A*B Dual battery Installation

Hi All,

I am asking these questions, as batteries are not my area of expertise

A friend has recently purchased a new petrol Pajero.

He got A*B to install a dual battery system, with a smart solenoid, and with all new 12v outlets wired to the aux battery.

The aux battery they supplied was a 80amp/hr excite.

He was having trouble with his waeco fridge, as it would show the error light after about 8hrs.

The same fridge worked fine for 3 days in my Patrol also running a dual battery setup

Taking the car back to A*B, they informed us that they had installed the new battery, and made this the cranking battery, and made the original car battery the aux battery.

When we asked why they did this they said it was standard for them to do this setup. (WTF)

After we explained that we thought it was stupid, and they need to be swapped over, so we could get the most use out of aux bigger battery. They did this for us at no charge, and no hassle.

The A*B person we dealt with was always curtious, so I can not fault them on this account.

My question is:

Is this normal proceedure for A*B to do this type of battery switch, or am I not understanding their logic?

Being such a big player in the 4x4 industry, I cant understand why they would make the small cranking battery the aux battery.

All advice appreciated

Thanks

TonyG