External 12v Power for the Zumo 660 GPS

So I have been struggling with how to connect my GPS to a source of power so that it doesn't run out of power while I am riding. Quick recap on this: the Zumo 660 has a ~6.66Wh Lithium battery which runs the Zumo for ~2 hours on full charge after which it goes dead. Since I want it to run for longer, I need to run power to the Zumo from my scooter alternator, i.e. Alternator-> Rectifier-> 12V Scooter battery-> GPS.

So what I need to do is the following

1. The Zumo handlebar mount comes with two bare wires (see previous post), which need to be connected to the scooter battery.

2. However, due to the number of vandals in London I cannot connect the mount directly to the battery. If I did, I would have to leave the mount on the scooter all the time, which would almost certainly result in someone tearing it off out of spite or to sell it. Therefore, I need a detachable connector between the Zumo and the battery of the Vity. Someone could still vandalize the bit of wire and the female end of the connector I leave on the Vity but it hopefully will not stand out enough for that to happen.

3. Find a suitable DC connector to use. Had a look on the net - Wikipedia has a fair bit of info but there aren't really any other good resources on the net. I used sed what I could find on the net and in Maplin to do an analysis of my options, which is below.

Things I'm looking for in the connector

• Waterproof: The connection itself will not be protected from the elements, the connected wires will be in the front pocket of the scooter, so being waterproof is important.
• Sex: Most connectors are male/female but hermaphrodite connectors are a big plus in my view as this increases flexibility with what you can connect to what when dealing with leads.
• Availability: I am sure the US military has the world's most advanced 12V DC connectors, but I need something available off-the-shelf in electrical or DIY shops for cheap.

Options for 12V DC connectors to connect my Garmin Zumo GPS to my Vity battery:

Spade terminal: Normally used to for DC connections in home projects. Downside is that the insulation is not very good (i.e. risk of shorts) and not even water resistant let alone waterproof. Big upside is that it can be crimped onto wire which saves the effort of soldering - I am a big fan of not having to solder if it can be helped.

Molex: Normally used in computers. Downsides are it is not waterproof and has two positive wires (12V and 5V), which is more than I need.

Tamiya: Normally used in remote controlled planes and cars. Downside is it is not waterproof. Otherwise is easily available and not too expensive.

Cigarette lighter: Normally used as a 12V output in cars. Downsides are that it is not waterproof and apparently does not stay well fastened on bumpy roads. Big upsides are that male and female leads are widely available and cheap as are other accessories such as car ipod chargers, car usb chargers and car 12V-230V invertors for running AC equipment.

SAE: Normally used for motorcycle accessories such as battery chargers (e.g. battery tender), heated gloves etc. Seems like an obvious choice given that other motorcycle accessory manufacturors must use it for a reason. Can't see any obvious downsides, though connector leads are expensive in the UK (though very cheap in the US). Massive upsides are that they are waterproof, hermaphrodite connectors (which means more flexibility since no separate male and female leads) and not too difficult to find on the interweb.

Conclusion is that SAE connector is the obvious choice, though I must also buy a SAE to cigarette output (female) converter (see below) since so many travel accessory options are available with cigarette lighter male leads (e.g. ipod charger and blackberry charger). This way I can charge my ipod or mobile when I don't have the Zumo hooked in.

First Published 30 January 2010