how connect dual battery with switch

[cuenta]

This is the most common wire installation of a battery switch with 2 battery

 

[tpenfield]

Re: how connect dual battery with switch

Yes.

 

[cuenta]

Re: how connect dual battery with switch

my neighbor connect the ground to common
resulting in a short circuit

 

[hungupthespikes]

Re: how connect dual battery with switch

my neighbor connect the ground to common
resulting in a short circuit

Common mistake :facepalm:
Switch is toast most of the time after.

 

[cuenta]

Re: how connect dual battery with switch

fortunately not burn anything

 

[cr2k]

Re: how connect dual battery with switch

Best to get a "make before break" type switch. It can be switched with engine running. The common Perko Switch is this kind.
A switch that breaks connection before making the other one can fry your electrics and electronics if switched underway.
How when your engine is turning the alternator is producing current that goes to the system and battery if you add batt 2 before removing batt1 the current has somewhere to go. If you take batt 1 out of the loop without first connecting batt 2 the current will back feed and blow out your system.

 

[Silvertip]

Re: how connect dual battery with switch

Then there was something else mis-wired.

No there wasn't. BAT 1 terminal has +12 volts on it from battery #1. BAT 2 terminal has 12 volts on it from battery #2. Connecting ground from either or both batteries to the COM terminal on the switch creates a dead short when either BAT 1, BAT 2 or BOTH are selected. COM is not ground on a dual battery switch. It is a label that has been poorly chosen by the switch manufacturer. In reality is the POSITIVE output of the switch which may consist of BAT 1, BAT 2, or BOTH. The only ground in this system is the negative terminals of the battery and the engine block.