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Old 09-04-2018, 05:05 PM   #1 (permalink)
Daox
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Location: Germantown, WI
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CM400E - '81 Honda CM400E
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Swarthy - '14 Mitsubishi Mirage DE
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Calculating 'regen' with an alternator

Just this past weekend, I finished my alternator delete on my Mitsubishi Mirage. The next phase of the project is to allow the alternator to be re-enabled during braking events to essentially get some free charging.

But, how much power can you possibly get from an alternator during braking only? Lets find out!

The Mirage's alternator is a modest 85A alternator. In a forced mode, I can make it put out 15V. That gives us a theoretical max output of: 85A * 15V = 1275W.

Lets estimate that when you come to a stop, you 'brake' for about 5 seconds. Thus, you get 5 seconds of charging per stop. More math shows us that 1275W * 5 seconds = 8925 watt seconds. Convert to watt hours and you get 2.48WH. Again, do some conversion to bring that back to something we more so understand. Divide that 2.48WH by 12.5V to get .2 amp hours. .2 amp hours of regen per stop with the alternator on this thing absolutely maxed out. Doesn't sound like a ton eh?

But, that is only for one stop. I have a possible 10 stops on my way to work. Lets say I'm having a bad day and have to stop at every single one, and I brake for the same amount of time on each one. Math is pretty easy at this point. I regen 2Ah. Still not much...

I'm about to head home for the day. I'm going to try to keep track of how long I brake per stop and get a better idea of how much I can take advantage of re-enabling the alternator. At this point, it seems very questionable as to weather its worth it,

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