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| Disconnecting generator/alternator; How will this improve MPG? | |
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| Tweet Topic Started: Nov 21 2009, 02:25 PM (2,715 Views) | |
| iamgeo | Nov 21 2009, 02:25 PM Post #1 |
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Big League
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Will someone explain in detail how disconnecting the generator(not by removing the belt) will reduce drag/load on the engine and increase MPG?
Edited by iamgeo, Nov 21 2009, 02:27 PM.
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| mwebb | Nov 21 2009, 09:58 PM Post #2 |
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FOG
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it reduces calculated load so Injector Pulse Width can be shorter so less fuel is consumed you can see it connect your scan tool and turn on all the lights and heater blower while watching the calculated load PID how much will be saved ? who knows ? your results may vary and if system voltage drops below 9.6 volts .... maybe a higher number in your car ... things like fuel pump and ECM and IGnition stop working . |
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| Cobb | Nov 21 2009, 10:36 PM Post #3 |
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BANNED
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I had the same idea to use a deep cycle battery and upgrade the heat lights to hid so they do not dim. A guy on another forum I read hooked a solonoid to it and the ac kill switch under hte gas petal, so when he floored it he got an extra 3hp from the alt being disconnected, but his lights dimmed. What mwebb is saying is that the car conserves fuel if it doesnt have the full power it needs electrically. So, its a 2 fold save. 3hp from not having to spend the alt and the engine is further leaned out. Not sure about the geo, but some hondas have a lean burn mode that if entered lets you get extreme fuel economy. |
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| billy508 | Nov 21 2009, 10:52 PM Post #4 |
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billy508
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Be careful Some alts dont like having the load disconnected when they are running. Some times marine systems run into trouble when battery switches are turned to the off position and the engines are running. On The old Chevy one wire alts, you can switch the b+ wire going to the regulator. That way you can forget and run your battery down on a nice rainy night. Low voltage is not your friend. Mweb may correct me if I am wrong but most systems are looking for 13.5 to 13.8 to work correctly
Edited by billy508, Nov 21 2009, 10:55 PM.
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| Metro Fanatic | Dec 27 2009, 07:36 AM Post #5 |
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I'm experimenting with this right now. Check out my personal blog on this site. When I toggle the alternator 'off' (belt still attached)...you can hear the difference in workload on the engine. Right now I'm leaving the altenator on while coasting down hills and flip it off when I'm driving level or climbing. Here's a pic of my mod control panel. (silver switch is alternator disconnect) Batt voltage displayed on bottom right and solar input on top.
Edited by Metro Fanatic, Dec 27 2009, 09:04 PM.
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| rmcelwee | Dec 27 2009, 10:02 AM Post #6 |
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Do our alternators not already "disconnect" when not needed? I thought all modern vehicles did that. If ours do, the savings will be very minimal. I think a rack of batteries charged at home by solar power could give you a small amount of fuel savings but the investment would far outpace the savings. |
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| Woodie | Dec 27 2009, 01:28 PM Post #7 |
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Yes, they do, and we've already had this discussion once. Any savings are going to be miniscule while the chance of screwing up the car are real. |
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| john. | Dec 27 2009, 01:34 PM Post #8 |
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Elite Member
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Altenators output varies by demand. If you turn on wipers,heater, rear defrost, lights the amperage output of the altenator goes up to keep the voltage at around 14v. I agree that running with less than ideal voltage to electrical items is not the way to go. I'm not saying there isn't a gain to be had, but electronics and the battery work and last longest when proper voltges are present. |
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| mwebb | Dec 27 2009, 09:57 PM Post #9 |
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FOG
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...."What mwebb is saying is that the car conserves fuel if it doesn't have the full power it needs electrically. So, its a 2 fold save. 3hp from not having to spend the alt and the engine is further leaned out. ".... .................. no , i am not saying that at all . the system will NOT OPERATE LEAN ever as long as the 02 sensor is still functioning and the system is capable of fuel control i am saying at some point as system voltage falls voltage will drop low enough that the system will stop working ignition will not produce a strong enough spark to to what it has to do... the fuel pump will stop pumping fuel .... the system WILL NOT be running at peak efficiency when operating at voltages lower than it is designed to operate at. how INefficient it will be depends on how low voltage is at the time . ======================================================= having said that some people seem to be getting increased FE values using deep cycle batteries that can hold system voltage ABOVE the minimum needed for length of the trip . while operating with the alternator switched off but they must recharge the batteries often to keep voltage above the minimum . |
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| iamgeo | Dec 27 2009, 10:34 PM Post #10 |
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Big League
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I talked with a well known and trusted auto repair center owner in San Antonio about this subject. The thing that concerned him most was not the improvement in fuel mileage but the effect on the electrical system and computer. Turning the system back on while driving can create an electrical surge that can pretty much wreak havoc with the computer and/or other devices in the car. If you do go this route be sure to keep generator off while driving and turn it back on when car is shut down. |
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| Cobb | Dec 27 2009, 10:35 PM Post #11 |
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BANNED
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Did anyone else read the part about the second meter measuring power from the solar input? |
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| Murf 59 | Dec 28 2009, 01:54 AM Post #12 |
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There's a blog on this site??? I just reread this whole thread, I don't see it |
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| bogs | Dec 28 2009, 12:53 PM Post #13 |
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Duct tape heals all wounds
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If you click on MetroFanatics name, you get some information about that person, including the link to his blog http://geometroforum.com/blog/main/638548/
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| Metro Fanatic | Dec 30 2009, 12:51 PM Post #14 |
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Murph, I must have mistyped. The blog is my personal blog that Bogs is talking about just above. I can't wait to see how/if this impacts FE and overall performance. |
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| Metro Fanatic | Dec 31 2009, 07:28 PM Post #15 |
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Hot off the press. My first fill up since using my newly installed alternator/generator dissable switch set a new MPG record for Bullet. 62.93MPG. I only ran about 80 miles since the installation was complete so I'm hoping to get maybe another 1 or 1.5MPG that this in future tanks. I love this stuff! |
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