wind energy on a van roof

[cedric]

Hey<br />I was wondering if they make/sell wind generators that mount on your van roof. Could you charge your batteries while driving?? seems to me there is a lot of wind up on my roof at 65mph

 

[LFM]

If your going down the highway, your engine should be charging your battery bank.

 

[blars]

Driving with a wind generator on the roof is much less efficent than using an alternator.&nbsp; Wind generators work better when they are high, most are tower mounted.&nbsp; Pondputz put his up the last two winter RTRs.

 

[cedric]

I was told by an electrical engineer guy that an alternator isn't designed to charge house batteries.

 

[wrcsixeight]

Most Automotive charging systems are designed to keep nearly fully charged battery, fully charged.<br /><br />When deep cycle batteries are added, then the weakness of the originally designed system become obvious and the house batteries suffer chronic undercharging sulfation and premature death.<br /><br />Alternators can do an ok to good job bringing house batteries up to 80% if the charging circuit is upgraded with thicker cabling, after that it might take several hours more of driving.<br /><br />Alternator can produce tremendous heat when they are asked to produce a lot of amperage that depleted house batteries can ask for, through adequate cabling. &nbsp;Cold air feed tubes to the alternator can increase alternator amperage slightly and longevity greatly.<br /><br />Alternators are limited by the vehicle's or it's own voltage regulator. &nbsp;Once the voltage setpoint is reached, the alternator produces only enough juice to hold this voltage, so a 140 amp alternator might only need to produce 15 amps over what the engine management system requires to hold 14.4, or 13.7 volts or whatever number the engineers decided was adequate to minimize the chance of overcharging a battery.<br /><br />Grid powered wall chargers can basically hold 14.5 volts and squeeze in more amps.<br /><br />I have seen as little as 7 amps from my alternator when my batteries were at 65% and 14.5 volts. &nbsp;Then shutting off the engine, my solar took back over and was sending 11.5 amps into the house batteries.<br /><br />Getting batteries from 80 to 100% can take 4 times longer than it took to get them from 40 to 80 percent. &nbsp;It is just the nature of lead acid battery charging, and alternators do very poorly in this upper range.<br /><br />A properly designed wind generator on the roof could potentially do a better job than an alternator, at a huge price point that would never get past any bean counter.<br /><br /><br />

 

[Les H]

my understanding of this is that you would be better off using the wind turbine while stopped. The adfed drag of the turbine on the roof while moving will cause the engine to work harder, thus using more gas. im sure that there is a scientific equasion somewhere that will convert horsepower and fuel used into kilowatts, and the kilowatts oroduced by the turbine and the point where you use more power than you produce. Very similar to the perpetual motion machine, there is no "free" enefgy.

 

[Ricekila]

And there is something about spinning things that the law don't care for <img src="/images/boards/smilies/rolleyes.gif" alt="" align="absMiddle" border="0" />

 

[josephusminimus]

Hey<br />I was wondering if they make/sell wind generators that mount on your van roof. Could you charge your batteries while driving?? seems to me there is a lot of wind up on my roof at 65mph

<br /><br />The original question of whether they make or sell generators for this purpose or designed to be used in this way is almost certainly a simple 'no'.&nbsp; Designs and manufacturing of products need a consumer base widespread enough to create a demand for the product.<br /><br />But if you have a reason for doing it to solve your own unique needs it wouldn't be too difficult to put together a ram-air wind tunnel turbine that would do the job, wouldn't be particularly obvious or costly.<br /><br />But you'd pay a price in drag on the vehicle, possibly noise and vibration, possibly in other ways.&nbsp; One of the biggest problems with wind generators has always been the wear and tear on the mechanical side of things because of high rpms.&nbsp; During the past couple of decades a lot of designs have been showing up for low-rpm generators with feathering vanes and a lot of gearing down to compensate for the change in rpms of the vanes.&nbsp; But the only place I can think of a person might mount something of this sort would be on the front of the vehicle.<br /><br />There's also the matter of the dirt and gunk the surfaces would inevitably pick up off the road to penetrate wear surfaces and reduce the efficiency of the vanes.<br /><br />There's a place in this world for wind generators, particular the low-rpm ones, but probably this isn't it.&nbsp; Fun thing to think about, though.

 

[joey]

Why not install an extra bracket and high amp alternator totally dedicated to the house batteries?

 

[Seraphim]

It's been done, Joey.&nbsp; Our diesel came with a snow plow package that included a second higher amp alternator.&nbsp; Thought about dedicating it to the house battery, since I don't plow, but haven't needed to. The alternators in tandem charge all three batteries just fine.&nbsp; I do have to remeber to unplug the house from the truck on overnighters - there's no isolator and I don't want to drain the truck's batteries (not much of a chance, but still...)

 

[cedric]

thanks for all the good responses folks. I was just really curious and thought it might be a good idea. I learned a lot. thanks again

 

[highdesertranger]

remember the laws of physics.&nbsp; there are always loses you can never produce more power than you use to produce that power.&nbsp; so you will lose more in mpg than the power produced.&nbsp; remeber this is law, not speculation.&nbsp; like allot of what they call science nowadays.&nbsp; highdesertranger