Quote:
Originally Posted by bekind
It works but like others said it is really hard to tell.
Basically it works by disengaging the alternator which under normal use presents some parasitic loss as it is tied to the engines crank via a belt. When you are coasting, the alt disengages and the energy is generated at the wheels.
We are moving towards a world where vehicle accessories will be driven electrically and not mechanically via a direct link to the motor. A few years back all cooling fans were driven off the serpentine belt but now most are moving toward electric fans. Same with the alternator and soon probably even the A/C.
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In fact, the alternator is mechanically engaged all the time. It's output is electronically controlled so that once the battery is charged to about 80% of maximum storage, the alternator is electronically switched to a low charge condition during constant speed cruising and then switched to a very high charge condition when the driver releases the throttle and/or brakes the vehicle.
This reduces the engine load during regular driving and recovers energy during braking that would otherwise just add to the brake system heat load.
If the battery drops down to a 50% charge level, the system switches to a constant charge mode like a conventional alternator system. This will typically happen, only if you drive for short distances and start the vehicle a lot without allowing enough driving time to fully recharge the special, deep cycle saturated mat battery.
On the European fuel driving cycle, the BER system results in a 3% fuel efficiency increase. It's a small, but significant advance and does really work.
The downside is that it requires a special high output, modulated alternator, and a larger, more expensive battery, so original cost, and replacement costs are higher in trade for the fuel economy advantage.