Can a BSG boost your fuel economy?
Belt-starter generators aren’t a new idea, but they’re becoming more popular in saving gas
BSG stands for belt-starter generator, among other acronyms, and while it’s not a new idea, it’s seeing new applications in the fight for improved fuel economy. The feature is a high-powered alternator with an extremely robust drive belt that can actually return power to the engine, rather than robbing it.
Fiat Chrysler, for example, is offering it on its all-new 2019 Ram trucks and Jeep Wrangler as a factory option. On takeoffs and moderate to hard acceleration, this unit can help spin the engine crankshaft via its pulley and a drive belt connecting to the engine. On deceleration, it can help to recharge the battery and supply electrical needs of the vehicle. This latter feature is pretty much what alternators and generators were designed to do all along.
You can file this and other features, such as automatic start/stop systems, under the mild-hybrid category. They won’t turn your gas guzzler into a Toyota Prius, but they can improve fuel economy by between five and 15 per cent, depending on engine displacement and operating conditions. The systems are computer controlled, switching seamlessly from supplying electrical power to adding a boost of torque to the engine. They’re primarily designed to provide this boost in stop-andgo driving or under heavier engine loads at speed, where fuel economy usually suffers the most.
An added benefit of BSGs is their high-power output based on 48 volts. This gives engineers the freedom to convert other engine power-robbing units, such as A/C compressors, water and power steering pumps, from belt driven to electric operation. By removing these units from beltdrive system, fuel economy gains of about 10 to 15 per cent are possible, or keeping power steering assist at its maximum under the same conditions. As well, engine cooling systems can operate in a much more consistent manner as water-pump speed can be independently controlled to match varying needs.
But what if you’re not ready to trade in your existing ride for a mild-hybrid model? There may be hope: SEG Automotive, an international company working in five continents that has been in the starter/generator business for more than a century, is developing a BSG unit — called a boost recuperation machine — that can be retrofitted into existing vehicles with relatively minor wiring modifications. SEG has managed to shrink its recuperater to almost that of a normal alternator.
Let’s put it this way: if you were operating a fleet and someone promised you 10 per cent in fuel economy gains with a simple bolton application, what would you be willing to pay?