My 2004 f350 super duty 4x4 dually short box is used to pull horse trailers. As it is so hot here, we haven’t been hauling out as much. I want to put a disconnect on the batteries. Do I need 2 of the lil darlings? How would you go about doing this?

thanks
Zeke (Oregon)

 

You'll want a disconnect for each battery. This is always the case in diesel applications where both batteries are paralleled, with no isolation between them.

On the other hand, in gasoline applications, where an extra battery has been added, the need for one or two disconnects can be differ, depending on how the secondary battery was installed. Some gas application second batteries are relay activated in RUN only, and in that case, only the primary battery would need the disconnect, because if the primary battery is offline, than the continuous duty relay that brings the secondary battery online will not have any power to be energized. But if the secondary battery is powering loads independently of the ignition switch, in order to keep the primary battery from discharging to a no start condition, then once again, you'll need to have 2 disconnects, one for each battery.

On yet another hand, if you have a gasoline truck with only one battery, and by "2 of the lil darlings" you are asking about a disconnect on each lead, positive and negative, of a single battery, then no, you only need one disconnect, and that should be on the negative lead of the battery, at the battery itself.

Here are a couple of examples of quick disconnects, commonly available at wax and oil auto parts chain stores, mounted to the negative post of a battery. The copper knife type disconnect switch is rated for twice the current as the green **** handle screw type disconnect.

 

Thanks. Information that is unambiguous and complete. Great job