New Member, and Couple of Newb Questions!Battery Questions,Amp Connections!?

[aguita 10+ year member]

hi, im new here and basically new to the sound system world..

currently I have 2 amps , 1 audiopipe 1500.1D and a JBL 1000.1, I have done the Big 3 and im running 4ga wire, I have 2 batteries installed today and I noticed something weird..

the store that made the installation installed a brand new interstate 800cca for the main battery since my old battery was weak,and a second AGM 755cca Deep cycle SP power battery as a second battery.

I was reading on how should this batteries be connected and came the parrallel, they are connected in parallel but I noticed that the installer put the 2 batt NEG- wire to the frame of the car not the the first (interstate) NEG- post, he did the POS+ of the second battery to the Interstate.

Is this a good way or i should connect the NEG- of the second Battery to the NEG- of the Interstate?

also, I noticed that after installing the second battery I have a CAP on the back and it showed 13.8v on idle not playing, and now after the second battery im looking 12.8v -13.1v not playing, this doesnt sounds good to me, I asked the installer why is this happening and he told me so BS that the Second battery had to be charged,thats why I was looking that voltage till the battery gets charged.

also I noticed also that both amps are grounded to bolts on the rear of the car and I was reading on a thread that they must be grounded to the battery itself!

So my concern is, should I connect both amps POS+/NEG- to each battery post directly? to which Battery?

also should I add a isolator? I will use the system mostly with the car off, If I should add a Isolator which cap I should buy?80amp,200,500 etc?

thanks in advance!

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[aguita 10+ year member]

no one?!

 

[Louisiana_CRX 5,000+ posts]

It depends if your vehicle is a uni body or not...If its old school and has a frame a bolt in the rear will be fine...though I usually drop to frame and beef the stock battery ground up and run to frame to acheive the lowest resistance

 

[aguita 10+ year member]

thanks for the reply, i have a 08 Toyota 4runner, what about the way that the batteries are connected? thanks

 

[All_Logix 10+ year member]

With the addition of the second battery the electrical system is going to need to charge it as well as run all of the other electronics for a bit. The difference in voltage is most likely do to the fact that there is now an extra load on the system that has to be accounted for if the batteries are not fully charged. As for how it is grounded, I think you are fine having it grounded to the frame, if you want to run the negative post on the secondary battery back to the primary neg post, it cant hurt. I have seen people ground at both the chassis and the negative post on the primary.

 

[audiolife 5,000+ posts]

Best ground is grounding to alternator case via the alt bracket.