Evening All,
I'm fitting a second battery at the weekend and am wondering what size cable I need for the connection between the 2 batteries. Not intending to run winch type eqipment, just a worklamp, aux power socket for portable fridge.
Already got 1 split charge fitted for the Caravan and the cable for that is not particularly heavy duty. Would a length of th do the job or should I be looking at battery cable?

Many Thanks

Gary

If you are connecting the batteries using a split charge device then use the cable in the kit. If you are just linking them in parallel then you will need starter cable.

It depends how far the battery is from the charging point. If it is in the engine bay then use normal battery cable at least so that the battery does charge. If it is further away use thicker cable up 35mm sq to prevent voltage drop.
It is a concern that you have thin cable to your caravan - check the voltage at the caravan battery with vehicle running and make sure it is enough to charge the battery +13.4 volts. If you don’t use adequate thickness cable you will not fully charge any of your auxiliary batteries. Don’t forget inline fuses.
For the auxiliary point wiring you can use thinner wire to make connections – don’t forget inline fuses.

You can charge a car battery on a 1mm cable, ie just like a small battery charger uses, the question is what cable to use when drawing or supplying a current. Forget voltage drop, 12 volts going through a 50 metres of thin alarm cable will still be 12 volts at the end.

If you intend to install two batteries in parallel the use the same grade of cable that is used for connecting the existing battery (as stated by landmannnn above) the link below shows the common grades available.

http://www.vehicle-wiring-products.eu/VWP-...atterycable.php