Charging GPS from a 6 volt motorcycle?

Discussion in 'Mapping & Navigation' started by Sidecar Jockey, May 7, 2013.

  1. Sidecar Jockey

    Sidecar Jockey Been here awhile

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    I have read about the 5 pin mini USB cables needed to charge a Garmin GPS. I have also seen the 'hard wire' kits to install such a mini USB charger directly to your motorcycle's battery.

    I do most of my adventuring on a 1978 Yamaha XT500. This is a 6 volt bike. I do NOT want to convert it to 12v.

    Will one of the 'hard wire' charger kits work on a 6 volt bike? I know they all have a little box that reduces the juice form 12v to 5v... but will this still work with 6v input?

    Or, is there any other way to charge my GPS on the bike? I only get about 3 hrs of battery life... and thats just not enough for long rides.
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  2. worwig

    worwig Long timer

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    Odds are they will not work. Most have a switching regulator that needs a couple of volts to work. So your 5 volt out needs about 7 or more in.

    You could 'roll your own' with a low dropout regulator, or LDO, as they are called.
    http://www.asciimation.co.nz/austin7/?p=632

    Or, you can get an up converter, and drive a normal 12 volt USB adapter. I get a couple off of Fleabay for a few dollars. They use the LM2577 chip. Just wire in the 6V. Adjust it for about 12V out. Wire that to a common USB 12 volt adapter. It is only good for an amp or two, but that should be fine.

    http://www.ebay.com/itm/LM2577-DC-D...172?pt=LH_DefaultDomain_0&hash=item20c4db07bc
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  3. Sidecar Jockey

    Sidecar Jockey Been here awhile

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    Thanks for the info. The first option I might* be able to make. I'm not an electrical person... I can do engine rebuilds, paint, and bodywork... but am not good at electrical.

    Where would I buy those components?

    Or, if there is a commercially available 6 votl to USB converter, I would rather spend a few extra dollars and just buy one.


    One of my xt500's has the stock charging system, so its 6 volts with a battery.

    My other xt500 is 12v AC (there is no rectifier). I'm just running a 12 volt regulator, and have all of the lights (1157 bulbs all around, and a halogen headlight) hooked up to a 20 amp breaker. The bike has no battery, or any other 'electrical' other thanhead light, tail light, and turn signals.

    Would using this bike, with it's 12v AC power be a better option?
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  4. worwig

    worwig Long timer

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    If you have a 12V AC regulator on it, you should be able to use a rectifier and capacitor. Then feed that into an ordinary 12 volt to USB adapter.


    Did you look at the EBAY bit that I mentioned? It would actually be simple. Solder on the 6 volt wires coming in. Solder on the 12 volt wires out. Run that to a 12 volt adapter. Very easy actually. (you also need to adjust the control for 12 volts) The only hard part is putting it in a box where it will be safe and dry.
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  5. Sidecar Jockey

    Sidecar Jockey Been here awhile

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    I think I'm going to go the route of the Ebay thingy you linked me.

    On my xt500 with the 12v AC regulator, I'm not running a rectifier or a battery/capacitor. Yeah, the lights dim when engine RPM's drop, but I dont do much riding at night... so its fine. It just has lights to make it road legal...

    Honestly, the only reason that the bike does not have a battery is because I couldn't figure out what 'basic' 12v rectifier to use. Any suggestions? All the ones I found had a million wires on them. All i would really need is 12v AC in and 12v DC out and maybe a ground wire. Anyone know of a 'simple' rectifier like that?

    Thanks!
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  6. Grinnin

    Grinnin Forever N00b

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    You probably need a 12V 3-phase AC in with 12V DC out. Are there 3 white wires (plus brown and green) coming out of that side of your engine? That means the rectifier should have 5 wires minimum.

    You can use 2 rectifiers from Radio Snack, (or more precisely one and a half rectifiers). This will give you DC but the voltage may go higher than the rectifier/regulators made for motorcycles.
    [​IMG]

    I had this mounted on metal as a heat sink for a while. That bike is now back to an original 1975 rectifier.
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  7. Countdown

    Countdown Long timer

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    On your headlight wires, there is an old snowmobile 2-wire 12V AC regulator that you can put right across the stator (probably high wire to chassis) then install 55/60 12V headlight bulb, then get any full wave (4-diode) rectifier and float the output, hang a cap across the line and you should have acceptable 12V for your GPS.
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  8. Whee

    Whee Adventurer

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    I have a MK3 Gas Gas Pampera that has a 12 volt AC system with lights but the only DC circuit is a rectifier controlled by a thermostat that powers the DC cooling fan. Does anyone know an inexpensive & reliable way to wire a charger for an iPhone5?
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  9. Whee

    Whee Adventurer

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    I hooked up a rectifier & a usb charger & it worked for a while with my iPhone5 & then I think I burned the charger.
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  10. Countdown

    Countdown Long timer

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    You must have a 12 V regulator across tne AC before a full wave rectifier. Without checking with a volt meter, you are literally playing with fire!
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  11. Whee

    Whee Adventurer

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    have a 12 V regulator across the AC before a full wave rectifier
    [
    QUOTE=Countdown;23104880]You must have a 12 V regulator across tne AC before a full wave rectifier. Without checking with a volt meter, you are literally playing with fire![/QUOTE]
    #11
  12. Whee

    Whee Adventurer

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  13. worwig

    worwig Long timer

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    Did you measure the AC voltage before the rectifier?
    Did you measure the DC voltage after the rectifier?

    Even if the voltage is reasonable, you would still need a filter capacitor across the DC going to the USB adapter.

    Other then that, I would think it would be OK.
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  14. Whee

    Whee Adventurer

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    ... for your reply! I have measured it but don't have the figures in front of me. The AC headlight had been burning out until I replaced the regulator but now it is fine but I guess the regulator doesn't do a good enough job to keep the USB adapter from burning? Any suggestions on the filter capacitor required? Would a small 12 volt battery do the same thing?

    #14
  15. NorthernTraveler

    NorthernTraveler Long time Adventurer

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    I designed a power board 10-15 years ago that allows me to convert most any power on a bike to whatever voltage DC out that I want.

    I originally did it for a Garmion eMap which takes 3.15 volts.

    I've built them for 8-9 volts to power the 4 pin round plugs for my 76cx.

    I recently built a batch for 5v for powering some Nuvi's via USB.

    You can fry them - I've burned a couple on my XR200R's, but that basic AC regulator holds them low enough. They fry if you overvolt them by 40 volts more than the output.

    They whole deal is molded in epoxy in an ice cube tray!

    AC or DC in, it goes through a bridge rectifier, filter cap, adjustable regulator, filter cap, power out indicator LED, the out to the device.
    #15
  16. worwig

    worwig Long timer

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    I need to know at least the AC voltage.
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  17. foxtrapper

    foxtrapper Long timer

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    Have a xl500 myself, with 6 volts. Fretted as you. Then based on some info I received regarding the design of most cigarette lighter USB chargers, I tried mine directly on 6 volts. All but one worked just fine.

    For me, it was problem solved, and I simply put a cigarette lighter outlet on my handlebars, and plug into that.
    #17
  18. Schmokel

    Schmokel Jazz hands!

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    I know its an old thread, but I'm going to bump this back up.

    So the way I'm reading this, you just wired in a cigarette lighter and plugged the GPS right into that?

    This is for an '86 Honda XL250R.
    #18
  19. worwig

    worwig Long timer

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    A friend of mine has a Model T. He 'tours' southeastern Ohio in it, and uses a GPS to keep him way from high traffic roads. He wanted to run it off of the 6V. I sent him a unit that I bought off of Ebay for a couple of bucks. It was like 3 of them for $5 maybe. It up converts most any voltage, to most any voltage. The one I gave him is good for about 1 amp, and he used it to adapt the 6 volts to 12, to a cigarette lighter socket, to charge his GPS or cell phone.
    I bought them to charge a 12 volt battery in a trailer. I needed 14.5 volts at the battery, from a long wire that was only about 13 volts, maybe. It worked as expected pumping the 13 up to 14.5, but the 1 amp current was too marginal and ran way too hot. I just bought a bag of higher current versions. It works very well, at over 2 amps, and a lot less heat. (don't forget the diode if you want to charge a battery)
    Get a couple of these, 6V in to a cigarette lighter.
    http://www.ebay.com/itm/261835473511?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT
    #19
  20. Schmokel

    Schmokel Jazz hands!

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    Hm. So buy that unit, run the + and - side of the battery on the "in" side, and a cigarette light on the "out" side?
    #20