Dual batteries and earthing accessories

[mnemonix]

In my current vehicle with a single battery (Optima D34), I would earth everything to a common earth on the chassis where practical.
Only items with heavy current draw (ie: winch) have both power and earth running directly to the battery.

I am now in the process of adding a Traxide SC80 isolator, with an additional pair of D34's in parallel under the tray specifically for running accessories.
The main battery will be reserved strictly for cranking.

The new auxillary pair will run all other accessories.
Warn winch, 400w of britax xray vision spotlights, rocklights, waeco cf-50dz, canopy/camp touring lights etc.

This whole creation will be fed by a 110a alternator (falcon).
Q's:
- Does anyone see any potential issues with this setup?
- Should I make up a pair of distribution blocks for both power and earth, and earth all accessories directly to the auxillary batteries.

[drivesafe]

Hi mnemonix, what is your reason for connecting your winch, driving lights and your rock lights to your auxiliary batteries?

[mnemonix]

No solid reasoning other than to leave the cranking battery for that sole purpose.
Quite flexible on the whole setup given a reason to do it differently.

[drivesafe]

Hi mnemonix, best practice is to have any accessories operating while the motor is running, to be connected to the the cranking battery and all accessories operating while the motor is off, be connected to the auxiliary battery.

With winch operations, as it’s imperative to get as high a voltage as possible while using the winch and one way to increase the voltage to the winch is to keep the cable run between the alternator and winch.

In most cases the shortest cable route is from the alternator to the cranking battery and then to the winch.

As the motor is running while winching, have a low cranking battery, caused by the winching operation is not a problem because you can simply let the motor idle for some time after winching is finished to allow the cranking battery to get some charge back into it before turning the motor off.

Furthermore there are some major advantages in using the cranking battery and auxiliary batteries together while winching.

The shortest cable distance from your alternator to your lights also applies.

[mnemonix]

Very informative post. Thanks for the info.