minty

iTrader: (1)

i'm struggling to make sure that i wire this correctly and am not making much sense.

i have a trickle charger that i want to connect to the 12v on the cigarette lighter in the car and earth too.

I want to wire it though, so that when the ignition is On, it breaks the connection between the trickle charger and the car in order to protect the alternator.

And then when the ignition is turned off, it connects the circuit again and the trickle charger supplys the circuit with a feed.


can i do this with a single relay or will i need more? and how can i wire this up ???

Thanks
Chris.

500

why not just unplug it when you start the car

minty

iTrader: (1)

Because that's far too easy....

and if i forget or drive off in a rush and its still connected it wil damage the alternator, so i want to make sure and be safe.

Chelspeed

The easiest way is with a five pin changeover relay. Example at Vehicle Wiring Products it's no 3, part number R20BC.

Wire it up so that when the ignition is on it pulls in the coil and disconnect the supply from the charger. To do this wire the coil with ignition live 12V to pin 85 and put pin 86 to an earth. Then connect your charger to the input, pin 30, and connect the supply to the cigarette lighter to the output pin which is connected when the relay is off. This is shown as pin 87 on the diagram but as pin 87 is normally the one connected when the relay is on this may be a mistake. ?I'd have expected pin 87 to be connect when energised and pin 87a ti be connect when de-energised. Best check it with a meter or test bulb after you've wired up the other 3 connections.