    In order to fix a vehicle fault(s) a technician will first need to understand how the system works. If a technician doesn’t know how the system works how can they fix it?
    Don’t be shy or foolish and indicate that a technician knows everything (even on a specific manufacturer brand). Every technician sometimes needs to either carry out new system training or just have a reminder on how a system works.  
    With all the systems now fitted to a vehicle, it’s not surprising that a technician cannot remember every system and its function especially to a specific vehicle manufacturer or the model within the range. A technician may just need to remind themselves on the system operation or fully research the vehicle system.
    Most vehicle manufacturers will provide information on how a particular system works and how that system integrates (if applicable) with other systems of the vehicle. Spending some time researching the system can pay dividends in terms of time spent diagnosing the system and it is also educational. System functionality can often be learnt from attending training courses but if these are not available the information can be sourced from various other sources such as websites.
    External training courses can provide additional benefits especially discovering how a system operates and understanding its functionality and how the various components work. They will also allow the technician to focus on the specific system without the distraction of customers or colleagues.
    Once the system is thoroughly understood, the technician may be able to make some judgements as which components are ok and those which may be faulty and affect the system operation.

    Just to recap on the three diagnosis steps covered in this article, these were:
    Step 1: Customer questioning
    Step 2: Confirm the fault
    Step 3: Know the system and its function

    Remember to follow the process and don’t try to short circuit it. Some steps my take longer to accomplish than others and some may be outside of your control (it may be necessary to educate others). Practice, practice, practice. Refine the process to fit in with your business and its practices, align your estimating/cost model to the process to be able to charge effectively.

    Next steps
    In the next article I will be looking at the next four steps which are seen to be:
    Step 4: Gather evidence    
    Step 5: Analyse the evidence
    Step 6: Plan the test routine
    Step 7: System testing

    The last article in this series will indicate the final three steps and how to fit them all together in order to become a great technician and perhaps win Top Technician or Top Garage in 2018. Go to to enter this year’s competition. The first round is open until the end of February 2018.
    Every entry is anonymous so have a go!

  • technologies of electric and hybrid vehicles  

    In the previous two issues, we looked at the way batteries store energy. We could in fact compare a battery to a conventional fuel tank because the battery and the tank both store energy; but one big difference between a fuel tank and a battery is the process of storing the energy. Petrol and diesel fuel are pumped into the tank in liquid/chemical form and then stored in the same form. Meanwhile, a battery is charged using electrical energy that then has to be converted (within the battery) into a chemical form so that the energy can be stored.

    One of the big problems for many potential owners of pure electric vehicles is the relatively slow process of
    re-charging the batteries compared to the short time that it takes to re-fill a petrol or diesel fuel tank. If the battery is getting low on energy, the driver then has to find somewhere to re-charge the batteries, and this leads to what is now being termed ‘range anxiety’ for drivers.

    Whilst some vehicle owners might only travel short distances and then have the facility to re-charge batteries at home, not all drivers have convenient driveways and charging facilities. Therefore, batteries will have to be re-charged at remote charging points such as at fuel stations or motorway services; and this is especially true on longer journeys. The obvious solution is a hybrid vehicle where a petrol or diesel engine drives a generator to charge the batteries and power the electric motor, and for most hybrids the engine can also directly propel the vehicle. However, much of the driving will then still rely on using the internal combustion engine that uses fossil fuels and produces unwanted emissions. The pure electric vehicle therefore remains one long term solution for significantly reducing the use of fossil fuels and unwanted emission, but this then requires achieving more acceptable battery re-charging times.

    Charging process and fast charging
    Compared with just a few years ago, charging times have reduced considerably, but there are still some situations where fully re-charging a completely discharged electric vehicle battery pack can in take as long as 20 hours.  It is still not uncommon for re-charging using home based chargers or some remote chargers to take up to 10 hours or more.

    Although there are a few problems that slow down charging times, one critical problem is the heat that is created during charging, which is a problem more associated with the lithium type batteries used in nearly all modern pure electric vehicles (as well as in laptops, mobile phones and some modern aircraft). If too much electricity (too much current) is fed into the batteries too quickly during charging, it can cause the battery cells to overheat and even start fires. Although cooling systems (often liquid cooling systems) are used to help prevent overheating, it is essential to carefully control the charging current (or charging rate) using sophisticated charging control systems that form part of the vehicle’s ‘power electronics systems.’

    Importantly, the overheating problem does in fact become more critical as battery gets closer to being fully charged, so it is in fact possible to provide a relatively high current-fast charge in the earlier stages of charging; but this fast charging must then be slowed down quite considerably when the battery charge reaches around 70% or 80% of full charge. You will therefore see charging times quoted by vehicle manufacturers that typically indicate the time to charge to 80% rather than the time to fully charge. In fact, with careful charging control, many modern battery packs can achieve an 80% charge within 30 minutes or less; but to charge the remaining 20% can then take another 30 minutes or even longer.   

    Battery modules
    Many EV battery packs are constructed using a number of individual batteries that are referred to as battery modules because they actually contain their own individual electronic control systems. Each battery module can then typically contain in the region of four to 12 individual cells.  One example is the first generation Nissan Leaf battery pack that contained 48 battery modules that each contained four cells, thus totalling 192 cells; although at the other extreme, the Tesla Model S used a different arrangement where more the 7,000 individual small cells (roughly the size of AA batteries) where used to form a complete battery pack.

    The charging control systems can use what is effectively a master controller to provide overall charging control. In many cases  the electronics contained in each battery module then provides additional localised control. The localised control systems can make use of temperature sensors that monitor the temperature of the cells contained in each battery module. This then allows the localised controller to restrict the charging rate to the individual cells to prevent overheating. Additionally, the localised controller can also regulate the charging so that the voltages of all the cells in a battery module are the same or balanced.

    One other problem that affect battery charging times is the fact that a battery supplies and has to be charged with direct current (DC) whereas most charging stations (such as home based chargers and many of the remote charging stations) provide an alternating current (AC). Therefore the vehicle’s power electronics system contains a AC to DC converter that handles all of the charging current. However, passing high currents through the AC to DC converter also creates a lot of heat, and therefore liquid cooling systems are again used to reduce temperatures of the power electronics. Even with efficient cooling systems, rapid charging using very high charging currents would require more costly AC to DC converters; therefore, the on-board AC to DC converter can in fact be the limiting factor in how quickly a battery pack can be re-charged. Some models of electric vehicle are actually offered with options of charging control systems: a standard charging control system which provides relatively slow charging or an alternative higher cost system that can handle higher currents and provide more rapid charging.

    Home & Away
    One factor to consider with home based chargers is that a low cost charger could connect directly to the household 13-amp circuit, which would provide relatively slow charging of maybe 10 hours for a battery pack. However, higher power chargers are also available that connect to the 30-amp household circuits (in the same way as some cookers and some other appliances); and assuming that the vehicle’s AC to DC converter will allow higher currents, then the charging time could be reduced to maybe 4 hours operate (but note that all the quoted times will vary with different chargers and different vehicles).

    Finally, there are high powered chargers (often referred to as super-chargers) that are usually located at motorway services or other locations. These super-chargers all provide much higher charging currents to provide fast-charging (as long as the vehicle electronics and battery pack accept the high currents); but in a lot of cases, these super-chargers contain their own AC to DC converter, which allows direct current to be supplied to the vehicle charging port. In effect, the vehicle’s on-board AC to DC charger is by-passed during charging thus eliminating the overheating problem and the high current DC is then fed directly to the battery via the charging control system.

    In reality, the potential for re-charging a battery pack to 80% of its full charge in 30 minutes or less usually relies on using one of the super-chargers, but battery technology and charging systems are improving constantly, so we
    will without doubt see improving charges times for
    newer vehicles.  

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