Batteries are feeling the heat! We explore why the lifespan of a battery reduces in hot temperatures.

Commonly, it's presumed that cooler weather is a cause of battery failure, but we do not often associate warmer climates and climbing temperatures with battery failure. Whilst Britain battles with severely hot temperatures, we investigate what impact this has on our automotive batteries, and why the lifespan and performance of a battery is taking a hit.

So, what do we already know about how temperatures affect batteries? We know that when batteries get cold, the chemical reactions are drastically slowed down. A slower chemical reaction can lengthen the life of a battery through reducing the degradation of normal usage over time, but also results in lower battery output capability. When temperatures plummet, it often seems as though our batteries stop working. But in fact, low temperatures are only exposing underlying degradation problems with our batteries.   

Now let us explore what it less commonly known – the effect hot temperatures have on batteries. Whilst buckling, paste shedding are some of obvious physical defects that occur in hotter weather, something far more sinister is bubbling below the surface.

As temperatures increase, so does the speed of the chemical reactions within our automotive batteries. This causes an increase in the battery output and can vastly increase the speed at which the battery degrades.

Something to keep in mind, is that the difference in regional temperatures and climate, means that the lifespan of batteries within commercial fleets or emergency service vehicles, will differ depending on location. If we assume that a battery is getting a normal/average amount of use, the temperate difference between regions can impact of battery life expectancy drastically:

Regional Climate 

Average Battery life expectancy 


55 months 


45 months 


40 months 

Extreme Hot 

30 months 

This shows that extreme hot weather, has more of a detrimental effect on batteries than any other weather condition.

The above table assumes normal/average battery usage, but because usage has been significantly reduced during the recent global pandemic, fleet and emergency vehicles that are normally driven daily and for prolonged periods of time, are sitting stationary inside hot garages and units for longer than expected. Unfortunately for workshop and fleet managers, constant battery self-discharge is inevitable. On a ‘normal’ day, at average temperatures, around 1/100 of a volt per day is lost in a fully charged battery. If we extend that to a month, then the battery is likely to lose close to one third of its charge. When temperatures begin to rise, battery self-discharge rate increases, and the risk of sulphation creeps up. With vehicles experiencing less use, it is likely that high volumes of fleet vehicles are stored with a low state of charge, therefore risking premature battery failure

If the vehicles within your fleet have been stationary for a prolonged period, we strongly advise testing the battery to understand the battery status, giving you the chance to charge it before it’s too late, leaving you with a costly replacement being the only option. A good battery maintenance routine is key to ensuring the health of vehicles, year-round. To discuss opportunities on how we can help improve your battery maintenance programme, please get in touch.


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