When I use my Mio C220 GPS on my bike the battery doesn't last long. This sucks. Especially for those long trips. Also, It would be cool if I could charge my cell phone and mp3 player on the go.
The solution:
Add a powered USB port, hooked to the battery, for everlasting power.
The dirty details:
First of all, you'll need an 7805 voltage regulator A.K.A. LM7805, a diode, a fuse, some cable, and a female Type-A USB port.
While you *could* wire up everything on your own, there's no point doing so.
For about 1 Euro you can get a USB car charger, from ebay. (Postage included)
It would cost you more to get the individual parts, plus you would have to find some sort of case to protect them. For 1 euro you get everything you need. Sweet deal.
Carefully dismantle the car charger.
If it includes a fuse, you're lucky. Mine didn't. It's fifty-fifty. Some have a fuse, some haven't.
Although you could get away without using a fuse, I highly recommend it. We don't want to burn down our beloved bikes, do we?
Get rid of the spring either by cutting it, or de-soldering it. This is the positive output of the circuit.
Also throw away the metal contacts. We don't need those either. Just try to keep the little black cable intact.
It's easier to solder on the cable instead on the PCB itself. Black equals ground, or negative.
This is where I connected my 2 amps fuse. I'm not sure whether you're supposed to wire it on the positive or the negative lead, but I don't think it matters much.
If you have a multimeter it's a good idea to test the connections to make sure you've soldered everything correctly.
Now connect positive to positive, and ground to ground on your battery screws, and wait for the fireworks. (Just kidding). Just take extra care not to connect them the other way around, or the voltage regulator will get red-hot and start melting everything.
Now wire a mini-USB cable that runs from the battery, through the bike's frame, to the handlebar.
This way you can charge your GPS and use at the same time.
And if I ever need to charge something under the saddle, I can always unplug the handlebar cable and plug any USB charger under the saddle.
The only problem with this configuration is energy waste. All the excess voltage is converted into heat. This isn't just wasteful, it's also a small flaw: When the engine is running, the voltage on the battery gets up to 14V, so the regulator has to drop it to 5V which is quite a drop. The specs for 7805 specify that it can take as input as much as 35V with a heatsink. In this case I'm not using one, plus everything is encased, and under the seat. Depending on your motorcycle, things might get very hot.
My Aprilia has the engine air-intake under the seat so I'm hoping to get some air-stream on it that will help cool it down.
My next upgrade will be to perforate the plastic so that it "breaths" better.
6 comments:
So how is this mod holding up for you? I am really interested in trying this myself for a long distance ride I am going on in a few weeks. Any feedback would be awesome.
Actually it didn't work that good.
It's absolutely fine for charging devices while they're off, but 500mAh is not enough to charge and keep them on at the same time. I only get one hour of navigation out of my Chinese 5 inches GPS.
I'm trying to find a 1500mAh charger to install.
I'll let you know how it goes.
Thanks for the writeup. It's a really great idea.
Rather than a generic usb charger I'm getting one compatible with my Droid phone. Hopefully that will solve the charging issue.
I found-out what went wrong. It wasn't the mAh output, but rather a problem of overheating.
When the charger starts to heat-up after a while, the voltage drops.
I drilled some holes for better airflow and glued a heatsink on.
Now it works flawlessly.
I even installed a second charger with a tiny fan, to power my GPS tracker at the same time.
No need for an expensive chargers. Get the cheapest one from ebay.
What exactly did you glue the heatsink to? I can imagine the only thing getting hot was that capacitor? Maybe the fuse? Specs on the heatsink and where to buy? pictures of the final product?
That metal thingy just above the fuse is the transformer's own heatsink. It's not sufficient. I used fast-dry epoxy to attach an old GPU heatsink I had laying-around. If you don't have one you can buy it off ebay. Just search for GPU or northbridge heatsink.
Post a Comment