DIY Mild Hybrid?

[GasSavers_maximilian]

Since a mild hybrid is typically just a beefed up starter motor and some control electronics to turn the engine on and off appropriately, how hard would this be to do yourself? Providing you have room for a bigger starter motor it doesn't seem like it should be that difficult. Not something I could do with my warranty, but it's an interesting idea.

[GasSavers_RoadWarrior]

It isn't usually a starter motor in the usual position though, it's a motor/alternator on the belt side, with extra beefy belts. Could probably retrofit a system by removing AC or power steering or conventional alternator to make room to fit a larger motor. Don't think you could just use a starter motor from a larger vehicle though, because they don't have the cooling capacity for anything more than very intermittent use, and constant stop start in city traffic may overheat them.

[GasSavers_maximilian]

Why a motor/alternator? To my knowledge, only the BMW 1-Series actually does regenerative braking. Other mild hybrids just shut the engine off. They have beefier batteries as well, I neglected to add. Not that you couldn't add regenerative braking, but that adds a whole layer of complexity.

Guess you'd need to use a more suitable motor, or maybe add a cooling fan to a bigger starter (would that work?). Electronics should be pretty easy, I'd think.

[dkjones96]

What does the mild hybrid actually do? Assist on starts from a stop? Just restart the engine after you've been stopped?

[theholycow]

I don't think there's a set definition, but most of them kill the engine when stopped and use the enlarged starter to provide instant movement while it's also starting the engine so you aren't waiting for it to start before you can go.

It's EOI without the annoyance.