Captain Hybrid

Slideshow: Fuel-Stingy Technologies Set Sights on 54.5 MPG

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William K.
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Re: Fuel economy, 36 volt systems?
William K.   10/10/2013 3:09:22 PM
In reality a higher battery voltage will mean a larger alternator and a greater alternator load. The reason for the higher voltage is to provide enough electrical power for all of the loads. The higher voltage was never to reduce the weight of the wires. The first suggestion s for the 36 volt system, (42 volts) was to power the electrically heated catalytic converter. The concept was to delay the start while bringing the catalyst up to operating temperature using electrical heat.  The power consumed was about the same as for cranking the engine for several minutes. The good news is that the idea was so very stupid that it was never released. What could be useful for the stop-start driving method would be a 24 volt alternator/starter unit, such as the Continental one pictured in the slideshow.

What stands in the way of the effective impplementation of the ultimate stop-start system is engine driven power steering, and air conditioning demands. Right now, I can shift my car into neutral and coast to a light, but it will not drop below 1500RPM until the vehicle is stopped. That is to assure power steering bost while still moving.

With most cars now being much lighter than when power steering first became popular, it seems that we should go back to the non-powered type of steering systems. They were not that hard to turn, and they were both less expensive and more reliable. And if we got rid of some drivers, so much the better. Fewer drivers, les crowded roads.

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Aluminum wiring-bad idea!
armorris   1/9/2014 9:59:35 AM
Referring to slide #7, aluminum wiring. That's a very bad idea. While aluminum may be lighter than copper, aluminum oxidizes far more easily than copper, causing faulty electrical connections. It was used in houses for a while, but caused many fires and has since been discontinued. Now add to that, the temperature and humidity of an automotive application, I predict that the reliability will be extremely low. Bad idea!

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36 or 42 volt battery voltage
armorris   1/9/2014 11:03:17 AM
A big problem with a high battery voltage like 36 or 42 volts is that the various incandescent lamps in the vehicle will have longer, thinner, more fragile filaments. This would greatly reduce their reliability. While everything is moving toward LEDs, switch-mode power converters will be needed to adapt LEDs to such a high voltage. This would cause weight, cost and reliability issues. Of course, even at 12 volts, higher powered LEDs would require switch-mode power converters to avoid energy loss. The size and cost of the components in a switch-mode power converter are affected by the wattage, not the battery voltage.

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Re: Fuel economy, 36 volt systems?
armorris   1/9/2014 12:17:52 PM
The military uses 28 volts on aircraft. I know because I spent most of my career designing automatic test tquipment for aircraft and missile electronics. I imagine the military uses 24 volts in vehicles. I have no experience with that.

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