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Old 06-19-2008, 07:21 PM   #11 (permalink)
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Does the prius use an alternator along with its regenerative brakes? I assume it does... but does it do so in an efficient or interesting way if so?

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Old 06-19-2008, 08:48 PM   #12 (permalink)
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Don't know about the Prius specifically, but the Insight does get all its electrical power from the motor/generator. It charges the 144 volt main battery, then a DC/DC convertor shifts some down to 12 volts (actually around 13.6, to keep the small 12 volt battery charged) to run the standard electrical accessories.
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Old 06-25-2008, 12:17 PM   #13 (permalink)
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ive asked similar questions for my crx project... ive been looking at the aviation world... there are a few companies that offer 35-45 amp alts.(some higher) that weigh in at 4-6lbs thats shaving some 10lbs off my honda alt... and only losing 20amps output... but im also going minimal on my electronics... my massive stereo system will include: an ipod and plug speakers... since im running a "lighter" alt the 6lb battery i found will work perfectly for the system also
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Old 07-04-2008, 11:50 AM   #14 (permalink)
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Running the engine just off the battery will shorten the battery life.

Draining down the battery and then periodically turning on the alternator to recharge it might shorten the life of the alternator. (A new ACDelco alternator for Unklecueball's '06 Aveo is $390 per RockAuto.com)

Modern cars like the Aveo already use the smallest, lightest, lowest output alternator possible.

Turning off major electrical accessories when stopped at a light would increase gas mileage because the engine would not have to automatically speed up to avoid stalling. But turning off headlights at night might be risky!

Last edited by TomT; 07-04-2008 at 08:04 PM..
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Old 07-04-2008, 12:10 PM   #15 (permalink)
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Like others have said, reducing accessories reduces the magnetic field and thus resistance within the alternator, raising FE. My friend had a HUGE (like 2000W) stereo in his car; when he turned his amp on, it was like a "slowness switch".
FYI - a car's electrical system (necessary stuff like ecm, ignition, sensors) is typically somewhere around 300-400W without lights, radio, etc. Newer cars are more than older cars I'm sure.

Noone's mentioned using a deep cycle battery and a plug-in charger. This is what I'm planning on doing; running a kill switch on my car and when I'm commuting 15 miles to and from work, running on straight battery when I can. The alternator sees no extra duty and the deep-cycle battery is made to be discharged and recharged with minimal sulfation. Electrical power is more efficiently produced in a power plant than in your car, and with current prices, it's way cheaper too!
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Old 07-04-2008, 06:59 PM   #16 (permalink)
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Take a good look at anything that uses electricity in your car, and remember that every single milliwatt you is energy derived from your gasoline. Use less power, use less gasoline.
Come on now. Get a grip. You guys are "SPLITTING HAIRS" worrying about alternator drag and it's effects on MPG.

These alternators are so small to begin with that they do enough just keeping your battery charged.

If you're willing to risk a DEAD battery (out in the middle of nowhere) for the sake of increasing MPGs. Knock yourself out.

Medication for OCD is cheaper than AAA and a new battery. Just think of all the time/energy/$$ you'll spend just to save (1) MPG.
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Old 07-05-2008, 11:45 AM   #17 (permalink)
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Medication for OCD is cheaper than AAA and a new battery. Just think of all the time/energy/$$ you'll spend just to save (1) MPG.
Time/Energy shouldn't count - this is a hobby for most of us, probably including you!
That said, the $$ aspect of this is very important to many of us, and it's what will allow us to spread the word on Ecomodding.

I'm personally on a pretty tight budget. All the mods on my car have to be cost effective if I'm going to do them. I'm willing to invest money if it is likely to pay itself off in ~6 months at $5/gal fuel. Most of my mods so far are with free stuff I got, stuff I found in the trash, or things I had lying around. Time invested is my only cost, and it's fun!
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Old 07-05-2008, 02:03 PM   #18 (permalink)
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Saving a few 'milliwatts' of power is ridiculous. It takes a whole 746 watts to equal 1 horsepower. A few thousandths of an HP is not worth considering. Just slowing down a fraction of a MPH will gain you much more.

Also, a higher output alternator should not put any more load on your motor. The post earlier that said that an alternator will operate like a motor and turn against your gasoline engine is incorrect. Therefore it is also incorrect to assume that a high output alternator will be more of a load (backwards turning resistance) on your engine. A high output alternator will only be more of a load than a standard output alternator IF or when your car's electrical system is demanding the extra output.

I think there is more misinformation floating around in the field of electrical circuitry than any other part of auto mechanics. I also think that it is in part due to the incredibly poor wiring diagrams that are in many automotive service manuals. They are often only good for identifying wire colors to the various components. They are very poor at depicting an actual circuit as such and this I believe contributes greatly to the misunderstanding of what a circuit is and how electricity works. Anyway, that's my opinion ;-)
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Old 07-05-2008, 06:51 PM   #19 (permalink)
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The alternator "mod" I'd like to see would involve back-driving the unit with power to turn it into a motor. Charge up a super-capacitor when slowing down and use that power when accelerating -- sweet!

It'd be complicated, but not impossible. You'd have to have a variable frequency inverter drive the coils, not something I'd know how to do.
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Old 07-08-2008, 03:27 AM   #20 (permalink)
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Time/Energy shouldn't count - this is a hobby for most of us, probably including you!
That said, the $$ aspect of this is very important to many of us, and it's what will allow us to spread the word on Ecomodding.

I'm personally on a pretty tight budget. All the mods on my car have to be cost effective if I'm going to do them. I'm willing to invest money if it is likely to pay itself off in ~6 months at $5/gal fuel. Most of my mods so far are with free stuff I got, stuff I found in the trash, or things I had lying around. Time invested is my only cost, and it's fun!
I couldn't agree more.

That's why I posted what I did. If one was to run down your battery out in the middle of nowhere (because of "trying" to save $$ on fuel), you would be LOSING much more $$ in the process.

Like I said, a tow from AAA ($60+) and the time/energy (also worth $$$$) to recharge/replace one's battery ($50+) HAS to be taken into consideration.

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