# 12-volt UPS for my motorcycle



## NaeKid (Oct 17, 2008)

A little bit of a background. I spend alot of time in the great outdoors far away from most forms of electronic communications, but, I do carry my GPS with me. When I am in one of my Jeeps or have my solar-powered camping-trailer along, I have a way to keep my GPS charged up and running. When I am out there with just a tent and my Kawasaki KLR650, I need a reliable way to keep my GPS (and similar electronics) functional.

In my attempt to keep my GPS running, I hardwired-in a "weather proof 12-volt to USB converter" from PrincessAuto ( http://www.princessauto.com/pal/pro...ous-Automotive/Weather-Proof-USB-Power-Outlet ) (kind of Canadian version of TractorSupply or HarborFreight). The problem that I have run into is the fact that when I am riding my motorbike, the GPS tries to shut-down and then start-up and then shut-down again - and the cycle repeats often. I have tried two different GPS's and four different connector cords to try to fix the problem and I have not had any difference between the different manufacturers (Garmin and Magellan).

I have checked all the connections with a volt-meter and wiggled everything all around and I haven't had any success in finding a bad connection anywhere. For those who might have a KLR, I have my USB converter wired into the "City Lights" circuit.

What I am looking to do is have a 12-volt based UPS (Uninteruptable Power Supply), but, because I am on a motorbike, I need something that would be weather-proof, shock proof (shock as in vibration or falling over) and I need it to be simple to work on deep in the back-country if something were to fail.

What I am thinking of doing is using a fairly small "Radio Shack" project box that I can seal-up and running the positive and negative leads into the box to a basic project circuit board. At the start of the circuit board, I would like to put a red LED to show that power is flowing from the bike to the project box - that LED might flash if there are power-drops - but - it would be used primarily as a basic diode for flow-control of the power. From that LED, I would like to put a small bank of capacitators (I was thinking of ten 1000 micro-farad capacitators because I can buy them fairly locally for about $5) and then put a second LED on the "exit-side" of the project box (lets call this one green) to show that power is flowing properly through the project box to the USB connector. If things go well, the green LED will never flash like I would expect the red one to do.

Does anyone see any problems with doing something like this - any issues with vibration from a large single-cylinder motorcycle that travels gravel-roads / trails for fun?


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## backlash (Nov 11, 2008)

Why not wire the USB directly to the battery?
That would eliminate any loose wiring and it would be the same as a UPS.


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## NaeKid (Oct 17, 2008)

If I did that, then the USB-port would be "always on". A motorcycle battery probably wouldn't last very long running even that little amount of draw (inside the converter there seems to be a small capacitor and voltage regulator) 24hrs a day. It supplies 5-volt all the time, doesn't matter if it is used power or not, with a draw of about 0.5 amp. The city-lights circuit is an ignition-switched circuit as shown by the wiring-diagram attached (US-models do not have the light attached, the euro-models do) ... that same circuit also powers the always running tail-light.

It is possible that there is a bad connection at the ignition-switch, but, wigglin' the wires there doesn't make my volt-meter flake-out and my tail-lights stay solidly lit ... :dunno:


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## backlash (Nov 11, 2008)

My guess would be the 12v is not stable when the bike is running.
Unless you are using an analog meter so you can see the needle fluctuating it would be hard to spot.
If you had an oscilloscope you would probable see the 12v oscillating when the bike is running.
A simple test would be to just wire it up to the battery and see if that solves your problem and then work on a way to completely disconnect the USB if it does.
Use a on/off switch or wire in a plug so you can disconnect the USB cable when it's not needed.


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## FatTire (Mar 20, 2012)

Why not hard wire it to the batter, but put in a toggle switch?


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## NaeKid (Oct 17, 2008)

backlash said:


> My guess would be the 12v is not stable when the bike is running.
> Unless you are using an analog meter so you can see the needle fluctuating it would be hard to spot.
> If you had an oscilloscope you would probable see the 12v oscillating when the bike is running.
> A simple test would be to just wire it up to the battery and see if that solves your problem and then work on a way to completely disconnect the USB if it does.
> Use a on/off switch or wire in a plug so you can disconnect the USB cable when it's not needed.


That is always possible - I could locate an "all-weather" power switch and then make a mount for the switch and then just have to remember to turn it off when I get off of the bike. What I am really hoping for a dummy-proof solution that could give me about 10 seconds worth of a power-buffer - meaning if I turn off my bike (or have to hit the starter-switch), the GPS wouldn't instantly go into shutdown mode - it would play nice and stay on just a little bit longer without me having to reach down to the "stay-on" button on the screen ... and then watch it as it goes through its initializing-screen all over again.


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## Tirediron (Jul 12, 2010)

I don't know if DRL systems on bikes have voltage drops built into the system like many automotive systems but maybe that is the problem, or the inverter has too narrow of a source band.


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## stayingthegame (Mar 22, 2011)

Why don't you wire your power connector to the battery with a fuse rated for the power connector amperage . On the power side, wire the fuse, then a relay between the battery feed and the power connector. This way the power connector can make full use of the current but you use the relay so you don't need a big switch for control. Use the ground and pick up a wire that is hot only when the M/C is running, or run another wire from the battery to a LIGHTED switch so you can turn the Connector on and off manually without switching the load. That way, you have power when the M/C switch is on and it is interrupted when the M/C is off.
I am concerned that using an LED diode to block current flow wouldn't be good because you don't know the PIV (Peek Inverse Voltage) of the diode. You could burn up the LED.
You could use the connections that you have already and wire a light bulb (Filament) type to the Power connector and watch if the light blinks when you ride. In my opinion, it sounds like a bad ground or a loose wire at the switch of the "City Lights". With the relay and direct wire to the battery, you can avoid this. Hope this helps.


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## NaeKid (Oct 17, 2008)

stayingthegame said:


> Why don't you wire your power connector to the battery with a fuse rated for the power connector amperage . On the power side, wire the fuse, then a relay between the battery feed and the power connector. This way the power connector can make full use of the current but you use the relay so you don't need a big switch for control. Use the ground and pick up a wire that is hot only when the M/C is running, or run another wire from the battery to a LIGHTED switch so you can turn the Connector on and off manually without switching the load. That way, you have power when the M/C switch is on and it is interrupted when the M/C is off.
> I am concerned that using an LED diode to block current flow wouldn't be good because you don't know the PIV (Peek Inverse Voltage) of the diode. You could burn up the LED.
> You could use the connections that you have already and wire a light bulb (Filament) type to the Power connector and watch if the light blinks when you ride. In my opinion, it sounds like a bad ground or a loose wire at the switch of the "City Lights". With the relay and direct wire to the battery, you can avoid this. Hope this helps.


If you take a peak at the wiring diagram that I uploaded, what you describe is basically what is already there and I am just taking advantage of the existing system instead of trying to re-invent what is already there. My KLR doesn't really have alot of room for all kinds of extra wiring and components, so, whatever I do has to be fairly compact. When I first started on my quest to have clean power to my GPS I had originally thought it was a bad connection somewhere. After pulling everything apart and using a volt-meter to check every possible connection from the battery to the end of the USB connector and using two different GPS and four different cables and then using "open ended" USB cables (cut free from dead keyboards) to check the voltage coming out of the cable, I finally started to think that it might be a problem through the regulator/rectifier. I am starting to guess that as the regulator/rectifier switches from charge-mode to maintain-mode and back again that it might be spiking the power. The motorcycle battery is between the regulator/recitifier and the city-lights circuit, so, I would have figured that there would have been a good enough buffer to clean the signal.

On another site I am on, they are saying that vehicles never have a clean signal which is the reason why many of the high-end stereo systems have multi-battery and multi-alternator and multi-capacitator systems installed - motorbikes have even less of a clean signal than your average car. My GPS might be picking up on the dirty signals and it might be getting confused enough that it says "screw it, I shouldn't be workin' no more" and it wants to take a break - then it gets enough power-signal and then is says "ok, maybe I should keep on working again" ... and so-on ... 

On another note, I have a handlebar switch on order (it should be here in the coming week) that I was planning to use for a set of LED driving lights (known as the 24x7 DIY LED lights) through an eBay seller - I wanted to also tie into that same CityLight circuit to run those lights off of the switch ... so it will be a case of pretty driving lights and the GPS all running off of the same two-wires, but, before I do that, I need to make sure that the GPS side of the system is good before I go and mess it up again.


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## stayingthegame (Mar 22, 2011)

why are you using a usb cable - usb is for +5volts and has a current limiting resistor built in on some plugs. GPS needs +12 volts. The GPS could be loading down because of the current. If you are worried about a filter, use the battery with a choke which will filter most noise. If you want to clamp a voltage, use a zener diode but be sure it can handle the amperage draw. use a 5 watt and wire it between the +12volts and ground which will clamp the voltage to 12 volts. Maybe I don't understand why you are using a usb and 5 volts? R U monitoring the current in series to see if you are getting enough current and that it is not causing the voltage to drop because of the limited current. Also, the reason that large stereos use multiple batteries, alternators is because when an amp is trying to reproduce bass, the current draw is exceeded through the wire and the voltage drops out. an Electrolytic capacitor will charge in 5 time constants and will help to maintain the voltage. 
If you want to keep the GPS on for about 15 seconds, you can use a 555 IC timer with a circuit that will hold a relay up until the capicitor drops out causing the relay to drop out.
Again, please make sure that your GPS needs 12 volts and not to use 5 volts. It may work on 5 volts but because of the limited current, it will drop out nd recycle.


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## NaeKid (Oct 17, 2008)

One of my GPS-units is an Magellan eXplorist 400 and the other is a Garmin nuvi 550 - I do have other GPS units as well, but, those are the primary ones that I carry on my motorbike due to their all-weather nature. Both of the GPS units data-transfer and charge directly off of the USB-port attached to a computer and the Nuvi comes with a standard cigarette-lighter to USB converter. I have also sucessfully used a generic cigarette-lighter/USB unit to run and charge both of the GPS's .. so, I am pretty sure that the 5volt will be more than sufficient to run either one of them.

Attached is a picture of my Magellan on my motorbike and a picture of a generic converter similar to what I have several times over and a close-up picture of the weather proof USB power outlet. Many other motorbikers have installed and used the exact same USB-outlet on their bikes without issues, but, I haven't heard of other KLR-riders using the same one. BMW, Harley, Honda cruisers have used it with great success.

I hadn't considered the 555IC timer - that might help make sure that the power continues to flow through ...


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## Tex (Oct 31, 2008)

I would install filter to clean up your DC voltage. It's as simple as adding a capacitor across your circuit and an inductor inseries with your circuit. If you can find accessory power, you can use that to feed your circuit or use it to switch your circuit on with a relay. You might can find a prebuilt.filter at a stereo shop. They use.them to filter engine noise out of radios. Also, a zener diode will help filter your power

Or you could try something like this.

http://linuxcar.sone.jp/reg.en.html


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## LincTex (Apr 1, 2011)

I agree with the suggestion to "ax" the USB cable.

Use a standard "lighter socket" 12v-to-?volt what ever the GPS wants. Changing 12 volts to 5 volts USB, and then changing the voltage AGAIN is overly complicating things.

Forget the whole USB idea and just use a 12 volt lighter socket adapter. You can open it up and the take the insides out and make it 10% the size of what it was.


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## BMyers (Oct 13, 2012)

The cig lighter that came with my Garmin is 5volt out at the plug for the unit. Delete the voltage reduction in the lighter adaptor and you'll delete any usefulness the GPS used to have!


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## Tex (Oct 31, 2008)

I agree with Linctex. Find a 12V wire that is switched on only when the engine is running and wire in a 12V socket. It can be a light circuit or a horn. Anything that only works when the ignition is switched on. I'd use a higher amp circuit so that you are less likely to overload it or add a circuit with a relay controlled from a switched source, but that adds complexity and bulk.


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## BMyers (Oct 13, 2012)

I would do a low level switched circuit to energize a relay for this


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## LincTex (Apr 1, 2011)

BMyers said:


> Delete the voltage reduction in the lighter adapter....


Huh? No one suggested that. 
I said to take the internals and move them into a smaller container. "Lighter plug adapters" are always about 20 times larger than needed once you take them apart to see what is inside.

I have even encapsulated the "guts" (circuit board) in epoxy resin and discarded the "plug" portion altogether when hard wired into a 12 volt circuit (which is something I do often) because I don't care much for lighter plugs.


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