Bosch batteries and chargers

Bosch reports that members of its battery range landed both ‘Best Buy’ and ‘Recommended’ accolades in this year’s Car Mechanics magazine awards. The tests used to determine the best product in each category looked at usability, durability, capacity and cranking. The Bosch S5 Silver Plus, which features 610 cranking Amps, a 63AH capacity and a five-year warranty, was determined the ‘Best Buy’ – with the maximum score of 20/20, while the – Bosch S4 Silver, with 540 cranking Amps and 60AH capacity, received a ‘Recommended’ accolade.

Both award winners are part of the Bosch S-series, with the S5 offering the highest performance ranking for traditional petrol/diesel vehicles. Topping the S-series are batteries intended for vehicles using micro-hybrid technology, a fuel-saving feature increasingly seeing light of day – Bosch anticipates that 65 per cent of all new cars will utilise this by 2015. One popular micro-hybrid system is start-stop, which can reduce fuel consumption by up to eight per cent when used in urban areas where traffic lights are common. Other micro-hybrid technologies include ‘brake energy regeneration’ and ‘alternator passive boost’.

Yet although they save fuel and reduce emissions, micro-hybrid systems place additional strain on other components in the vehicle: one component that is extremely affected is the battery. In a micro-hybrid system the role of the battery changes from its traditional role as a starter battery to an integral part of the vehicle, as it needs to maintain all electrical systems in the car whilst it has switched-off whilst also coping with intermittent charging and deep-cycling.

Due to the additional requirements micro-hybrid systems place on the battery, superior battery technology – AGM – is called for. In AGM, structural changes within the battery enable it to cope with three to four times the number of cycles (stop-starts) as a traditional battery, and it is able to cope with higher charge acceptance (for quick charging through brake energy regeneration). In addition, these AGM batteries are able to operate at much lower states of charge (for frequent start-stops) and have higher cranking performance (to deliver the required power to turn the car over even in cold weather). Bosch currently offers two AGM batteries as part of its S6 range and three further batteries will be added within the next 12 months.

Some smaller micro-hybrid vehicles will only use start-stop technology and hence place a lower strain on the battery than those that also have ‘brake energy regeneration’ and ‘alternator passive boost’. To cater for these, Bosch has developed EFB (enhanced flooded battery) technology, which it describes as being a “halfway house” between a traditional lead-acid battery and the AGM; its price positioning is expected to reflect this.