Dynamo + E-Werk + Outbound light = ???- Mtbr.com
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  1. #1
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    Dynamo + E-Werk + Outbound light = ???

    I'm exercising a hare-brained idea here. I currently run Outbound lights for endurance/ultra races. For lap-races, it's no hassle to swap battery packs in the pits. For some of the ultra stuff, however, I load up 4 battery packs and hope that it gives me enough burn-time (I think I eked ~22 hours out of the batteries on my last ride, running the lamp entirely on low, with a few hours left to spare).

    I am considering a dynamo set-up and would like to continue to use my Outbound lamp if at all possible. On paper, it would seem that I could run a dynamo hub with a B&M E-Werk set to 8.4v output to charge my 7.4v battery.

    I'm assuming the Outbound lamp is pulling about .7-.8 amps on low, since I get around 8 hours out of a 6.2Ah battery. If I set the E-Werk output to 0.5A, I'd have ~0.3 Ah drain on the battery, which I could recharge the following day when the lamp is off. (I'd consider using my smaller 2.9Ah battery to further save weight/space)

    Could I run the E-Werk and lamp connected to the battery simultaneously using a y-splitter, to effectively extend the life of the battery as described above? I.e. Dynamo to E-Werk input, E-Werk output to y-splitter to battery and lamp. If the E-Werk output were less than the current draw on the lamp, I wouldn't have to worry about overcharging the battery when the lamp was on (only when the lamp is off...my Glowworm packs have an LED battery meter, so that could help keep tabs on that). Or, would I need some sort of pass-thru circuit? I.e. B&M instructions only show the E-Werk being wired parallel to the existing dynamo-light circuit, so I think I'd circumvent the need for a pass-thru circuit by wiring it in series?

    Thoughts or experience? Thanks in advance!
    Last edited by VegasSingleSpeed; 12-20-2018 at 08:01 AM. Reason: corrected battery spec's

  2. #2
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    The Li Ion battery pack has specific charging requirements. The wall wart charger provided with the Outbound Lighting headlamp satisfies those requirements.

    Ensure that any solution provides safe electrical and thermal handling of the battery pack.
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  3. #3
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    Battery chargers are generic, and are specified for a current somewhere between "recharging annoying slow" and "getting close to the current limits of the battery"; and, where you land on that continuum contributes to the ultimate lifespan of the battery pack (# charge/discharge cycles).

    Although I'm not using OL's battery packs, unless the PCB on the pack has a minimum-current cut-off (I've never heard of this), I don't see there being an issue with charging at 0.5A...it's just going to take longer with the dynamo than a 1.8A battery charger (I have all day), and I'll have to keep tabs on the battery monitor to disconnect the E-Werk when the battery is full.


    Any folks with experience using the B&M E-Werk? I'm more concerned with 1) whether the E-Werk will function in this capacity, and 2) if having 8.4v output from the E-Work wired parallel to the 7.4v output from the battery is going to cause any issues running the OL lamp.

  4. #4
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    I don't have any experience with dynamos, but here's an outfit that does. The info may be on their site or they may be able to answer your questions...

    https://www.peterwhitecycles.com/lightingsystems.php

    Here's they're info on the E-werk: https://www.peterwhitecycles.com/ewerk.php
    Do the math.

  5. #5
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    Quote Originally Posted by VegasSingleSpeed View Post
    Battery chargers are generic, and are specified for a current somewhere between "recharging annoying slow" and "getting close to the current limits of the battery"; and, where you land on that continuum contributes to the ultimate lifespan of the battery pack (# charge/discharge cycles).
    I'll preface my reply be saying I'm not a charger or Li-Ion expert and only an sharing what I have read and observed with charging Li-Ion cells for my own lights.....

    A Li-Ion charger is not a constant current device. It will charge at 8.4V and as the battery voltage rises the charge current drops off. The best/faster chargers don't do that linearly, but on a curve.

    I have monitored the charging of the 2 chargers I use most. They "pulse" the charge with a few seconds on then a few milliseconds off. During the off time, I believe the charger circuitry measures the battery voltage, then the charger resumes charging and as the voltage measured rises, the current is reduced.

    A good explanation about Li-ion charging...

    https://batteryuniversity.com/learn/..._ion_batteries

    The operation manual for the e-werk is pretty clear that it is a constant voltage and current device and will overcharge Li-Ion batteries if left connected once the battery is fully charged. It would be up to the user to monitor the battery being charged and disconnect it when near full. It's not going to be real battery friendly doing it like that.
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  6. #6
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    Quote Originally Posted by Vancbiker View Post
    I'll preface my reply be saying I'm not a charger or Li-Ion expert and only an sharing what I have read and observed with charging Li-Ion cells for my own lights.....

    A Li-Ion charger is not a constant current device. It will charge at 8.4V and as the battery voltage rises the charge current drops off. The best/faster chargers don't do that linearly, but on a curve.

    I have monitored the charging of the 2 chargers I use most. They "pulse" the charge with a few seconds on then a few milliseconds off. During the off time, I believe the charger circuitry measures the battery voltage, then the charger resumes charging and as the voltage measured rises, the current is reduced.
    I get that; my comment was more directed at the notion that the OL wall-wart is somehow a guideline to follow. You can charge the the OL pack (or any other 4-cell pack) with a charger well above the rated current on the OL charger. The difference will be the current during that initial CC phase and, as you describe, the (curvi)linearity of the CV phase...and, the resulting life of the battery.

    Quote Originally Posted by Vancbiker View Post
    A good explanation about Li-ion charging...

    https://batteryuniversity.com/learn/..._ion_batteries

    The operation manual for the e-werk is pretty clear that it is a constant voltage and current device and will overcharge Li-Ion batteries if left connected once the battery is fully charged. It would be up to the user to monitor the battery being charged and disconnect it when near full. It's not going to be real battery friendly doing it like that.
    But, I'm proposing that I charge the battery at a significantly reduced current. 0.5A is .08C on my 6.2Ah battery pack, which would significantly prolong the constant-current phase of the charge cycle, and significantly reduce the saturation phase, if it were needed at all (...the internet says no?). So, monitoring the battery pack (as I've stated twice already) should minimize/prevent over-charging.

  7. #7
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    Sounds like an interesting idea.
    I'd ask Outbound if it is possible to use y-cable for constant charging during using the lamp.

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