I know we've been through all this before, but I can't find the link,and I have a friend who needs to know if its safe to do.

Ian,
Tomtoms work ok on 6V. Dont know about others but even if they dont work I cant think you could do any damage by connecting to a lower than normal voltage ie 6V.

I've been using my Sat Nav for two years in our Ruby, with no problems. I put in an insulated accessory socket, out of site under dashboard so I could reverse the polarity to negative earth. Our ruby run on 6volts.

I have a Garmin one that is suitable for Motorbikes so it's waterproof....just as well seeing as I never use the hood. It works perfect in the Tourer which is 6V and it worked perfectly on the EuroTour '07. No need to jump your cars up to 12V for Sat Nav people as some work happily on 6V

Thank you all very much. Ian.

Ian, Can't resist the quaesion: might one be hinding behind the request on behalf of a 'friend'? Can't imagine your solar powered Navigator needs any additional charging! I have found occasional Nagavator unreliability if not correctly handled to be way of heating up the interior regardless of the weather. The following silence should be used to truly appreciate vintage vibrations.
Ross

Like Mel i just added a £2:99 insulated socket from maplins and happily charge my PDA and sat nav.

Hi Ross,
Really good to hear from you,but I have read and re-read your posting,several times to no great understanding other than I it would seem that you may be well into your second bottle of Long White Cloud.Best wishes to you all ,and hope to see you again one day.{pig flu' permitting!}

In Mel's reply he says: "I put in an insulated accessory socket, out of site under dashboard so I could reverse the polarity to negative earth."

I have a neg earth Ruby and a pos earth special. If I want to use the satnav (which is neg earth) in both, do I reverse the wiring of the socket in the pos earth car? Or do these sockets come with a polarity switch?

Nick,
The sockets do not have a polarity switch so yes you need to reverse the wiring in the special compared to the ruby.

The contact on the tip of the sat nav male connector is the +ve. You will need to work out which contact this corresponds to on the male accessory socket - usually it is the central one on the end.

Daveg

erm i don't think that's right, I may be confusing myself here (especialy as no-one else has lept forward). But, surely the point of an insulated accessory connector is to make it irrelevant which is earthed on the car, you are just providing a positive and negative terminal for the sat nav with a 6V voltage difference, if you reverse the positive and negative terminals on the connector then it just won't work, the positive, whether it is at earth or 6V needs to go to the tip...or am I missing something

Arrrgh! I am almost certain that electricity was invented for the specific purpose of making my brain hurt.

Is Andy correct that if the socket is insulated then whichever way it is wired the satnav will either work or not work - and most importantly that in a 'not work' scenario the unit will not be damaged by incorrect polarity?

I knew I should have kept my head down on this one!

Firstly in my last post for "male accessory socket" please read "female accessory socket"

The point about using an insulated socket is that it can be used on a car with either +ve or -ve earth. If you have a -ve earth car you can use an uninsulated socket without any problems.

There are two connections to be made to the accessory socket, as they always say disconnect the battery first:-

1) The easiest place for the first one is to use a ring connector (bit like a washer with a tag on it to which a wire is connected)and connect to a nearby bit of the bulkhead (firewall?) using an existing bolt. This will be the "bodywork" connection.

2)The next connection needs to go to the non-earthed side of the battery. There are many places where this can be picked up and you can use a permenantly live point or pick a connection that is only live when the ignition is on. To keep it simple and to cover as many cars as possible assume this connection is made to one of the two terminals on the back of the ammeter again using a ring connector. This will be the "ammeter" conection.

It doesnt matter to the sat nav which of the two ammeter connections you use - the difference will be that on one side the ammeter will show the current drawn by the sat nav on the other side it wont.

Connecting to the accessory socket:-

Case 1 Negative earth (Nicks Ruby)
The wire previously connected to the "ammeter" will go to the connector on the female accessory socket that connects to the pip on the end of the male sat nav connector when they are plugged together. This is the +ve connection to the sat nav.

The wire previously connected to the "bodywork" goes to the other connector on the accessory socket. This is the -ve connection to the sat nav.

Case 2 Positive earth (Nicks special)
The wire previously connected to the "bodywork" will go to the connector on the female accessory socket that connects to the pip on the end of the male sat nav connector when they are plugged together. This is the +ve connection to the sat nav.

The wire previously connected to the "ammeter" goes to the other connector on the accessory socket. This is the -ve connection to the sat nav.

This is what I meant when I said you would need to reverse the special wiring compared to the Ruby. If you compare the two cases you will see that the difference is that the "ammeter" and "bodywork" connections are reversed.

To complicate it further in both cases good modern practice would require the "ammeter" connection to be made using an inline fuse situated close to the ammeter.

It looks more complicated than it is when written down. If anyone is still unsure email me with a telephone number and I will talk you through it.

Daveg

Many thanks David. Your explanation cleared the brain-pain more quickly than aspirin!