Quote:
Originally Posted by theclencher
I guess that's the reason I pretty much sat this topic out- carrying the extra weight of extra batteries, doing the extra fiddling around, and compromising your battery's life just didn't seem like they'd work out too well in a benefit/cost analysis.
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As I see it, the problems we are looking into here, are pretty much the smaller version of the problems (and benefits) a full electric vehicle has. And we do know that an EV can be "cost effective" if engineered correctly. So it all comes down to your source of electricity, and what that power source "costs". Let's look at some of the possibilities:
The alternator being powered by the engine:
This is the "default" situation, that we started with. It's initially pretty cheap to get an alternator, and in fact most cars already have one installed! And in most cases, the alternator can supply all the power you want (subject to having enough gas). The main disadvantages of the alternator are the extra fuel used (due to engine drag), and the extra weight.
Grid charging the starter battery:
This is easy to do, and does save fuel if you disconnect the alternator. But a basic starter battery will die too quickly if you "deep discharge" it like this. So the costs of replacing the battery is high. And you also pay some for the electricity to charge it. Finally, range is limited (however you can use the alternator as a "backup" for when you need longer range). IMHO this is NOT a good choice, if only due to the costs of the battery replacements.
Grid charging better quality batteries:
This is essentially a mini-version of what most full EVs do. Just like a full EV, this MAY BE "cost effective" if the right combo of batteries and charging technology is used. However, the initial costs for higher tech batteries (and charging circuitry) may be pretty high (although much less costly than a full EV, as you are still using gas to move the wheels, just offloading some of the secondary "electrical loads" onto better batteries). And, in addition to the initial costs (and possibly also battery replacement costs if/when they eventually wear out), you still pay something for the grid connected electricity.
Solar power:
This one is interesting. Given current technology (and better solar panels are being developed), you can almost get all the power you need (after doing some "power saving" stunts like LED lights) for a small car's electrical using just good solar panels. They will cost you a bit (probably in the $500-$2000 range) for the higher efficiency panels you would need, and you will have to watch how you mount them (to avoid killing your car's aerodynamics), but you can almost get enough power this way to disconnect the alternator. The "gotcha" (other than the costs, and the hassles of mounting the panels without hurting your car's aerodynamics) is that the sun isn't always out (it's not out at night, for example), and the solar panels also won't generate enough power for those times of heaver than average electrical use. So for both of these reasons you need some other "backup" (batteries that can be charged by the solar panels when the car is stopped, the ability to revert to an alternator when you need extra power, etc).
NOTE:
It seems to me that solar as a "partial answer" might very well be cost effective in the near future (and in some case, already). After all, many solar panels are rated as just over 17V (for charging 12V batteries). This should mean that hooking up a solar panel (with diodes to avoid back drain of the batteries) directly to your car's electrical system (without any fancy "chargers") should still cause the solar power to be used FIRST (as that voltage is even higher than the alternator's voltage), and then the alternator and battery make up the difference. Not only should this lower the load on the alternator (saving fuel), but the "trickle charge" from the solar panel, should help keep the battery "topped off" while the car is sitting (thereby helping to avoid having to use the alternator to charge the battery back up when you first start out).
Waste heat from the ICE:
This has been talked about before. It's costly to do (in terms of initial costs), and may also remove heat you want for other purposes (such as heating the cabin in the winter). But it is one source of electricity that may be cheaper (after initial costs are paid for) than using extra fuel to power alternator.
Regen braking:
People like talking about this one, because it seems like "free power". But this power isn't available "all the time", and this power source is also not great enough to handle the entire problem. And it's also been pointed out that better FE drivers brake less (and so would get even less benefit from regen braking than normal drivers). So at best, this can be a piece of the puzzle. Besides which, most cars these days already have limited forms of "regen braking" built in (i.e. even when you have fuel cutoff when costing in gear, the alternator still can be generating electricity using your momentum).
Wind:
This might be able to help some while parked (but may not "worth it" from an initial cost and weight standpoint). However, when driving down the road, any gains in this area will likely be more than offset by the worse aerodynamics. I suppose you could use "wind generation" as a way to do "regen braking" (above), but it doesn't seem to me to be a very practical way.
Turbo generator:
Someone on this forum suggested taking part of a turbo-charger, and hooking it up to an alternator/generator. The idea is to use the "waste gasses" to generate electricity. The idea may have some merit (to at least minimize some of the main alternator's load), but there are some "issues" here as well. It's not exactly clear that such a generator will generate enough power to totally eliminate the main alternator (in the ICE), especially at lower RPMs. Also, it's been pointed out that turbo-charging an engine can help FE (as long as you don't combine that turbo-charging with a lead foot) by allowing the engine to run more efficiently. And you obviously have an either-or situation here (if you get a "turbo-alternator", you don't get a "turbo-charged engine"). Still these are mostly "waste gasses", so using these exhaust gasses for something (either electrical generation, or turbo-charing the engine) may be worthwhile from a FE standpoint.
Other electrical power sources?
Anyone thought of any electrical power sources (small and cheap enough to put in a car) that I've overlooked? If so, what are they, and what are their pros/cons?
So where does that leave us? IMHO the alternator will be around for quite a while, if only as a backup. However, there are some technologies that can be retrofitted to a car (solar cells, better batteries, etc), to generate/store at least some of the electricity you would otherwise generate from the alternator. And at least some of those other "power sources" are at least potentially cheaper per watt than burning gas (to get that same power from the alternator). So there is some potential for us to retrofit improvements here. An engineering challenge to be sure, but at least the potential for improvement.
And remember, if/when any of us does manage to get to the point that we are consistently, and "cheaply", getting more electricity than we need for our normal use, it's pretty easy to convert other secondary car systems (for example fluid pumps) over to electricity (and thereby lower the load on the ICE even further). While such gains have their limits (unless you install an electric motor, thereby turning your car into a full "hybrid"), they still have at least the potential of offsetting some fuel use with greater electrical power (from other electrical power sources).
BTW:
I'm not rushing out to modify my car quickly. I'm a full time computer professional, and don't have the time (or money) to be making wholesale changes to my (working) car. However, I am slowing making changes/improvements, as I have free time (and a little money for the "upgrade"). For example, I've already converted most of my car lights over to LEDs (and yes, the lower electrical usage of the LEDs, does seem to help some). And I'm pretty sure I'll eventually get around to installing a solar panel and/or add a battery pack to my car (I just don't know when yet). Still, the improvements I do make, I generally make gradually (so I can at least partially "pay for my improvements" with better FE, before moving onto the next "fix").
I guess we are just not quite there yet. 
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