Alternator v. no alternator - 10% gain @ 70 km/h - Page 16 - Fuelly Forums

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Old 04-03-2007, 09:03 PM   #151
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Originally Posted by Brock View Post
The problem is with solar they are rated at ideal sun angle at solar noon. Once you get that inside the car you will loose 10-30% right off the bat for going through another layer of glass (likely UV coated). Then top that off with being shaded or tilted at the wrong angle and you would be lucky to get 50% of rated power even with full sun not to mention cloudy or shaded conditions.
Good points. Especially since I think my car windows (including the back/hatch window I was thinking of putting solar cells under), are ever so slightly "tinted". Not a lot of tint mind you, but probably enough to make a little bit of difference to a solar cell array.

Oh well. I guess I'll just hold off for right now (as those extra power losses you mentioned, are enough to make the 1 amp array I was looking at to be of "questionable value" in my car application), and instead wait for solar arrays to ether come down a little in price or get noticeably more "efficient" (or both).

I do know that there are already solar arrays on the market that peak at around 20% efficient (i.e. in the 3 to 5 amp range, for something that fits in the back of my car, instead of the 1 amp unit I was looking at), although naturally they are the most expensive solar cells (and also the ones hardest to find, as they seem to be in high demand worldwide). And even more efficient (in terms of power produced per surface area used) solar arrays are already in the research stage. Meanwhile solar arrays are also (slowly) getting cheaper to produce over time.

So in the long term, better efficiency (in terms of power for surface area used) and cheaper (to buy) solar arrays will eventually hit the market. It's just a question of "when". For the moment, high demand (worldwide) for solar is keeping prices up (and will likely keep some solar arrays in short supply for much of 2007), but long term the trends are clear (cheaper and more efficient solar cells).

OTOH that high demand isn't all bad, as it's also encouraging solar cell R&D, which should eventually increase efficiency and/or lower prices. And with "already on the market" solar arrays already being "close" for what we need to remove (or at least greatly reduce the use of) alternators in cars, at some point in the future using solar in our cars (if only to make the ICE more FE) will start to make a lot more sense. I guess we are just not quite there yet.
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Old 04-04-2007, 08:48 AM   #152
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There is something to "topping" off a battery before driving though. I do this all the time from my home solar array, which I also use to charge my second battery. Basically I use two older marine batteries and swap them out when I get home and put the used one to charge on from the solar array.

In case anyone missed it I use one of the old marine batteries to feed a 1200w Trace inverter, which in turn feeds an Iota DLS 55 amp charger that is connected to the starting battery with the alternator wire disconnected. So my inverter / charger acts as the alternator charging the main battery. Again my problem is I have glow plugs that warm up the coolant pulling 60 amps until I hit about 110-120F on coolant temp. In winter that is 5-6 miles, right now about 3 miles and in the heat of summer that is a mile or so.
Brock-
Is there an advantage to having the inverter/charger between batteries compared to just attaching the marine battery to the electrical system?

I have been using a 5 watt solar panel and solar panel controller to "top-off" my battery while the car sits during the day. Engine off coasting with the headlights on has been hard on my battery. It is a small AGM which I bought for autocrossing because it only weights a few pounds, but it has little reserve capacity.
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Old 04-04-2007, 06:29 PM   #153
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Bill, I can take a stab at that answer...

If you just attach the batteries in parallel, you increase the capacity, but you still have the same voltage. I think Brock's ECU had a hissy fit when his voltage fell below a certain level. (My car runs OK unless I let the voltage sag very low - like below 11 v - and it doesn't throw a code even when that happens.)

With the DC DC converter, he gets to keep feeding the main battery 13+ volts, keeping that battery, and the computers happy (at the expense of somewhat less total capacity, lost to some inefficiency in the DC converter).

My setup, 2x 6v connected to the 12v starting batt is simpler, but it's also harder on the 12v batt, since I'm discharging it regularly. Brock's will last longer than mine.

It's safe to say to anyone doing lots of engine-off stuff, or running without the alternator: you will cause your battery's premature death, relatively speaking.

Probably more expensive in the end than the fuel you'll save, unless ... a) you have a source of cheap batts, or b) fuel is really expensive, or c) you care more about high FE numbers, and are willing to "pay" in batteries to get the results.
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Old 04-04-2007, 09:10 PM   #154
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Thanks for the help, that makes sense.
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Old 04-05-2007, 07:34 AM   #155
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Yes, just putting extra batteries in parallel in my car the ECU complains and "throws codes" telling me there is an alternator problem. With the way I have mine it keeps the starting battery up at like 13.6v to 14v except right after starting with the coolant plugs running, then I am about 12.4v or so.

And yes the cost savings are really not worth it for the typical driver. In my case I literally had all the parts, extra batteries, big true 55 amp charger and good sized 1200w inverter sitting around. Otherwise the inverter is about $100, charger is about $180 and the batteries new would be about $55. Again this keeps my starting battery healthy compared to just running in parallel with a second battery.

I have found in my case I use about 500w to go to and from work from the second battery bank. Not sure what that turns in to fuel wise. I think a gallon of gas/diesel hold approximately 5kw? So it should be saving me about 1/10 gallon of diesel per trip? I see about a 10% gain on SG running this way.

And 500w should cost me $.05 charging from the grid (usually use solar) and 1/10 gallon of diesel would be $.30. So I save a quarter a trip
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Old 04-05-2007, 11:26 AM   #156
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The problem with these is three: 1) they have limited efficiency, 2) like solar, they get to cost a lot once you have enough of them to be useful, and 3) they don't actually work on heat, they work on heat differential. That means you need to have enough 'hot' surface area to hold the requisite number of the devices and some way to carry that heat away (heatsinks, etc.) to create a temperature gradient on the other side of each device.

I've done the numbers and besides the cost, it's not clear to me that while the exhaust temperatures are high enough, exhaust probably won't give you enough overall heat to make it worthwhile. Engine coolant might have enough heat, but the temps are probably too low. YMMV.
I've seen 85W quoted for the max temp diff. (400F peak) of $12 units iirc. The peak temperature is way less than peak EGTs, so they would need to be placed farther down the exhaust and the peak temp there checked, but as long they didn't exceed the max temp, and put out ~5-40W each, I think they could work with aggressive power cuts from led lighting, etc. For someone who does nothing but city, they probably aren't suitable, but for mostly highway, with lots of air flowing over a hot exhaust...

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Alright, I did some searching, and there are some that can provide 85W, but they can't go above 400 degrees F, so they might have to go a bit far down on the exhaust. But... they're only ~$12 a piece
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The factory battery in my '94 is alive and well. How many batteries would it have gone through by now with alt off operations and at what cost?
A yard I used to live by sold used/tested batteries w/ a month warranty for $15 with a $4 core. Someone should find out!
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I think if i could get that type of FE i would have no problem driving a dildo shaped car.
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Old 04-05-2007, 08:42 PM   #157
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Water pump belt

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Bill, I can take a stab at that answer...
METRO,
What are you using for a water pump belt this time? I bought some Round urethane belting from McMasterCarr but have not tried it yet. They have quite a few choices. I was going to buy a large urethane O-ring but found this belting.

http://www.mcmaster.com/ You might search for urethane belt if curious.

I am considering alternator less but have not done any experiments yet.

Ernie
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Old 04-12-2007, 08:11 PM   #158
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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.
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").
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Old 04-12-2007, 10:03 PM   #159
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DracoFelis wrote:"when you have fuel cutoff when costing in gear, the alternator still can be generating electricity using your momentum."

This is why I installed a switch to turn on the radiator fans. I use it when I'm slowing/stopping to help cool the motor so the fans don't come on if I'm stopped too long. I just have to remember to turn it off as well. It's especially helpful in managing engine heat since I have a partial grill block.
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Old 04-13-2007, 08:18 PM   #160
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Anyone consider rigging up a lock and release pulley on the altenator fan belt?

Place a longer than needed belt on and have a pulley attached to a cable that when pulled would lock into place putting tension on the belt thus allowing the alt to work. Then at the press of a button or whatever else you can think up of unlock the pulleys catch and allow the belt to loosen off of the alt.

Might be way off but I'm not a spark chaser. More of a hardware person myself.
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