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  1. #1
    Senior Member magohn's Avatar
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    Can I use a "Y" adapter cable to charge a MagicShine?

    Hello all,

    Im very happy with my MS MJ808E but the constant connecting/disconnecting of the wring harness to charge seems to be the "weak spot" in the process. As I cycle in cold climates, the connectors are often difficult to pull apart after a longer ride. I was hoping to use a "Y" adapter as sold by Geoman ($7.99) to leave permanently in the circuit. One side would go to my headlight and the other side I would use for charging. Then if the constant connects/disconnects wear the connectors down, it wont matter as its only wearing the "Y" adapter.
    Of course, I would have to waterproof the "open" side of the adapter - thoughts?

    Thanks!

  2. #2
    Senior Member Looigi's Avatar
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    Thoughts: You'll have the headlight connected in parallel with the battery when charging. If the headlight has a mechanical switch and is switched off, it will be fine for charging, but it's tough to know what might happen if the light was switched on while charging without knowing the specifics of the circuitry. If the headlight has an electronic switch, you can't know if it will work for charging without knowing more about that circuit and what the charger outputs and expects to see as a load. I'm sure there are others who know more about these lights than I do and may have even tried it.

  3. #3
    I am a caffine girl colleen c's Avatar
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    I did do the Y adpater charging thing back when I had my 808 P7 on my bike. I also had a tailight on the same circuit on the same battery with an extra Y cable so that I can charge the battery without having to unplug the lights. Never had a problem with the lighthead affecting the charging. The standby indicator light on the MS was not an issue as I thought it would have been.

    The only thing to watch out for is to be sure you unplug the charger from the Y cable before turning on the light. The current draw from the lighthead may over draw from the charger and cause a failure, although I admit I have accidently turn on the light with the charger still hooked up onn several occasion and the charger did not damage mostly because it was sharing part of the load from the battery that was also on the circuit.
    "Difference between a well dressed cyclist riding a two wheeled bicycle and a badly dressed cyclist riding a Recumbent is only a-tire"
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  4. #4
    Senior Member magohn's Avatar
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    Thanks all - sounds like its a bit dodgy then. If there is a chance that I could fry the circuit, I will probably stick to unplugging the connectors. Perhaps there is a gel or something I could put on the connectors to ease the disconnects in cold weather?

    Any other suggestions welcome.

  5. #5
    `````````````` CaptainCool's Avatar
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    You should be fine using a Y-cable. The posters above only mention problems when charging with the light on, which is kind of a dumb use case. Mechanical vs electronic switch also shouldn't matter; in either case, the light only sees a voltage supply, and the charger only sees an open/high-impedance circuit in that direction.

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    I do

    and I recommend it. I broke my 1st "Y" connector within a year, I'm sure it was the repeated connect/disconnect cycles. I have a 1 hr commute and in the winter it is full dark both ways, so I charge my lights twice a day. Having a free end to plug in and out of is much easier, and lowers the risk that I damage a connector on one of the lights, which woul dmean replacing the light or splicing in a new connector.

  7. #7
    Senior Member Looigi's Avatar
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    Quote Originally Posted by CaptainCool View Post
    Mechanical vs electronic switch also shouldn't matter; in either case, the light only sees a voltage supply, and the charger only sees an open/high-impedance circuit in that direction.
    The charger could over-voltage an electronic switch, or if an AC component is present it may interact with the switching circuit in some way. Without knowing the output of the charger and the design of the electronic switching circuit you can't know if there won't be problem. I think the likelihood of there being a problem is pretty low, but it can't be ruled out.

  8. #8
    `````````````` CaptainCool's Avatar
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    Quote Originally Posted by Looigi View Post
    The charger could over-voltage an electronic switch, or if an AC component is present it may interact with the switching circuit in some way. Without knowing the output of the charger and the design of the electronic switching circuit you can't know if there won't be problem. I think the likelihood of there being a problem is pretty low, but it can't be ruled out.
    Is there a switch out there that will work at 8.4v and break at 12v? If your main power switch can't deal with a little bit of ripple or a couple of extra volts, you have a pretty terribly designed system.

  9. #9
    Senior Member Looigi's Avatar
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    Quote Originally Posted by CaptainCool View Post
    Is there a switch out there that will work at 8.4v and break at 12v? If your main power switch can't deal with a little bit of ripple or a couple of extra volts, you have a pretty terribly designed system.
    It could be a marginal design that works reliably when used as intended. This use is different than intended and my not have been anticipated in the design or testing since the design of the system precludes connecting the charger to the lamp. We agree that the probability of problem is pretty low, but I maintain you can't know.
    Last edited by Looigi; 01-06-12 at 08:30 AM.

  10. #10
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    I didn't even think about this. Great idea!....especially for the front lights that need to be charged every other day or so. The rear ones last a long time. This way I can better secure my batteries to the bike and not worry about having the easiest access/removal. I have 2 MagicShine Tailights and they each come with a splitter I could possibly keep the battery and wires inside my seat wedge bags and make a small hole on the side for a plug in outlet....now to make some sort of removable water proof cap for it or something, unless I mount it on the bottom....hmmmm....Cheers!

  11. #11
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    I have mine set up that way with a extension cable plus the Y and keep the battery and Y in my seat bag. Since I don't ride when it is wet (not very often my location) I am not concerned about water proofing the open end of the Y and so just plug it in and charge every time my ride is finished. No problems, works great. The light head indicator does use a bit of power when the light is off but since I ride almost every day does not seem to run the battery down very fast. Am thinking about adding a power switch inline to totally isolate the light head. I have not turned the light on with the charger plugged in so do not know what the result would be if you were to do that. In short, Yes it works.

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