Disconnecting alternator from car....

to run on battery only....

Any idea on how much gas this would save?

I noticed a substantial increase in my mpg's when my alternator went, on a
Mazda 929S -- mebbe 15-20%?

If this observation was accurate, it would make sense to hump around a spare
battery, and operate without an alternator -- heh, a kind of hybrid, eh?
--
EA

Existential Angst wrote:
> to run on battery only....
>
> Any idea on how much gas this would save?
>
> I noticed a substantial increase in my mpg's when my alternator went, on a
> Mazda 929S -- mebbe 15-20%?
>
> If this observation was accurate, it would make sense to hump around a spare
> battery, and operate without an alternator -- heh, a kind of hybrid, eh?

I would suspect something on the order of 1/100 gallon per mile
increase. In other words about 0.025%

On Mar 1, 9:31*pm, "Existential Angst" > wrote:
> to run on battery only....
>
> Any idea on how much gas this would save?
>
> I noticed a substantial increase in my mpg's when my alternator went, on a
> Mazda 929S -- mebbe 15-20%?
>
> If this observation was accurate, it would make sense to hump around a spare
> battery, and operate without an alternator -- *heh, a kind of hybrid, eh?
> --
> EA

while you are at it disconnect the A/C belt too!

BTW the battery wouldn't last very long.

"Existential Angst" > wrote in message
...
>
> Theoretically, a good idea. Why not drive the A/C off a sep.
> battery/charging system? No belts req'd.

So you think the AC would require less electrical energy than it requires
mechanical energy? I dont think so.

"hls" > wrote in message
...
>
> "Existential Angst" > wrote in message
> ...
>>
>> Theoretically, a good idea. Why not drive the A/C off a sep.
>> battery/charging system? No belts req'd.
>
> So you think the AC would require less electrical energy than it requires
> mechanical energy? I dont think so.

You'd eliminate frictional losses, belts, bearing wear, etc.
And, if the batteries driving the A/C were separate, so they were not
charged by gas power but hydroelectricity, you wouldn't have thermodynamic
inefficiencies -- a *substantial* savings.

In a sense, you are hybridizing the car "from the other end" -- the
non-powertrain end.
--
EA




>

Existential Angst wrote:
> "hls" > wrote in message
> ...
>>
>> "Existential Angst" > wrote in message
>> ...
>>>
>>> Theoretically, a good idea. Why not drive the A/C off a sep.
>>> battery/charging system? No belts req'd.
>>
>> So you think the AC would require less electrical energy than it requires
>> mechanical energy? I dont think so.
>
> You'd eliminate frictional losses, belts, bearing wear, etc.
> And, if the batteries driving the A/C were separate, so they were not
> charged by gas power but hydroelectricity, you wouldn't have thermodynamic
> inefficiencies -- a *substantial* savings.
>
> In a sense, you are hybridizing the car "from the other end" -- the
> non-powertrain end.

Don't forget the efficiency of the power grid & battery charger, plus
batteries themselves are not 100% efficient, nor are electric motors.
Electric motors have bearings too.

The bottom line is it's a lot of hassle for a nearly unmeasurable gain,
if any, so why bother? Oh, and don't forget the extra weight and expense
of the MUCH larger battery you'd need, plus the weight of the electric
motor to drive the A/C compressor.

Stupid, just like most incomplete analyses of transportation system
efficiencies that don't look at the complete system end-to-end, which is
invariably because of either ignorance, or a political or economic axe
to grind.

> You'd eliminate frictional losses, belts, bearing wear, etc.
> And, if the batteries driving the A/C were separate, so they were not
> charged by gas power but hydroelectricity, you wouldn't have thermodynamic
> inefficiencies -- a *substantial* savings.
>

I doubt very seriously that it would be substantial.
Alternators are about 75-80 percent efficient. Home battery chargers
much less.
I encourage you to try it, but would bet a weeks pay that you would
gain .1 mpg improvement or less.
HTH,
Ben

"Existential Angst" > wrote in message news:4d6e57f6>
> You'd eliminate frictional losses, belts, bearing wear, etc.
> And, if the batteries driving the A/C were separate, so they were not
> charged by gas power but hydroelectricity, you wouldn't have thermodynamic
> inefficiencies -- a *substantial* savings.
>
> In a sense, you are hybridizing the car "from the other end" -- the
> non-powertrain end.
> --
> EA

What you gain one place, you probably lose at another. This is "too
much sugar for a dime".

I agree with the other posters that, whatever you do, you may only
realize a very very small improvement in economy, if any.

"Mark Olson" > wrote in message
news
> Existential Angst wrote:
>> "hls" > wrote in message
>> ...
>>>
>>> "Existential Angst" > wrote in message
>>> ...
>>>>
>>>> Theoretically, a good idea. Why not drive the A/C off a sep.
>>>> battery/charging system? No belts req'd.
>>>
>>> So you think the AC would require less electrical energy than it
>>> requires
>>> mechanical energy? I dont think so.
>>
>> You'd eliminate frictional losses, belts, bearing wear, etc.
>> And, if the batteries driving the A/C were separate, so they were not
>> charged by gas power but hydroelectricity, you wouldn't have
>> thermodynamic inefficiencies -- a *substantial* savings.
>>
>> In a sense, you are hybridizing the car "from the other end" -- the
>> non-powertrain end.
>
> Don't forget the efficiency of the power grid & battery charger, plus
> batteries themselves are not 100% efficient, nor are electric motors.
> Electric motors have bearings too.
>
> The bottom line is it's a lot of hassle for a nearly unmeasurable gain,
> if any, so why bother? Oh, and don't forget the extra weight and expense
> of the MUCH larger battery you'd need, plus the weight of the electric
> motor to drive the A/C compressor.
>
> Stupid, just like most incomplete analyses of transportation system
> efficiencies that don't look at the complete system end-to-end, which is
> invariably because of either ignorance, or a political or economic axe
> to grind.

Yeah, you brought up some minorly valid points, but I don't see a whole
spreadsheet full of numbers supporting YOUR assertions.... or did I miss an
attachment or something??
So because you are a clairvoyant genius, you KNOW there wouldn't be any
payoff, right?

Now, as to the other much more civilized doubters, yeah, I wouldn't bet the
farm on anything.
But, ito of efficiencies, I'm not talking about alternator efficiency or
efficiency of any components per se, but rather the efficiency of the *gas
being combusted* to drive the alternator. A gas engine is, bottom line,
about 30% efficient, and possibly much less.

So getting *anything* off the "gas grid" is a 70+% savings, right off the
bat.
How much the inefficiencies of alternative methods might eat into that, such
as the charging efficiency, battery weight, etc remains to be evaluated, but
I can't see that stuff eating THAT much into that immediate 70% savings from
the thermodynamic losses.

Again, I don't know exactly what the frictional losses are in these belt
drive systems, but I do know those belts are effing TIGHT, and a 1 hp loss
doesn't seem that unreasonable. And 1 hp is a *subtantial* fraction of what
it takes to keep a small car going at 60 mph -- not far at all from that
15-20% hike in my mpgs that I thought I observed years ago.
And, THAT was just with a blown alternator, not with a removed belt!!

Heh, it's an easy enough experiment to try, right? Just keep a spare
battery in the trunk....
Altho, I was not able to find out how to "unplug" the alternator on my '04
Nissan Frontier pickup, so I have not yet been able to re-do the experiment.
--
EA





>
>

On Wed, 2 Mar 2011 14:33:20 -0500, "Existential Angst"
> wrote:


>
>Heh, it's an easy enough experiment to try, right? Just keep a spare
>battery in the trunk....
>Altho, I was not able to find out how to "unplug" the alternator on my '04
>Nissan Frontier pickup, so I have not yet been able to re-do the experiment.

I used to remove the A/C clutch electrical plug every fall on my cars,
and tape it out of the way.
GM vehicles.
Didn't want the compressor running in defrost mode in the winter,
because I didn't need it to clear the windows.
I've heard since that it's good to run the compressor in the winter,
but pulling the plug never caused me an difficulty I know of.
Probably saved some gas doing that.
Don't fool around with your alt. That's a dead end.

--Vic