Posted: 7/31/2015 12:10:33 PM EDT
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I read most of the links.
Why would you want to do this -i.e., what's your application? No, I haven't remoted the 3 phase output of an inverter to an external rectifier, altho I can see some potential reasons why it might be a good idea, such as battery charging... I have remoted the sensing of a Leece Neville alternator to a bank of solar system batteries so as to provide ~100 amps at full charging voltage -that I can adjust... Here |
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The largest disadvantage of taking DC directly off the standard in-vehicle alternator/battery is the degradation of the DC output (volts and amps) as the alternator heats up and wire losses. By tapping into the stator wires and remoting some/all the rectifiers give two large advantages, IMO:
1.Heat is reduced per unit of output at the alternator. Therefore, the output degrades less. 2.The stators produce AC. Therefore, a 20-60 foot wire run has minimal wire loses with 10 gauge or better compared to DC. Besides wind & hydro energy applications, personal BOV’s, RV’s and tow vehicles would not require a weighty generator and converter/charger or a mass of solar panels plus to be added to the mix. Deep cycle batteries could be easily charged by the vehicles alternator at the cost of .5 - .6 gal per hour of fuel. For AC applications (compressor, tools, etc.), add a low weight 1kw-2kw inverter to the mix. Anderson connectors provide multiple options. As an example: https://www.youtube.com/watch?v=njNYuEKW-ek |
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Quoted:
The largest disadvantage of taking DC directly off the standard in-vehicle alternator/battery is the degradation of the DC output (volts and amps) as the alternator heats up and wire losses. By tapping into the stator wires and remoting some/all the rectifiers give two large advantages, IMO: 1.Heat is reduced per unit of output at the alternator. Therefore, the output degrades less. 2.The stators produce AC. Therefore, a 20-60 foot wire run has minimal wire loses with 10 gauge or better compared to DC. Besides wind & hydro energy applications, personal BOV’s, RV’s and tow vehicles would not require a weighty generator and converter/charger or a mass of solar panels plus to be added to the mix. Deep cycle batteries could be easily charged by the vehicles alternator at the cost of .5 - .6 gal per hour of fuel. For AC applications (compressor, tools, etc.), add a low weight 1kw-2kw inverter to the mix. Anderson connectors provide multiple options. As an example: https://www.youtube.com/watch?v=njNYuEKW-ek "2.The stators produce AC. Therefore, a 20-60 foot wire run has minimal wire loses with 10 gauge or better compared to DC" NO! As others may soon comment, Ohms Law applies equally to AC and DC 
The only advantage is the third conductor sharing the load. |
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It's my understanding that wire losses are related to current and not AC vs. DC or voltage. Power line transmission is done with AC not because AC is inherently more efficient, but because it's easy to use transformers to step AC up from low voltage / high current to high voltage / low current where the transmission losses are greatly reduced. In the RV scenario, you're not transforming the power for lower loss resulting from lower current, you're only moving the point of rectification and maybe helping the alternator run slightly cooler by getting *some* of the heat generated by the rectifier moved away. One of the posters claims 80% less line loss, to which I throw a dumptruck load of bullshit flags. Something else remote rectification could help you accomplish is spreading the alternator's electrical noise all over the place because now it will have long wires to radiate that AC noise like a transmitting antenna. Smarter people may weigh in, but one of the last places I'd seek electrical expertise is an RV forum. |
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Ha! As I was typing "smarter people may weigh in, EXPY37 comes along! The only advantage is the third conductor sharing the load. Nailed it! Well, that and a probably meaningless reduction in alternator heat, but only when there's a heavy load. Edited because Arfcom keeps tossing my quote tags out. Weird. |
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Well, I skimmed through the referenced links and think it is a bad idea.
The short answer is for two reasons: 1. Modern passenger cars and trucks have an alternator which powers the whole vehicle without much headroom. You would have to turn off all electrical loads to safely draw much current from a standard alternator; certainly nowhere near 210 amps. You still cannot draw more amps total from it than the stator can deliver without overheating. 2. The regulator will adjust the output voltage of the alternator based on the factory electrical circuit. The piggy back load you add to the stator windings has no provision for feedback to the regulator, whether it be internal, external or part of the computer. So the result is you get some voltage out of the added on rectifier. Will it be the correct voltage for your secondary circuit? Who knows? The regulator is responding to other demands but does not know about the piggyback circuit demand. You can buy some electronics from a company in the UK which can deal with the problem, but as it stands, this solution is full of bad. If I felt the need to use my 250 HP truck motor to charge my RV batteries, I would invest in a used truck alternator added under the hood next to my OEM alternator. |
| How high amp , The first article referred to 90 amps . Big trucks are not common with 130-150 amp alternators . My experience in trucks has been new Delco-Remy alternator lives a long time., Leece-Neville is crap . You can get new 24si alternators in pad or ear mount and they have built in regulators. They can easily charge over 20 foot run. never tried or found out a max length . I am sure it would just be a cable size increase . |
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Quoted: It used to be a pretty common design on heavy-duty alternators intended for use in utility trucks, ambulances, etc. IIRC, Dimensions Unlimited and Progressive Dynamics both sold a bunch of 'em. Quoted: Quoted: Bottom line; it's a bad idea borne out of ignorance. It used to be a pretty common design on heavy-duty alternators intended for use in utility trucks, ambulances, etc. IIRC, Dimensions Unlimited and Progressive Dynamics both sold a bunch of 'em. I couldn't find anything with my weaksauce Googlefu regarding remote rectification or AC input direct from the alternator for either of the manufacturers you mentioned. Everything I found showed 2-wire DC coming from the alternator. |
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You mean remote rectification? If so, I would be enormously surprised if their thinking was that AC was somehow less lossy than DC given the same V, I and conductor size. But less loss because 3-phase AC needs 2 more conductors than DC? That, I would definitely believe. I couldn't find anything with my weaksauce Googlefu regarding remote rectification or AC input direct from the alternator for either of the manufacturers you mentioned. Everything I found showed 2-wire DC coming from the alternator. Quoted:
Quoted:
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Bottom line; it's a bad idea borne out of ignorance. It used to be a pretty common design on heavy-duty alternators intended for use in utility trucks, ambulances, etc. IIRC, Dimensions Unlimited and Progressive Dynamics both sold a bunch of 'em. I couldn't find anything with my weaksauce Googlefu regarding remote rectification or AC input direct from the alternator for either of the manufacturers you mentioned. Everything I found showed 2-wire DC coming from the alternator. Yep, they've since discontinued those products. I believe the main justification was the ability to use larger, more efficient rectifiers, mounted on larger, more efficient heat sinks, (presumably) mounted in some cooler location. It probably also increased the alternator's "hot" maximum output, by eliminating a significant heat source near the windings. |
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Yep, they've since discontinued those products. I believe the main justification was the ability to use larger, more efficient rectifiers, mounted on larger, more efficient heat sinks, (presumably) mounted in some cooler location. It probably also increased the alternator's "hot" maximum output, by eliminating a significant heat source near the windings. Quoted:
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Bottom line; it's a bad idea borne out of ignorance. It used to be a pretty common design on heavy-duty alternators intended for use in utility trucks, ambulances, etc. IIRC, Dimensions Unlimited and Progressive Dynamics both sold a bunch of 'em. I couldn't find anything with my weaksauce Googlefu regarding remote rectification or AC input direct from the alternator for either of the manufacturers you mentioned. Everything I found showed 2-wire DC coming from the alternator. Yep, they've since discontinued those products. I believe the main justification was the ability to use larger, more efficient rectifiers, mounted on larger, more efficient heat sinks, (presumably) mounted in some cooler location. It probably also increased the alternator's "hot" maximum output, by eliminating a significant heat source near the windings. I think you are correct. Made it much easier to cool the diodes. Things were more 'lossy' in the old days... |
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Use in wind power: http://www.windbluepower.com/External_Rectifier_Connection_Kit_p/er-kit.htm Thermal problem: http://www.electronics-cooling.com/2002/05/thermal-design-challenges-in-automotive-alternator-power-electronics/ A calculator to play with, 16v: http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=2.061&voltage=12&phase=dc&noofconductor=1&distance=60&distanceunit=feet&eres=8&x=42&y=5 "This allows you to extend the distance from the alternator / wind generator to your batteries without suffering the voltage and current loss that affects DC circuits over long cable runs. It also limits the cost of using long expensive #6 gauge cables to reach your batteries, allowing for the use of much cheaper 10-12 AWG 3-conductor extension cords or standard 3-conductor type wire. " Someone needs to set them straight... 
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Its not the standard 16v automotive alternator they are talking about. Check out 1 of theirs, pay attention to the volts vs RPM:
http://www.windbluepower.com/Wind_Blue_Motor_Hydro_Permanent_Magnet_Alternator_p/dc-500.htm Also, simple Ohms law is only close for AC. There are some adjustments needed: http://www.6pie.com/electronic-theory/ohms-law-for-ac-circuits.php You can see the differences if you play with the calculator I posted above. |
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Its not the standard 16v automotive alternator they are talking about. Check out 1 of theirs, pay attention to the volts vs RPM: http://www.windbluepower.com/Wind_Blue_Motor_Hydro_Permanent_Magnet_Alternator_p/dc-500.htm Also, simple Ohms law is only close for AC. There are some adjustments needed: http://www.6pie.com/electronic-theory/ohms-law-for-ac-circuits.php You can see the differences if you play with the calculator I posted above. You have to get well up in frequency for inductance to become a material factor for conductors in air in the context of this topic... Besides, increased inductance [AC resistance] increases the losses. |