Written on January 27, 2016 at 1:50 pm
What Might Be Round The Corner For Members?
Although workshops that deal with the service and repair of passenger cars will be becoming more familiar with micro hybrid vehicles (those fitted with a stop-start system), to date the technology has not really been relevant in the heavy duty sector.
Granted, some light commercial vehicles (LCV), such as the Mercedes Sprinter and the Ford’s Transit ECOnetic, incorporate a stop-start system, but beyond these and similar LCV examples, the typical CV workshop has had little exposure to the technology. However, with the launch of Cummins’ new stop-start system for its ISB engines, things could be about to change.
Lets first go back to basics, the logic behind a stop-start system is simple, an engine doesn’t use fuel or produce greenhouse gas emissions when it isn’t running, so the most effective way to reduce fuel consumption and emissions it to only use the engine when it is actually needed.
This technology therefore delivers on two fronts: first, a reduction in the fuel consumption of the vehicle saves fleet operators money and second, lower exhaust emissions contribute towards global greenhouse emission targets.
However, to put this perfect logic into practice requires incredibly complex design and advanced systems, not just for the mechanical components that physically stop and start the engine and the electronics that control the process, but also for the batteries that provide the stored energy to start the engine over and over again.
Pre the stop-start revolution, excessive electrical demand without the engine/alternator charging a typical lead-acid battery, would risk leaving it without sufficient capacity to restart the engine and in addition, a state of discharge to that extent would be detrimental to the overall health of the battery. This is because these batteries are not designed with a high cyclic capacity – the ability to go through a charged, discharged, charged ‘cycle’. Instead they are designed to take a high discharge load to start the vehicle, followed by a constant charge feed while the engine is running.
In contrast, modern batteries such as the Lucas and Numax Supreme CV are designed with a high cyclic capacity and are therefore ideal for the demands of high performance vehicles with large power requirements, as well as for those that feature a stop-start engine, like the new Cummins unit.
In addition to starting the engine, the battery in a typical stop-start vehicle is used to power all of the vehicle’s electrical demands, without necessarily being charged, because running the alternator uses energy and therefore has a detrimental impact on fuel consumption and exhaust emissions.
As a result, the vehicle’s battery management system will allow the battery to discharge to a predetermined level – obviously still with sufficient capacity to restart the engine – before it engages the alternator in order to recharge the battery for the process to continue once again.
Alongside the alternator, some stop-start vehicles are also designed to harvest energy from other parts of the vehicle, such as when braking with a regenerative braking system, which gathers the otherwise wasted energy required to halt the vehicle and stores it in the battery, thus reducing the load on the alternator.
To ensure the reliability of its new engine, Cummins has subjected the stop-start system to rigorous testing during a validation programme that has included in excess of four million stop-start cycles. Bearing in mind that it anticipates an engine used in a vehicle driving in London could stop and start between 60 to 80 times an hour, clearly the vehicle’s batteries need to possess huge cyclic capacity.
The Supreme CV, which is available to G-Truck members through Manbat Ltd, under both the Lucas and Numax brands, incorporates the high quality internal components necessary to deliver this level of performance.
High output capacity and cyclic performance are linked, both through the design of the lead plates and their number. The Supreme CV features multiple plates that have been punched out of solid lead sheet to provide the most efficient method of power transfer.
Although other manufacturers boast about plates with a grid-like formation, many ‘roll’ these plates, which can weaken the joints and means they are prone to corrosion, with the subsequent loss of performance.
There are however, no such fears with Supreme CV, which means that G-Truck members can supply the workshops with confidence.