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Thread: Dealing With How To Turn on Your Bike

              
   
   
  1. #1
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    Dealing With How To Turn on Your Bike

    Trying to figure out the best way to turn on the motorcycle:

    Here's the problem:
    So You have a big battery pack and a DC-DC step down converter. In order to turn on the DC-DC step down you need to turn on the high voltage system, but turning on the high voltage system requires a low voltage system to trip a relay.

    Here's the solution?
    1. Use an auxiliary 12V battery to control the 12 volt relays and power the necessary systems before the Highvoltage/DC-DC are active.

    2. Connect a portion of the main battery pack to the DC-DC via a mechanical switch. This requires additional contractors in order to properly control connection between battery packs and systems.


    So my question is, what did you guys do?

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    Senior Member Hugues's Avatar
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    My 12 volts DC-DC is always on, my BMS needs it, and some other stuff. But maybe this is not you're asking.
    Regards from Switzerland
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    Quote Originally Posted by Hugues View Post
    My 12 volts DC-DC is always on, my BMS needs it, and some other stuff. But maybe this is not you're asking.
    So in normal use, assuming you were going to ride or charge it that would be fine. But if you need to store it, what do you do?

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    Empulse R #24 frodus's Avatar
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    Or get a dc-dc with a built in enable/disable, or something like a sure power that has an always on and a keyed on. They're good up to 96v packs and are 400w.

    I can get them if needed.

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    Senior Member __Tango's Avatar
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    My DC-DC is connected almost all of the time. The circuit that runs from the B+ to the DC-DC +In runs through an anderson connector that's accessible on the side of the bike. So whenever I want to do long term storage, I just disconnect that one connection. I wanted a switch of some sort, but finding a 120V DC switch was hard, and anyway a simple connection was the least hassle.
    EVs: 2007 Zapino Scooter, Honda VF500 Conversion (electriceptor.wordpress.com), Red Nissan LEAF SL (Arrived!)

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    Senior Member Stevo's Avatar
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    x2 for the Anderson connectors.
    I'm also going to try one of these: 400A Emergency EV Disconnect Switch
    It's quite robust and should work fine for my app. I wouldn't use one for anything over 90 volts pulling more than 400 amps (stated good for 1000 volts however)
    Last edited by Stevo; 03 February 2015 at 1908.
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
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    Quote Originally Posted by frodus View Post
    Or get a dc-dc with a built in enable/disable, or something like a sure power that has an always on and a keyed on. They're good up to 96v packs and are 400w.

    I can get them if needed.
    So correct me if I'm misunderstanding you, but don't you need the contractor to close in order to power the DC-DC?

    What is this sure power? I found an all in one battery jumper that I was thinking would be easy to use as 12 volt auxiliary power: Amazon.com: PowerAll PBJS12000R Rosso Red/Black Portable Power Bank and Car Jump Starter: Automotive

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    Quote Originally Posted by __Tango View Post
    My DC-DC is connected almost all of the time. The circuit that runs from the B+ to the DC-DC +In runs through an anderson connector that's accessible on the side of the bike. So whenever I want to do long term storage, I just disconnect that one connection. I wanted a switch of some sort, but finding a 120V DC switch was hard, and anyway a simple connection was the least hassle.
    I didn't think about how slowly it would drain just in standby. I will look into this option.

    What is your option about the post above this one? its an all in one 12V car jumper. so the idea would be charge it up from the battery pack while the bike is charging, then use it to start the bike. I think really the only advantage of this system over yours is being able to just use a 12volt switch to start the bike and also to be able to power/test the low voltage system without engaging high voltage.

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    Empulse R #24 frodus's Avatar
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    Quote Originally Posted by theFREElaker View Post
    So correct me if I'm misunderstanding you, but don't you need the contractor to close in order to power the DC-DC?

    What is this sure power? I found an all in one battery jumper that I was thinking would be easy to use as 12 volt auxiliary power: Amazon.com: PowerAll PBJS12000R Rosso Red/Black Portable Power Bank and Car Jump Starter: Automotive
    No.... The contactor is for the controller.

    You would have a dc-dc that is connected direct to the pack via a fuse of course. You can get one that allows you to enable and disable it so it's not on all the time.

    Surepower is a company that makes a 71030i that has an always on output (for things like bms that always need power) and a switched output for the rest of the 12v system. You would just use a normal switch like the key to turn the dc-dc on, then have the switched 12v close a relay that would turn your controller on.

    Sure Power 71030i DC-DC Converter 72/96V to 13.5V, 30A 400W (fits GEM Cars) - DC-DC CONVERTERS - EV PARTS

    I can get them for much cheaper if you need one.

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    Quote Originally Posted by frodus View Post
    No.... The contactor is for the controller.

    You would have a dc-dc that is connected direct to the pack via a fuse of course. You can get one that allows you to enable and disable it so it's not on all the time.

    Surepower is a company that makes a 71030i that has an always on output (for things like bms that always need power) and a switched output for the rest of the 12v system. You would just use a normal switch like the key to turn the dc-dc on, then have the switched 12v close a relay that would turn your controller on.

    Sure Power 71030i DC-DC Converter 72/96V to 13.5V, 30A 400W (fits GEM Cars) - DC-DC CONVERTERS - EV PARTS

    I can get them for much cheaper if you need one.

    duh my bad, wasn't thinking on the contractor

    Didn't even think to check if the Dc-Dc converters have an on/off switch. It looks like that particular model has an input voltage range that is too low for my battery pack. My pack will see a voltage swing from 110Volts to 156Volts. Do you have anything along those lines?

    Also, I haven't calculated out yet, but what is the typical power demand for the low voltage system, just off the top of your head?

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