Banner: why batteries fail

By Categories: Commercial NewsPublished On: Wednesday 1 November 2023

Banner Batteries, whose range includes the Buffalo Bull AGM (pictured), has provided technical insight on some of the key contributors to commercial vehicle battery failure.

“Whilst it’s always going to be impossible to protect fully from the probability of mechanical failure in parts, particularly when on the road and moving, this shouldn’t be the case when it comes to powering up a CV in the first place,” said Lee Quinney, country manager for Banner Batteries.

He highlights the importance of product quality, emphasising the key role of lead as a constituent part.

“The mean weight of a premium OE brand battery when compared to that of a private label product of the same size and specification is a good quality indicator,” he continued.

“In today’s cutthroat world, some manufacturers limit the amount of materials used in battery construction to reduce cost. And as the most costly material used, such batteries often have smaller, thinner and fewer plates, all of which reduce reliability, specification, performance and lifecycle.

“In batteries manufactured in this way, delivering the specified power is often achieved by increasing the acid concentration in the electrolyte used. This too has a direct and detrimental bearing on both performance and lifespan. As longevity comes in the form of striking a careful balance between plate numbers used and acid strength, using a greater concentration creates a sticking plaster effect, as increased internal corrosion will result and negatively so.

“In summation, the three definitive phases of a battery’s life cycle, Formatting, Peak and Decline, are all compromised when plate numbers and lead content are reduced, and acid strength increased.”

Turning to the causes of failure, says Lee, battery wear and tear is a natural phenomenon whilst in service.

“A battery loses a small amount of its ability to supply current (CCA) each time it is cycled,” he explained.

“The deterioration of a battery caused by wear and tear can be best explained as follows: a battery in good condition but in a discharged state will be able to supply specified levels of CCA when fully charged.  A battery that is in poor condition has a corresponding reduced ability to supply CCA but will still indicate a fully charged state.”

Weather also has its part to play on performance, Lee adds, as transport operators know only too well.

“Starting performance in cold weather conditions is normally associated with battery plate ageing and deterioration, reduced chemical reaction speeds, and greater starter motor power requirements,” he said.

“Charging system efficiency is also reduced.

“On the temperature front, then whilst at ambient a fully charged battery has approximately 100 per cent of its power available for cranking, this drops to 66 per cent at 0 ºC and 40 per cent at -20 ºC.

“Equally damaging to a battery’s health is hot ambient and under bonnet temperatures, as these lead to accelerated battery ageing, plate corrosion, and increased self discharge rates and electrolyte use. A 10 ºC rise in battery operating temperature doubles the self discharge rate from approx 0.1 to 0.2 volts per month.”

Plate sulphation is another factor to consider, adds Lee.

A natural element of battery discharge, this process coats the battery’s plates in lead sulphate (PbSO4) when it reaches 12.40V and below. It is normally attributable to poor stock control and recharge procedures, and undercharge conditions that usually emanate from loose drive belts and/or the existence of high resistance in cables and terminals.

“If a battery is quickly recharged the lead sulphate is displaced from the plates and the battery will perform normally, however for those allowed to stand in a discharged state (<12.40V) for a period of time, the deposits on the plates can crystallise and harden, which reduces battery performance. “

Acid stratification and deep cycling is another concern.

“This condition prevails when acid in the electrolyte solution concentrates at the bottom of the battery cells,” he said.

“In general it occurs if a battery is kept at a state of charge (SOC) below 80 per cent and never receives a full charge.

“It is more common in the cold months as it not only becomes more difficult to charge a battery due to its large thermal mass, greater internal resistance increases the time required for it to become fully charged. This is also exacerbated by short driving periods and distances, particularly those involving high levels of electrical consumers.

“Whilst a battery that is cycled normally loses a small amount of active material from its plates, those subject to deep discharging (in excess of 35 per cent) and rapid recharging – taxis, delivery vans and constant shift pattern vehicles – can quickly result in rapid loss of performance and premature failure.”

Further contributors to battery failure identified by Lee include overcharging, undercharging, short circuits, dead cells and internal breaks.