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Thread: Should the futura keep runnign if you disconnect the battery?

  1. #1
    apriliaforum Member
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    Should the futura keep runnign if you disconnect the battery?

    morning all ..

    i was tidying up some of the wiring on my bike last night and i discovered something that i don't understand.


    I decided to reroute the cable i added to the negative battery terminal as part of the charging system modification so i unscrewed the negative terminal and pulled back the cables.

    Now here's the puzzeling bit for me. While I did this the engine was running and i fully expected it to keep running even with no battery connected. My understanding is that the battery would not be needed once the engine was started as all power requirements would be provided from the rectifier.

    But .... the engine cut out immediately.

    My voltage readings at the battery during idle is 13.96V and drops to about 13.5V over the majority of the rev range. I've assumed this indicate the charging system is ok and should provide enough current to run the bike . .but is that assumption a good one? Or, is it normal for the engine to cut out if you disconnect the battery?

    I would love to hear your thoughts on this.

    Dave.

  2. #2
    apriliaforum expert deefred's Avatar
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    I´m no expert, but you have created an open circuit by removing the battery and the bike should per design die.

    If you would connect the battery cables together the bike may continue to run but I would not do that.

    This is only a guess.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch. EBC 320mm brake discs
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  3. #3
    apriliaforum expert 01Futuraman's Avatar
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    don't think it is advisable to work on the battery or anything electric while the bike is running, would figure it could give you a good jolt
    Mods:rectifier replacement, soldered wires, derestricted airbox, QDC replacement with metal one, capped holes on fuel plate, basically just the standard stuff we have to do to be safe and keep them running well
    Road: 01 Aprilia Futura
    Track: 05 Triumph Daytona 650
    Dirt: 06 Honda CRF230F

  4. #4
    apriliaforum expert RobC's Avatar
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    at a guess, disconnecting the battery might cause the regulator output to become unstable - the battery acts like a huge capacitor. The ECU wouldn't be happy and assume there is a fault, shutting down the bike. Check your error codes, might be something registered there.
    I know we used to run alternator systems without a battery before the days of electronic ignition, but we would put a large capacitor in place of the battery to stop voltage spikes.

    Deefred, if you short he battery connectors, wouldn't that stand a good chance of blowing the regulator, or at least the main fuses?

    Futuraman, you shouldn't get a jolt from the battery circuit, it's only 12v after all! Messing with the coils on a running bike is another matter with 30kv+ floating around the ht leads. That might make your fingers tingle.

  5. #5
    apriliaforum expert deefred's Avatar
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    Quote Originally Posted by RobC View Post

    Deefred, if you short he battery connectors, wouldn't that stand a good chance of blowing the regulator, or at least the main fuses?
    I don´t know what would happen and I have no intentions to find out either (at least not on my own bike)
    Last edited by deefred; 02-27-2009 at 11:13 AM.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch. EBC 320mm brake discs
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  6. #6
    apriliaforum expert RAS's Avatar
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    I seem to remember the coils being controlled by the ECU on the ground side.

    Disconnect the earth ground to your houses' wiring and see if anythng comes on

    Now, I think that it's possible, because of where the reg feeds in to the wiring, that it might "run" with the pos side disconnected.

  7. #7
    apriliaforum expert deefred's Avatar
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    Quote Originally Posted by daveBiffo View Post

    My voltage readings at the battery during idle is 13.96V and drops to about 13.5V over the majority of the rev range. I've assumed this indicate the charging system is ok and should provide enough current to run the bike . .but is that assumption a good one? Or, is it normal for the engine to cut out if you disconnect the battery?

    I would love to hear your thoughts on this.

    Dave.
    Your values seem low.

    @ 4000 rpm light ON, I went from 13.34 to 14.09 after mod.

    Did you add wires also to the positive side?
    I added wires for both negative and positive.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch. EBC 320mm brake discs
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  8. #8
    apriliaforum expert Dan's Avatar
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    The magnets in the stator require current to make current, so if the source of current is removed.... everything goes dead.

    When the bike does not run right or suddenly develops strange behavior (fans not coming on, misfire, turn signals acting up, etc.), the first thing to do is check the condition of the battery. Second thing to do is check the charging rate applied to the battery.
    If I just gave you mechanical, personal, legal or medical advice, it's up to you to get a proper diagnosis from a qualified expert.

  9. #9
    apriliaforum expert deefred's Avatar
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    Quote Originally Posted by Dan View Post
    The magnets in the stator require current to make current, so if the source of current is removed.... everything goes dead.
    Sorry but this is not correct.
    That´s the beauty of using magnets instead of creating a magnetic field using a coil and current.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch. EBC 320mm brake discs
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  10. #10
    apriliaforum expert RAS's Avatar
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    Quote Originally Posted by deefred View Post
    Sorry but this is not correct.
    That´s the beauty of using magnets instead of creating a magnetic field using a coil and current.
    of course the flip side is a regulator that has to bleed off all that excess voltage as heat.

    Dan, think of your basic chainsaw/weedwacker/whatever. The magneto manages to power a sparkplug w/o any battery.

  11. #11
    apriliaforum expert kzmille's Avatar
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    Back in the days of DC generators on cars with mechanical voltage regulators a simple test to see if the charging system was working was to disconnect the battery. If the engine died you knew there was very little charging output. Although you could get away with that on older cars it is very risky on modern fuel injected computer controlled vehicles.

    There should be a sticker like this near the battery on your bike.
    Attached Images Attached Images  

  12. #12
    apriliaforum expert deefred's Avatar
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    Never seen that sticker before.

    Which Aprilias use a normal lead acid battery?

    P.S I should know better my RS 250 has one, but haven´t seen the sticker.
    Last edited by deefred; 02-27-2009 at 10:29 AM.
    2001 RST Futura in stream Silver.
    Mods: Modified Öhlins fork from mille R, EBC brake discs, HEL front brakelines, Carbon RS 250 front fender, Wiring mod for charging. Engine related:05 map, Iridium plugs, tuneboy, derestriced intake, old mille airboot, staintunes exhaust. Lambda bung hardbrazed in the "breadbox". Öhlins mille R rear shock with 110N/mm spring and the integrated hydraulic preload adjuster. LED Voltmeter installed inside the dash for monitoring charging. Duc 999 radial m/c for brake and clutch. EBC 320mm brake discs
    NWS hugger. Equipment: Famsa tankbag,
    CBR 600 -07 MOSFET R&R FH008EE providing stable 14.4 - 14.5 V (with my wiring mod). Daytona heated grips with mccoi pwm controller and automatic chain oiler

  13. #13
    apriliaforum expert Dan's Avatar
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    Quote Originally Posted by deefred View Post
    Sorry but this is not correct.
    That´s the beauty of using magnets instead of creating a magnetic field using a coil and current.
    Ok, I wuz thinkin' alternators.
    If I just gave you mechanical, personal, legal or medical advice, it's up to you to get a proper diagnosis from a qualified expert.

  14. #14
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    guys,

    thanks a lot for the replies. In the back of my mind i thought this signified some problem with my charging system but its good to know that it's expected behaviour.

    I've also been educated that its bad to disconnect while the bike is running so i'll not be doing that again.

  15. #15
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    Quote Originally Posted by deefred View Post
    Your values seem low.

    @ 4000 rpm light ON, I went from 13.34 to 14.09 after mod.

    Did you add wires also to the positive side?
    I added wires for both negative and positive.

    yeah, i added both wires, negative to battery negative terminal and positive to the bottom of the fuse box.
    I read 14V at idle but 13.5V at 4k rpm (dip beam on).

    is the 4000 rpm reading too low?

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