You show the same rebuild kit for 80 amp or 140 amp options on my BMW alternator?

Question: You show the same rebuild kit for 80 amp or 140 amp options on my BMW alternator. I have a 1995 BMW 525i with 140 Amp alternator. Wouldn’t an 80 amp regulator burn out?

Answer: Hi, the voltage regulator does not create, handle or limit the maximum amperage output of your alternator. Instead, it acts as an "on-demand" electronic switch that controls a very small 3 to 5-amp current fed to the alternator's internal electromagnet (the rotor). Because the control current required to wake up the electromagnet is nearly identical on both the 80-amp and 140-amp compact Bosch units, the exact same regulator safely commands either size.

The regulator only monitors and enforces a stable system target voltage (typically around 14.2 to 14.5 volts). It does this by turning the alternator's internal magnet completely ON and OFF hundreds of times per second (a process called Pulse Width Modulation).

• On a standard 80-amp alternator under a heavy load, the regulator leaves the switch "ON" for longer intervals to maintain system voltage.

• On a heavy-duty 140-amp alternator, the larger internal stator generates power much more efficiently. The regulator naturally adapts by leaving the switch "ON" for shorter bursts to hit that exact same 14-volt target. It actually works less hard on a larger alternator.