Installing 2nd Batt

[I Like Waffle]

I got a second batt today im gonna install under the hood. Its a redtop, i went and got terminals and everything already for it too. Ive got some RF 4 gauge to wire it in with. Heres what im thinking. Pos from alty to batt pos, and ground the batt to the chassis? Or should it be grounded directly to the other batt or what?

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[Dak446 10+ year member]

go pos to pos on batts, neg to chassis on secondary

 

[BushJ311 5,000+ posts]

go pos to pos on batts, neg to chassis on secondary

agree. exactly how i plan to add my 2nd

 

[AcidikBass20 10+ year member]

Id only ground 1 battery. pos to pos, neg to neg. that way it forms a circuit in the batteries and charges them both, otherwise that second battery wont get any power.

 

[Dak446 10+ year member]

mine do...

 

[I Like Waffle]

Yea i was thinking i should ground them directly to each other. Would it be fine though if i wired the pos of the second one right to the alt too though? Seems like thatd be better.

 

[thegreatestpenn 5,000+ posts]

not really. batt to batt is the way to go for the positive so that power flows from alt to batt to batt to amp.

 

[I Like Waffle]

Yea but in order to charge, the 2nd batt is gonna have to **** current through the 4 gauge that goes from the alt to the first bat, then through like a 5 ft run of 4 gauge to the 2nd batt, where as if it was wired straight to the alt it would be only like a 2 ft pos run to the 2nd batt. Or i could do a run from the alt and a batt to batt run as well.