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Crisis Management: Updating your battery knowledge

By autotech-nath on September 30, 2020

While a ‘dead’ battery may be a disaster to some car owners, technicians risk courting huge problems if they downgrade replacement technologies. As lockdown harmed many 12-volt batteries, Rob Marshall argues that now is the time to update your battery awareness, before it’s too late.

COVID-19 has and continues to touch our lives. As revealed in the AT special supplement during the summer, batteries are probably the most affected motorcar component of the enforced lockdown. Even if you have not replaced many batteries yet, most degradation that might have developed over lockdown will become apparent as the nights draw in and temperatures drop.

Banner told us that, while it experienced a surge in demand during the spring and summer months, it expects winter sales to be especially buoyant, especially as furlough schemes end and more people start travelling again for work. It reports that its manufacturing plant in Austria took steps during the summer to ensure that production output can meet projected winter demand. GS Yuasa also reassures the aftermarket that it has taken similar measures, after experiencing, what it calls, “a dramatic increase” in battery demand, since lockdown measures were eased.


The reasons why 12v batteries fail, when allowed to discharge gradually, are fairly complex but Yuasa supplies worthwhile reading on this topic: In summary, 12v batteries prefer being fully charged. Should their voltage drop below 12.5 volts, crystals build on the lead-based plate material (sulphation) that becomes either very hard, or impossible, to remove. The rate of severity depends on the rate of discharge and the length of time. The net result is a reduction of capacity.

Unfortunately, many car owners have not received very sound advice about maintaining batteries during lockdown, which has worsened the situation in some cases. It may be worth educating your customer about battery care, should future lockdowns be introduced. GS Yuasa told AT that simply starting the engine once a day will not save the battery; it can possibly accelerate deterioration. This is because the energy lost to start the engine may not be replenished. Therefore, should the vehicle be started once a day and the engine not run for long enough, the battery will become deeply discharged, risking permanent damage.

A further problem is that 12v lead-acid batteries prefer a gradual recharge rate. Yet, many car owners do not appreciate this and imagine that their car’s charging system will replenish the battery fully with the car sitting on their front drives with an idling engine for a quarter of an hour, or less. As sulphation builds, the battery’s internal resistance rises, making the charging system work harder for longer. This situation allows a sulphated battery to ‘trick’ the charging system into thinking that the battery is charged fully, when it is not.

Additionally, virtually all modern cars inflict parasitic drains, on top of the battery’s’ natural tendency to discharge naturally. The rate at which the car does so depends from vehicle- to-vehicle but components responsible range from ECUs, clocks, alarm and immobiliser systems. Faults can also develop that increase this drain, such as courtesy lights that do not extinguish, to alternator defects.

You may find that customers seek your advice on removing and recharging the battery. Providing that the owner is fortunate enough to have a private drive, (or, even better, a garage), then you can recommend that they buy a smart charger and connect the battery permanently to the mains, following the charger maker’s instructions, naturally.

Alternatively, and presuming that their DIY skills are up to the task (or else you can consider offering assistance), they can remove the battery from the car and charge it indoors. While you can advise them to check that the battery’s voltage does not dip below 12.5v and charge it as required, emphasise that any domestic charging must be carried out in a cool and well- ventilated area. As certain batteries can vent hydrogen and oxygen during charging, an enclosed airing cupboard is hardly an ideal location, unless your customer wishes to re-enact the Hindenburg disaster at the flick of a light switch…

When advising about chargers, you might also wish to consider if those in your workshop are suitable for the latest battery technologies. Many decades-old trickle-type chargers languish in DIY garages and professional workshops, which are designed for flooded lead-acid batteries. These apply a constant voltage and a variable current, which declines gradually as the battery reaches full charge. Yet, they do not turn off completely, which risks overcharging, damaging modern sealed batteries, especially. In addition, they do not guard against acid stratification, which is when the electrolyte’s acidity in the battery is stronger at the bottom of each cell and weaker at the top. Smart chargers apply different voltage levels to overcome this, as well as including other programmes to help reverse sulphation. If left plugged into the mains permanently, they possess a maintenance cycle to keep the battery between 95 and 100% charged but they switch off to avoid overcharging. Many smart chargers also have different algorithms to cater for the latest Advanced Glass Mat battery technologies.

Replace battery technologies like-for-like, at the very least. A number of look-up tools will help you to select the battery and guide you through the procedure, which will also give you an idea of how long the task will take.
You might wish to upgrade your workshop charger to a smart charger. Not only is the pictured unit unsuitable for AGM batteries but it also lacks the algorithms
to help break down stubborn sulphation and prevent acid stratification. Always ensure that a charger is compatible with the battery technology. For example, an AGM battery must be charged using an AGM compatible charger type. Failure to do so will result in permanent damage and premature failure.


As with any customer complaint, accurate diagnosis must be your priority. Establish, for example, if a non-start complaint is the fault of the battery, the vehicle’s charging system, or components that draw an excessive parasitic discharge. LKQ Euro Car Parts explained that flat batteries, caused by vehicles’ systems not shutting down correctly, are more obvious when they are not used every day, which explains the increase in flat batteries that occurred soon after lockdown.

Battery testing considers two main parameters: the state of charge is measured in volts but this does not tell you whether, or not, the battery can turn-over a cold engine. The State of Health is established in amps, a figure that is compared with the Cold Crank Amps (CCA) figure printed on the battery side.


While battery technology has evolved, it seems that technician knowledge has not kept-up. This statement was proven last year, when ECOBAT found that fewer than one in ten technicians, of over 400 it questioned, did not know the meanings of SLI, EFB and AGM. Perhaps we should not be surprised. One battery supplier that we contacted did not know, either.

With low emission stop-start and later micro and mild hybrid technologies becoming ever more popular within the past decade, batteries have had to change internally to tolerate the greater number of starts and handle different discharge and charging demands. With very basic stop-star models, the traditional SLI (Starter Light Ignition) is replaced by an EFB (Enhanced Flooded Battery). As its name hints, the EFB remains of the same liquid electrolyte construction as SLI but with numerous changes to enhance charge acceptance. These include thinner but more numerous plates and additional elements used in its construction, such as carbon and lithium.

AGM (Advanced Glass Mat) batteries can also be called VRLA (Valve Regulated Lead Acid) and feature glass mats, which absorb the liquid electrolyte and are pressed tightly against the plates. The result is higher efficiency, a greater tolerance of deeper discharges and a typical 30-40% increase in CCA, compared to EFB and SLI designs. Yet, they are significantly more expensive than flooded types, which poses a hurdle for customers to accept.

Just as brake pads wear whenever the pedal is applied, batteries also wear every time they are used. As stop-start systems increase the number of required engine starts, the different battery technologies need longer lives. GS Yuasa told us that the difference is considerable: A SLI battery tolerates up to 50,000 starts, which jumps to 270,000 for EFB and 360,000 for a typical AGM.


For whatever reason, if you find that the battery has shed much of its capacity, you will need to identify the appropriate battery technology. Resources, such as Banner’s www., ECOBAT’s https://batteryfinder. , GS Yuasa’s and VARTA’s battery-finder and Partner Portal are all useful resources that identifies the OEM specification by vehicle registration number. Many of these sites also show you where the battery is located, how it can be removed and replaced physically and whether, or not, the smart alternator needs to be reset.

This diagnostics intervention is crucial for long life of the new battery. The majority of cars that feature stop-start technology possess a battery monitoring system, which tends to feature a BMS (Battery Management System) sensor on the negative terminal. As the system adjusts its charging algorithms to compensate for battery degradation, until it has reached the end of its useful life, the software must be reset, after you have installed a new replacement. VARTA explains that, aside from potential battery damage through overcharging, various functions could cease to operate, if the diagnostic reset is overlooked. The equipment affected includes not only the stop-start function but also various electrical ancillaries, such as the electric windows and even folding roofs.

Aside from their online portals, battery companies can assist with a comprehensive selection of hardware, too. ECOBAT boasts its ‘ONE BOX’ kit brands/onebox/, comprising a tester, smart charger
and an EOBD-based programming tool. The company is also operating a free battery training, assessment and certification programme. It works by watching this video and taking this assessment Presuming that you pass, you can download a choice of branded (Exide, Lucas, Numax, or VARTA) or non- branded certificates from ECOBAT’s main website: LKQ Euro Car Parts is also emphasising that diagnostic training is important, when tracing parasitic drains and interrogating battery monitoring systems in particular. The company told AT that it is working hard to communicate with its aftermarket customers about the range of battery training options available, through the Auto Education Academy training platform.

Battery deterioration can be hastened by excessive current consumption, after the vehicle’s various ECUs have powered-down. A DC clamp meter is a useful tool to measure current draw. Issues with smart charging systems can be identified with an oscilloscope.
It is a wise idea to test every battery’s state- of-charge (volts) and
state-of-health (amps) on every vehicle that enters your workshop, especially during the autumn and winter months. The readout will either be a percentage, or an amps figure, which is compared against the individual battery’s CCA specification


More exotic materials, increasingly sophisticated battery construction and time-intensive replacement mean that you might face extra challenges from the customer. The days of replacing a battery for under £100 are fading fast and you may have to quote the facts from this article to avoid suspicions (or even blatant accusations) that you are profiteering. Obviously, their higher cost makes it even more important that you do not discard a serviceable battery in the first place through misdiagnosis. Even so, be wary of a number of pitfalls that your customer could suggest to reduce their expenditure.

The main temptation is downgrading the battery technology, so fitting an EFB, or SLI battery, to a vehicle designed for an AGM would be very poor practice. Banner Batteries advise this should be avoided at all costs and joins VARTA and GS Yuasa in stating that batteries should be replaced on a like-for-like basis. Yet, such manufacturers concur that you can upgrade technologies as an upsell. Downgrading, meanwhile, will result in premature battery failure, a main cause of which is damaged plates, through deep discharge and subsequent fast recovery, which flooded lead acid types are not designed to support. Using an SLI in an AGM application can damage it to such an extent that it can lose as much of 16% of its CCA (capacity) in the first week of use. Understandably, this risks the unsatisfied customer returning to you for another battery, and an explanation about why various other functions have ceased working. Battery supplier warranties will not cover damage caused by incorrect applications.

Another problem is some customers supplying, or requesting that you source, a second-hand AGM battery for you to fit. VARTA told AT that is does not recommend this approach, because the used part’s previous life and its condition are unknown. Additionally, the battery management system (BMS) would have configured itself to the old battery and could use an incorrect profile to charge the replacement used one. While it is possible that the BMS might learn the battery’s condition, this is not guaranteed and, even so, would not occur immediately. Regardless, the risks still remain: curtailed battery life, potential dashboard error messages and functions ceasing to work. Obviously, you cannot reset the BMS to any value other than that for a new battery.

Aside from having to overcome customers’ historic presumptions on battery replacement costs, battery and charging system development over the last decade especially has dictated that garages invest in extra training and hardware. It is worth your while. Provided that you have prepared appropriately, you can reassure customers that you are capable of replacing batteries on even the latest models, as well as helping to secure a profitable area of the market that is certain to grow.

Resetting the BMS is performed via the EOBD socket. Pictured is the EBT-780, part of ECOBAT’s ONE BOX kit.


About Autotechnician
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