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Thread: Charger and DC-DC problems

              
   
   
  1. #1
    Senior Member Coninsan's Avatar
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    Charger and DC-DC problems

    Hello all

    I'm just about at that point where I'm starting to think about my bikes wiring, 12 Volt system, connecting the BMS, contactor and such. You know the drill.

    But I have run into a slight problem.
    I have the DeltaQ QuiQ-dci unit, the QuiQ charger with a DC-DC unit built in. The Charger and DC-DC share the +/- cables running to the battery pack.
    It just occured to me that those +/- cords have to run through the BMS which probably doesn't support the current running back to the DC-DC unit in which case I would have no power for my 12 Volt system.
    But running a direct line from the pack to the DC-DC unit would override the BMS and potentially fry my battery pack during charging..

    How do I run power to the DC-DC unit without frying my batterypack?
    "I reject your reality and substitute my own." Adam Savage

  2. #2
    Not to be taken seriously DaveAK's Avatar
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    What BMS are you using? If it requires pack voltage you should be able to run separate leads to it from the battery pack, i.e. in parallel to the DC-DC connections, not in series with them. Please someone confirm this!

  3. #3
    Senior Member Coninsan's Avatar
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    I'm using the Fetcher Goodrum BMS. Which is placed on the minus connection between the Charger and Battery pack.
    The problem lies in that the Charger and DC-DC shares the same connection to the Battery pack. Which is hard wired inside the Quiq-dci unit.

    I am thinking that the only way could be to have a switch to switch the bike between "driving mode" and "charging mode" Either providing a connection to the DC-DC unit or the BMS, but there would have to be a failsafe that wouldn't let the bike run when the bike is in "chargin mode"
    And is there even a switch available that can take the current?
    Last edited by Coninsan; 14 February 2011 at 1429.
    "I reject your reality and substitute my own." Adam Savage

  4. #4
    Not to be taken seriously DaveAK's Avatar
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    I think that BMS can take a reasonable amount of amps. Can't remember the exact figure. So how many amps does the charger put out, and how many does the DC-DC converter draw? And what is the maximum the BMS can handle?

  5. #5
    Senior Member Coninsan's Avatar
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    The charger outputs a maximum of 12 amps. and the DC-DC would draw a maximum of 5 amps I reckon, based on that it is a 400 watt unit. A quick search shows that the BMS can handle 20 amps of charge current.

    But do you think that the BMS would even let the current flow through the BMS to the DC-DC unit?
    Last edited by Coninsan; 14 February 2011 at 1455.
    "I reject your reality and substitute my own." Adam Savage

  6. #6
    Not to be taken seriously DaveAK's Avatar
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    Quote Originally Posted by Coninsan View Post
    The charger outputs a maximum of 12 amps. and the DC-DC would draw a maximum of 5 amps I reckon, based on that it is a 400 watt unit.
    But do you think that the BMS would even let the current flow to the DC-DC unit?
    I'd hate to go through that monster thread over on ES again, but I seem to recall it will handle at least 15amps. That's what you need to get confirmation on I think. It's been a long time since I followed their progress, so I'm not even sure how it's supposed to hook up and operate. Try looking through that thread again and if you can't find the information then PM fecther. Explain that you've got to feed the DC-DC as well. I think your biggest problem is that if the BMS switches the incoming charger wire, then obviously it will be switching the DC-DC supply as well. You might need to add a lead which you can switch between charging and riding so that you can bypass the charger cutoff and feed the DC-DC.

    This is just all guess work and throwing ideas out there. Without knowing enough about the BMS and how it's supposed to be hooked up it's difficult to give a definitive answer. I'm sure there's a good solution to be had though.

  7. #7
    Senior Member Coninsan's Avatar
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    Thanks for your thoughts DavAK

    The simplest solution I can think off, is this: Two female connectors, one male. To work as a switch between driving mode and charging mode.
    But how to prevent the bike from charging while in driving mode?
    "I reject your reality and substitute my own." Adam Savage

  8. #8
    Empulse R #24 frodus's Avatar
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    I asked Fechter (a friend of mine on ES). Between that and being familiar with the DeltaQ, we'll get you sorted

    stay tuned ok?

    I don't think the fechter goodrum BMS needs to cutoff the charger, it just needs to signal to it to stop charging. The deltaQ has a low voltage input wire for that (white) when lithium is used.
    Travis

  9. #9
    Empulse R #24 frodus's Avatar
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    do you have a schematic? can you send it to me?
    Travis

  10. #10
    Senior Member Coninsan's Avatar
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    I don't have a schematic for my bike, havn't got 'round to that yet. This problem just occured to me.
    "I reject your reality and substitute my own." Adam Savage

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