alt Hacker NewsThis. Most cars nowadays come with the so-called "smart" alternators that vary voltage wildly depending on the current driving conditions.
One minute you might be accelerating and the onboard voltage drops as the battery supplies most of electricity. Then, as you reach the crest of a hill and start engine-braking, the car frantically tries to convert all the available kinetic energy to electricity, raising the onboard voltage to quickly charge the battery.
>This. Most cars nowadays come with the so-called "smart" alternators that vary voltage wildly depending on the current driving conditions.
Which in practice means that they do a very miserly job charging the battery and are a ton more sensitive to a battery being in less than tip top shape so you can expect your battery lifetime to go down.
But it's a "win" because they pushed the serp belt change outside of whatever interval the reviewers who calculate TCO care about and they saved .000003mph in the process.