Petrol and diesel engines have depended on their batteries ever since the invention of the starter motor. They’re the lifeblood of what makes your fleet lorry, truck, van or car start, activate its alarm, arm its central locking and, on some small level, power its electrical appliances.
Batteries convert chemical energy into electrical energy. Every start, trip, engine idle and load affects its performance. It means that one week, your pickup truck might start fine; the following Monday, it chokes and just about starts, and by Wednesday, it’s a non-starter.
Of course, as a fleet manager or technician, you see this every day. Thankfully, understanding what shortens a battery’s lifespan leaves you free to implement simple, cost-effective fixes, and that’s what this article is about.
Temperature extremes
Batteries, like us, are fussy about the weather. There’s a ‘just-right’ range of around 20°C to 25°C. Anything hotter or colder, and batteries struggle in different ways.
Hot temperatures, which could be caused by the heat generated inside your engine bay, not just the environment, accelerate plate corrosion in the lead-acid batteries your 12-volt or 24-volt systems use. The lead grids or current collectors react with the electrolyte and form rust. As corrosion increases, the chemical reactions that generate electricity can’t happen quite as easily, so your battery and electrical system come under greater strain. Modern AGM or gel-type batteries resist corrosion slightly better, but still degrade faster in heat.
On the other hand, cold temperatures slow down the chemical reactions, but in a different way. The ions flow through the electrolyte between the electrodes, generating a charge. However, as it gets colder, the electrolyte gets more viscous – thicker, like honey. As a result, the ions move more slowly, and this means slower charge and discharge reactions.
In extreme circumstances, such as -40°C and below, the electrolyte can even freeze altogether, especially in batteries with a low state of charge. Thankfully, we don’t usually expect to see such deep freezes in the UK.
What to do: Store your vehicles inside, or at least out of direct sunlight. Use thermal shielding to reduce heat buildup in standing vehicles. Use temperature-compensated chargers (such as the 24-volt CTEX MXT 14 and the 12-volt CTEX XS-7000).
Charging and electrical patterns
One of the biggest killers of battery life is irregular charging. Short trips or turning the engine on to turning it off at low revs with heavy accessory use mean the alternator simply doesn’t have time to recharge the battery. This kind of pattern shows up in delivery drivers dropping off multiple parcels in a neighbourhood.
Over time, this regular undercharging of the battery leads to sulphation, where lead sulphate crystals form on the battery’s plates. With the plates obstructed, there’s less surface area for the charge-producing ion reactions.
Conversely, overcharging, when the charging voltage is too high, means the electrolyte begins to evaporate. That’s because a normal charging session converts lead sulphate and water back into lead dioxide on the positive plate, lead on the negative plate, and sulphuric acid in the electrolyte solution.
Once the plates are fully charged, all the additional voltage can’t further convert the lead sulphate. Instead, the excess voltage splits the water molecules in the electrolyte into hydrogen and oxygen, through a process called electrolysis. That reaction produces gas bubbles and causes water to evaporate. Overcharging also produces excess heat, which, of course, further contributes to electrolyte evaporation.
What to do: Monitor voltage routinely (using testers such as the Midtronics EXP-1000). Ensure consistent charging patterns. Use an automated logging system like ROBIS to track these results.
Driving behaviour and accessories
Although we’ve already alluded to driver behaviour through frequent stop-start trips, let’s focus on it a little more. All sorts of things can negatively impact your battery’s lifespan, including long idles, improper use of refrigeration units, the use of a poor-quality power inverter, or heavy use of lights, heaters or the radio.
Some accessories draw current even when the vehicle is off. Over time, these ‘parasitic’ drains accelerate discharge. For example, some power inverters may demand a constant charge, even when the engine isn’t running. Your drivers might leave the headlights on or forget to switch off the refrigeration when the truck’s empty. Modern telematics units and in-cab electronics can also drain the battery.
What to do: Encourage your drivers and route planners to reduce stop-start trips wherever possible. If not possible, implement more regular scheduled charging and battery inspections, and regularly test accessory load demand.
How can Rotronics help you maximise the lifespan of fleet’s batteries?
At Rotronics, we supply fleet operations with all the battery testing and charging equipment you need. We also offer ROBIS, an online battery management information system, where you can store, analyse and evaluate all your compatible Rotronics battery test and charge readings.
Work with us to get professional battery testers, controlled charging and a clear maintenance plan. You’ll find your batteries last much longer, your drivers keep moving and your business sees a significant return on its investment.
