We have just endured one of the coldest winters on record. As with many car components, batteries do not perform at their best when cold. In fact, at zero, a battery can only provide 65% of the cold start performance it can provide at + 15c. If the battery is old and tired, and or not fully charged, then the performance drop is even greater. This is why batteries fail in cold conditions.
The weather also highlights how car batteries will have a much tougher time in the future, unless the correct technology is used when replacing a battery. Micro-hybrid technologies (such as stop-start, brake energy regeneration and alternator passive boost) is having a profound effect on the battery market.
It is expected that by 2015 65% of all new cars sold will be stop start. In a micro-hybrid system, the battery moves from its traditional role as a starter battery to an integral part of the vehicle. It needs to maintain all the electrical systems in the car when it is switched off, while coping with intermittent charging and deep cycling.
As ever, never choose a battery on price, first ensure the replacement battery is of the same technology and specification as the original, then consider price.