2 Batteries

[crazy2287]

Sorry dude, unless you own a plastic car, ie: v12 Corvett ect then your car body is just a big chunk of metal. Replacing the big chunk of metal with a big round chunk in the shape of a wire is not gonna do jack.
You need 1, suitably sized wire going to the chassis, terminated correctly. and 1 going to the engine block, terminated correctly. Good quality terminals, wires and terminations are your friend.
Incorrectly terminated earths can cause a voltage with reference to the battery's earth to build up at the junction of the termination. This will cause feedback to any device terminated to the same point, as it will not be seeing true earth and current oscillations can occur. but that's neither here nor there.

If you seriously think you have a huge current demand in your car then just go into the shop and ask for a meter of red and a meter of black zero awg cable. use it for alternator to battery positive, and battery neg to chassis and engine bock.

[quangsuke]

this might be noob, but can someone explain this to me?

so OP wants to use a second battery to power his amp etc?

can't he just run a line from the negative cable from the CAR BATTERY to the second battery's NEGATIVE?

then from the second battery's positive to the amp to run it?
obviously the amp would be grounded aswell.

just connect a switch and fuse from second battery to amp so u dont drain the second battery.
if im wrong please explain.

[crazy2287]

no.
the process you have describes is called series hookup, This sill cause the amp to be provided with 24+ volts. definitely a bad idea.
also the battery will never charge in this condition as the alternator would need to provide over 24V

the battery needs to be hooked in parallel (positive to positive) to increase the amp hours available not the voltage. In this case.

[quangsuke]

now that makes more sense.

[crazy2287]

Sorry, I miss read your post. You kinda have the right idea. But your diagram dose not correctly reflect what you posted. in the diagram the total potential that the amp would receive is zero volts. (there may be a tiny voltage but that would just be caused by the difference in the native voltage of the battery's.

In your actual description your half way there, you also need to connect the battery's positives together. Then they will be configured in parallel. Otherwise only 1 battery at a time would drain, without connecting positives the battery's will be isolated from one another.

[grifty]

why not just buy one of them dual battery kits?

[slimx]

Sorry dude, unless you own a plastic car, ie: v12 Corvett ect then your car body is just a big chunk of metal. Replacing the big chunk of metal with a big round chunk in the shape of a wire is not gonna do jack.
You need 1, suitably sized wire going to the chassis, terminated correctly. and 1 going to the engine block, terminated correctly. Good quality terminals, wires and terminations are your friend.
Incorrectly terminated earths can cause a voltage with reference to the battery's earth to build up at the junction of the termination. This will cause feedback to any device terminated to the same point, as it will not be seeing true earth and current oscillations can occur. but that's neither here nor there.

If you seriously think you have a huge current demand in your car then just go into the shop and ask for a meter of red and a meter of black zero awg cable. use it for alternator to battery positive, and battery neg to chassis and engine bock.

I dno mate.. but it works now so yeh. lol
Now i gota beautiful earth going through the metal lol before i dno lyk it was just shit weak? or i dno fk it was fkd

I fixed the issue, thats what matters just earthed the battery. that did the trick

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why not just buy one of them dual battery kits?

I googled around about that. i didnt quite get how it works n shit.. i hate using kits and shit. i tend to like wiring shit up myself. I gave up on the 2nd battery n gave it 2 a friend nyway so this thread can be CLOSED