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Adding switchable power for USB charger.

Discussion in 'XJ DIY How-To Instructions' started by Nuch, May 29, 2017.

  1. Nuch

    Nuch Well-Known Member

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    So, Like many of you I'm sure you have a battery tender. I have one of these...

    01_tender.jpg

    There's a fused quick connect wire (let's call it a pigtail... left-most item in picture above) that stays on the battery and whenever I roll back into the garage, I plug it into the power pack that stays plugged into the wall.

    For charging the phone while riding, I added one of these...

    02_USB.jpg

    When the pigtail is not being used to tend the battery I can plug this little guy in, to convert the battery power to USB and send that "juice" via a charging cable, up to my handle bars where my phone happily sits in the mount. It physically resides behind the right side cover in that plastic compartment that is there.


    The problem was that every time I wanted to charge the phone during a ride, I had to remove the cover to do the swap. This bothered me because we all know what happens to +30 year old plastic parts if you're constantly diddling with them... Crack!


    As I didn't want that to happen, I thought I'd just get another pigtail and leave it plugged into the USB converter all the time. So I bought another one...

    03_quick_disconnect.jpg

    After a chat with our beloved Hogfiddles, he suggested that I NOT leave it plugged in all the time for risk of a parasitic draw on the battery. But rather, wire in a switch...

    Here's what I did....
     
    Last edited: May 29, 2017
  2. Nuch

    Nuch Well-Known Member

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    I started with some basic flat stock that had the holes already...

    04_stock.jpg

    Then I cut it to the needed length, did a rough grinding, drilled one hole larger for the switch and planned the next cuts...

    05_stock_rough_cut.jpg

    More cutting and grinding...

    06_stock_detail_cut.jpg

    Then into the vice…

    07_stock_in_vice.jpg

    Adding some heat gave me a nice fold in the metal, exactly where I wanted it…

    08_stock_hammered.jpg
     
  3. Nuch

    Nuch Well-Known Member

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    Here it is after the bend.

    09_stock_out_of_vice.jpg

    Then I took some bicycle tube rubber and made a gasket so the bracket wouldn’t scratch the fender… it also got painted with a rustoleum silver at this point...

    10_outline_stock.jpg
    11_stock_gasket.jpg

    Here’s how the switch sits in the bracket. It’s a simple two pole variety…

    12_switch_through_stock.jpg

    Then I fit the bracket between the fender and grab rail and installed the switch and wired it in….

    13_bracket_in_place.jpg
     
    Last edited: May 29, 2017
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  4. Nuch

    Nuch Well-Known Member

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    After another discussion/picture messages of the completed job with a very detail oriented XJ’er who wasn’t happy with being able to see the wires… (cough… Hogfiddles)… I pulled it all apart again. I made this ridiculously easy modification at his suggestion and bent the poles down for a lower profile…

    14_prongs_down.jpg

    and of course it looks waaay better now and you really can’t see the wires at all…

    15_switch_in_place.jpg
    16_completed_job.jpg

    Here you see how I modified the pigtail to include the switch….

    17_harness.jpg

    Essentially, I split the positive lead and added extra wire to reach the location of the new switch. I used an old toggle that I had, but may swap it out for a newer/weather insulated one. For now it works and I have switchable power. The set up works great and the switch really is in an inconspicuous place, easily reachable even when riding.
     
    Last edited: May 29, 2017
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  5. XJ550H

    XJ550H Well-Known Member Premium Member

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    you will want to use a weather proof switch
     
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  6. Nuch

    Nuch Well-Known Member

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    Agreed.

    I was thinking that this one would do...

    https://www.delcity.net/store/Sealed-Toggles/p_807270.h_807271

    Funny how having the moment to get something done and actually having the parts to get it done are rarely aligned.

    I'll be swapping it out, but the foundational work is done!
     
  7. kosel

    kosel Active Member Premium Member

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    I haven't dug into it, yet, but a PO wired in a power adapter (for a radar detector, I think) into the headlight (at least the wires run into the headlight bucket). So, I'm assuming it's on the same circuit as the headlight, making it switched. Any problems with doing the same with a USB charger?

    For now, I used the same pigtail as Nuch, but ran it to the space under my seat. When I need it, the cord runs from under the seat, across the top of the tank, to the phone that's sitting on top of the tank bag. It's easy enough to lift the seat and unplug the USB adapter and tuck the wires into the very small space under the tank. Not switched, but just took a few minutes.
     
  8. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Nuch-----That looks 30000% better :)

    Dave
     
  9. Polock

    Polock Well-Known Member

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    you do nice work but you really didn't have to. i had a regular car usb charger wired right to the battery and never had a problem.
    now if you only ride around the block once a month, that switch might help.
    as long as it's there, might as well put a led on it so you remember to turn it off
     
  10. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Ooooh, yeah!!!
     
  11. Nuch

    Nuch Well-Known Member

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    I knew you'd like that...
     
  12. Wintersdark

    Wintersdark Well-Known Member

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    Stumbling in pretty late, but figured I'd pop a question:

    Why not just wire it with the ignition switched power? Say, the +12v line for the horn? Then it'd only be live while you were riding - I imagine you're not looking to charge your phone on your bike while it's parked after all. And I know from previous experience a phone can take a fairly significant chunk from a motorcycle battery; it's not impossible to drain it below the ability to start it again, particularly if you're in conditions that are otherwise straining the battery.

    Obviously, being put together already with a switch pretty much means the above is pointless, but it seems an easier solution?
     
  13. Nuch

    Nuch Well-Known Member

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    Winter... I like your idea. I'm sure it would work, but Im scared to touch any of my stock wiring as it has not given me any trouble yet (knock on wood!). I am amazed with how electrical works and equally confused by it (I think it might be magic). This allowed me to add the switch while only cutting into the additional pigtail.
     
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  14. XJ550H

    XJ550H Well-Known Member Premium Member

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    what if you want to charge your phone when not riding the bike? you would not want to have to turn the key on with bike not running .

    the xjs that had faring options have a few extra wires in the headlight bucket my 750 has an extra hot wire and an extra ground not sure about the 550.
    you could make a splitter to plug into existing connector recepticals to ad a usb connection . see if chacal sells the dual ground connector lug
    and bullet then you could hook up where power is available. it would be nice to have charger fused in caseit fails and shorts or starts overdrawing current.
     
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  15. Wintersdark

    Wintersdark Well-Known Member

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    Well:
    I get wanting a switch, and certainly wouldn't call it a bad idea. I'd even say it was a better choice, if you didn't have a mount for your phone and wanted a means to get a small emergency charge when you weren't riding.

    I was just throwing that out there as a better way to go safely, at lower cost/complexity, no danger of forgetting that switch being on, and no temptation to charge your phone from your bike when it's parked, because:

    A full charge on a modern phone takes a surprisingly large chunk of juice - you're looking at a capacity somewhere around 3.8Ah at 5v. Phones will charge at 5v1.5A (unless USBC, which can use much higher voltages, but we'll ignore that). Assuming 80% efficiency with a pretty good charger (very good, when you consider the step down regulator and normal losses when charging), we're now up to 1.76A@5v or 0.74A @ 12v. Average motorcycle battery is roughly 14Ah@12v IIRC, so two hours of charging is using 10% of the batteries full capacity. Feel free to correct my math if I screwed anything up, I'm a bit of a dumbass that way and it's really late =)

    Now, in a car, that's less of an issue, but our XJ's get really sketchy when cranking voltage drops. Under normal circumstances, this shouldn't be a problem, but how much can you take from the battery before it may not start reliably? I get nervous about getting stuck somewhere with a dead battery that doesn't push enough voltage to get a good spark. What if it's cold, or you've been taking a bunch of short trips about so there's been lots of starting and little 4k+RPM charging?

    All this DOES hinge on my not having any idea how much you can draw from the battery before it won't start, in terms of percentage of total charge. As well, maybe my math is horribly wrong - wouldn't be the first time, certainly won't be the last. But I'd think, for future folks wandering through the thread, that they ought to consider using an ignition switched source as it removes that temptation, potential problem, and complexity... and in how many situations, assuming you've got a mount for your phone and already plan to charge while riding, are you going to want to charge when NOT riding? I know I'd never leave my phone on my bike charging when I'm not there, because my phone costs more than my bike does. If I'm parked somewhere, I'm almost certainly near an outlet, so I could charge that way. If it was an emergency - my phone was dead and I needed to make a call - I could just flick the ignition on and get enough of a charge to do that.
     
  16. XJ550H

    XJ550H Well-Known Member Premium Member

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    I guess it would be best to make sure your phone or other device was fully charged before riding,

    the usb port on your bike is like the phone just an accessory a whistle and bell...............but it is so much a part of so many peoples daily life they would die or stroke out if they did not have their phone , so affraid to be "off the grid" comm wise.
    I do not understand the phone thing anyways. just got to work, just punched it, walking to my work area , my nose itches . .......................................
    I have a flip phone that stays charged for days but it does take photos. I use my phone about 5 min a day at most, because life is to short
     
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  17. Polock

    Polock Well-Known Member

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    i just happened to have all this stuff out right now so here's the measured numbers.
    battery, 11.6 volts, 3S 2200ma lipo (from China) :)
    usb charger board from ebay
    idle current-9ma
    charging a 8 inch tablet from 50% charge-20ma
    when a lipo battery like your fone charges, the initial current is high, then tapers as the battery charges. the 20ma from a 50% charge doesn't tell a lot
    but 9ma not charging, isn't much.
    i'll have to let the tablet die and do it again
     
  18. Wintersdark

    Wintersdark Well-Known Member

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    Oh, man, those are way low numbers. You're looking at a cheap tablet or battery and charger there (pr a very poor cable!) and those are very misleading numbers.

    Keep in mind cable matters. Chinese parts here use small gauge wires that can't deliver full current - a USB meter is really useful to figure out which cables won't deliver full power due to internal resistance. For example, a cheap Chinesium MicroUSB cable will charge my Sony Z3TC tablet at 5v 500mA, while a good MicroUSB cable will deliver 1.5A.

    Basic USB 2 with no quick charging (only really old/cheap devices) will charge at max 5v 500mA (this is the raw USB 2 power spec, to be certified it must deliver that)

    I can provide pics with my meter if you doubt it, but using MicroUSB with Quick charge 2.0, a 4 year old major Android device from will pull 1.5 amps (not milliamps) at 5v measured at the phone.

    A phone such as my wife's Samsung Galaxy Note 5 (still a couple years old) with Quickcharge 3.0 will take up to 3 amps at 8v. USB-C, the new standard, will charge at up to 20v 5A - literally 100 watts. Current USB C devices don't go that high and top out at 12v 1.5a but that will certainly increase with newer devices.

    For example, this cheap car carger will provide 15 watts over MicroUSB and 20 watts over USB C: https://www.amazon.com/gp/aw/d/B01H...tDescription_secondary_view_div_1500823793526

    Modern flagship phones are all roughly 3800mAh batteries, and once the phone is powered and able to use Qualcomm QuickCharge, it'll ramp up the current (and voltage if applicable) and hold it up there until roughly 75% charge. Only after 75% will it drop the charge rate down.

    This all matters, because people are (as can be seen in this thread) typically very much unaware of just how much power a modern smartphone/charger can use charging.

    You don't need special equipment for that either - just wiring up your manufacturers car charger will do it.

    As an aside, these meters are really valuable if you find your phone taking a long time to charge. They're only a dollar on eBay, and totally worth it.

    Attached are pics of my tablet charging at 5v 900mA, and (not sure if you can read the battery percentage in the top right) it's at 90% charge so has really dialed back the charge rate. Keep in mind, this is a nearly fully charged small tablet and is still pulling that much... And this is an old, cheap QC 1.0 charger that will only deliver 1.5A max per channel/2.1A over two channels.
     

    Attached Files:

  19. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    I just ran mine staight to the battery. If you use a decent-quality waterproof socket and fuse holder there won't be any parasitic draw. Mine is set up to run my GPS, or phone, or air pump, and to serve as the port for my batery tender.
     
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  20. XJ550H

    XJ550H Well-Known Member Premium Member

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    if charging draws that much current that is all the more reason to have its own fuse and circuit instead of drawing through the main fuse and other fuses which draw off of the main fuse.

    but you do mix apples and oranges
    1 amp at 5 volts is not the same wattage as 1 amp at 12 volts.
     
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