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03-30-2010, 09:26 AM
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#1
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3 Rivet Member
1964 26' Overlander
Gloucester
, Virginia
Join Date: Mar 2010
Posts: 167
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Crazy Idea
Has anybody considered putting regenerative brakes on an AS? Last year GMC released the Sierra truck as a hybrid. The brakes for that vehicle might be able to fit an Airstream. I just think it might be interesting to charge your batteries every time you tap the brakes.
If I am just completely off my nut for thinking about this let me know.
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03-30-2010, 09:41 AM
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#2
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banjobill
2000 30' Limited
battle ground,
, Washington
Join Date: Jun 2009
Posts: 516
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disc brakes are (were) on the horizon
Wow, that's a great idea! I was thinking about putting disc brakes on the AS instead of rebuilding-now I am thinking regen brakes, 'course the cost will probably kill the idea.
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03-30-2010, 10:09 AM
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#3
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Rivet Master
1984 31' Excella
Broken Arrow
, Oklahoma
Join Date: Jan 2005
Posts: 673
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Brakes
Ok so take it one more step.
If you pur regenerative brakes on the AS, why cant you also use them as dynamic brakes as on a Diesel Locomotive?
Beginner
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03-30-2010, 11:23 AM
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#4
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Rivet Master
1972 31' Sovereign
Lexington
, Minnesota
Join Date: Feb 2009
Posts: 3,991
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Quote:
Originally Posted by Beginner
If you pur regenerative brakes on the AS, why cant you also use them as dynamic brakes as on a Diesel Locomotive?
Beginner
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Regenerative brakes and Dynamic brakes rely on some of the same basic principles, where they will use the resistance of a “generator” to provide braking force instead of the friction of brake pads and shoes. What you do with the electricity generated by the braking force is where they are different. Regenerative brakes on a hybrid or electric car use that electricity to recharge the batteries. Dynamic brakes on the other hand, simply dump that electricity into honking big resistors to slow the train. They produce a fair amount of waste heat, but do not wear out like a friction pad would. Not used to recharge batteries much if at all. There are a few more significant differences, but those are the basic principles.
Chris
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03-30-2010, 11:32 AM
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#5
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3 Rivet Member
1964 26' Overlander
Gloucester
, Virginia
Join Date: Mar 2010
Posts: 167
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Wow..so the idea has some merit. I thought you all were gonna run me off as a crazy. I wonder how you go about obtaining regen breaks.
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03-30-2010, 11:37 AM
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#6
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Rivet Master
1972 31' Sovereign
Lexington
, Minnesota
Join Date: Feb 2009
Posts: 3,991
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Oh, every idea has merit! It's just a question of how much money you'll want to throw at it, let alone finding the parts to do it.
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03-30-2010, 11:40 AM
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#7
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3 Rivet Member
1964 26' Overlander
Gloucester
, Virginia
Join Date: Mar 2010
Posts: 167
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You're right Chris that's the hard part. At least hard for now but I suspect as hybrids become increasingly popular and mainstream that parts will get cheaper and more abundant.
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03-30-2010, 12:08 PM
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#8
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Rivet Master
1997 34' Limited
1970 27' Overlander
South of Atlanta
, Georgia
Join Date: Sep 2009
Posts: 1,709
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Start looking for wrecked Sierra's.
__________________
Craig and Carol
1997 34' Excella 1000
1970 27' Overlander, International
2009 Ford F150 5.4L
ProPride hitch with 1400# bars
AIR 41028
TAC GA-8
WBCCI 10199
Past President Southeastern Camping Unit (12)
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03-30-2010, 01:25 PM
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#9
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3 Rivet Member
1994 21' Sovereign
Tucson
, Arizona
Join Date: Mar 2006
Posts: 175
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It's not the brakes that do the regeneration, it's the drive train and electric motor, which also acts as a generator.
Of course the vehicle needs to have conventional brakes too, since more braking can be needed then the regenerative process will produce.
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03-30-2010, 01:41 PM
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#10
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Rivet Master
1984 31' Excella
Broken Arrow
, Oklahoma
Join Date: Jan 2005
Posts: 673
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Regenerative Brakes
I was unsure if the electricity produced was "burned off" by resistors or if reverse polarity Electricity was gradually fed to the drive/generator motor trying to reverse it.
However I'm not really sure if regenerative braking would be really pratical on a car as at some point you would be producing to much energy (voltage level goes to high for batteries) or heat becomes too great for the motor.
The long pole in the tent though is money.
Beginner
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03-30-2010, 01:53 PM
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#11
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Rivet Master
, Minnesota
Join Date: Aug 2003
Posts: 7,721
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I think the more practical problem with diesel locomotives is economics. You would need a really big honking set of batteries to store all that energy that is now being thrown off in the resistors. And they would really only be useful on those long downhill runs out west. Otherwise they are like regenerative brakes on a car - pretty useless when you're cruising the interstate, only useful in stop and go city traffic.
Same reason they work so well on city buses, not so good on interstate trucks.
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03-30-2010, 02:05 PM
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#12
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Wise Elder
2010 30' Classic
Vintage Kin Owner
South of the river
, Minnesota
Join Date: Dec 2009
Posts: 4,169
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Quote:
Originally Posted by JFerguson
Has anybody considered putting regenerative brakes on an AS? Last year GMC released the Sierra truck as a hybrid. The brakes for that vehicle might be able to fit an Airstream. I just think it might be interesting to charge your batteries every time you tap the brakes.
If I am just completely off my nut for thinking about this let me know.
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The Sierra regenerative braking works using a motor-generator between the engine and the transmission.
It would work fine on an Airstream if you're willing to retrofit a suitable drive train less engine. For braking on both axles you'd want a twin screw setup, and a 4L60e transmission out of the Sierra, and the motor-generator. Then it's simply a matter of some controls and programming.
In general, traction motors are too heavy to be placed on the axle except for rail applications because the unsprung weight goes way too high, so the obvious solution of a planetary gear unit and a motor/generator on the axle won't work. That leaves the standard possibilities of either a solid axle (cheap but heavy) or a full-floating setup with independent shafts to a center diff or maybe to a planetary and m-g dedicated to each wheel.
As late as the 1990s some German passenger railcars used a generator driven by one wheel to charge batteries. The rest of the world uses head-end power (HEP), but the advantage of the old German system was that no electrical connection was required between cars.
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03-30-2010, 02:10 PM
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#13
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Usually Sleepy
1973 27' Overlander
East Haven
, Connecticut
Join Date: Aug 2007
Posts: 1,155
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Quote:
Originally Posted by snake
It's not the brakes that do the regeneration, it's the drive train and electric motor, which also acts as a generator.
Of course the vehicle needs to have conventional brakes too, since more braking can be needed then the regenerative process will produce.
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exactly! Then the issue becomes:
How does one connect all 4 wheels to some sort of generator. I'm not saying it's impossible, just an issue.
__________________
Skip
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03-30-2010, 02:42 PM
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#14
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3 Rivet Member
1964 26' Overlander
Gloucester
, Virginia
Join Date: Mar 2010
Posts: 167
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Quote:
Originally Posted by snake
It's not the brakes that do the regeneration, it's the drive train and electric motor, which also acts as a generator.
Of course the vehicle needs to have conventional brakes too, since more braking can be needed then the regenerative process will produce.
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A good friend pointed that same point out to me. Ah well, at least I got folks thinking.
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03-30-2010, 02:56 PM
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#15
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Rivet Master
1997 34' Limited
1970 27' Overlander
South of Atlanta
, Georgia
Join Date: Sep 2009
Posts: 1,709
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I don't even want to think about trying this with 3 axles. That would be three wrecks, three sets of axles, a new suspension system since the torsion type from the factory wont work with a split axle......., but it is a great idea. I am glad you got me thinking.
__________________
Craig and Carol
1997 34' Excella 1000
1970 27' Overlander, International
2009 Ford F150 5.4L
ProPride hitch with 1400# bars
AIR 41028
TAC GA-8
WBCCI 10199
Past President Southeastern Camping Unit (12)
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03-30-2010, 02:59 PM
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#16
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3 Rivet Member
1964 26' Overlander
Gloucester
, Virginia
Join Date: Mar 2010
Posts: 167
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Quote:
Originally Posted by Jammer
The Sierra regenerative braking works using a motor-generator between the engine and the transmission.
It would work fine on an Airstream if you're willing to retrofit a suitable drive train less engine. For braking on both axles you'd want a twin screw setup, and a 4L60e transmission out of the Sierra, and the motor-generator. Then it's simply a matter of some controls and programming.
In general, traction motors are too heavy to be placed on the axle except for rail applications because the unsprung weight goes way too high, so the obvious solution of a planetary gear unit and a motor/generator on the axle won't work. That leaves the standard possibilities of either a solid axle (cheap but heavy) or a full-floating setup with independent shafts to a center diff or maybe to a planetary and m-g dedicated to each wheel.
As late as the 1990s some German passenger railcars used a generator driven by one wheel to charge batteries. The rest of the world uses head-end power (HEP), but the advantage of the old German system was that no electrical connection was required between cars.
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You can actually take this concept one step further and have a trailer that could actually propel itself, like supplemental power on a hill or getting unstuck out in the boondocks. I was kind of inspired by what this guy did:
Electric Porsche 944
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03-30-2010, 03:03 PM
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#17
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3 Rivet Member
1964 26' Overlander
Gloucester
, Virginia
Join Date: Mar 2010
Posts: 167
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Quote:
Originally Posted by Aviator
I don't even want to think about trying this with 3 axles. That would be three wrecks, three sets of axles, a new suspension system since the torsion type from the factory wont work with a split axle......., but it is a great idea. I am glad you got me thinking.
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Oh I agree this is pandora's box! I dont' even want to think about what a modification like this would do to resale value.
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03-30-2010, 03:07 PM
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#18
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Maniacal Engineer
1971 25' Tradewind
Lopez Island
, Washington
Join Date: Jan 2010
Posts: 1,244
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Interesting idea, but this is really better implemented on the tow vehicle. That way, one can descend hills using regenerative braking much as one uses compression brakes, and the trailer service brakes are left unmodified to deal with more emergency stopping conditions. Keep in mind that whatever energy storage mechanism is employed, it needs to deal with storing the power generated by retarding speed on long downgrades; for 14k lbs or more for trailer + TV this can easily be 100 to 200 KW - not something you're going to easily store quickly - that's 300 to 600 amps at 330 volts - an impressive battery charger indeed.
I built a hydraulic hybrid car as part of a master's thesis in mechanical engineering in the early 80s; I ended up using a hydraulic accumulator & pump/motor as it would store & discharge power at a much higher rate than an equivalent weight of lead acid batteries.
Storing all the available energy on a long descent is hard.
- Bart
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03-30-2010, 03:14 PM
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#19
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3 Rivet Member
1964 26' Overlander
Gloucester
, Virginia
Join Date: Mar 2010
Posts: 167
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Quote:
Originally Posted by barts
I built a hydraulic hybrid car as part of a master's thesis in mechanical engineering in the early 80s; I ended up using a hydraulic accumulator & pump/motor as it would store & discharge power at a much higher rate than an equivalent weight of lead acid batteries.
Storing all the available energy on a long descent is hard.
- Bart
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Wow!!! That is so cool. Do you have any pictures?
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03-30-2010, 08:30 PM
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#20
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Rivet Master
2020 30' Classic
Derwood
, Maryland
Join Date: Mar 2010
Posts: 1,515
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Quote:
Originally Posted by barts
I built a hydraulic hybrid car as part of a master's thesis in mechanical engineering in the early 80s; I ended up using a hydraulic accumulator & pump/motor as it would store & discharge power at a much higher rate than an equivalent weight of lead acid batteries. - Bart
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Kinda like the "air-accumulator" used by the Indians in Asia...
__________________
John "JFScheck" Scheck
2020 30’ Airstream Classic
**I Love U.S.A.**
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