Thread: Can bad ground drain the battery?

A bad ground causes a resistance in the circuit which could affect battery charging.

The whining noise could be an earth loop. Ideally all audio components should be earthed to the same point. Suggest you clean all earth points

I think I know why I am getting ground problem.

The 600Watt amp, which is under the driver's seat, has its ground wire (8AWG) running back to the dash board area where it is connected to a distributor block, then is terminated on one of the chassis bracket.

the 8 AWG ground wire is about 4 feet run - from the drivers seat to the dashboard (right next to the steering colume joint) that's way too long.

I should get the wire directly terminating near the seat bracket area.

Correct?

Then where should I be terminating my Headunits at?

dude.., i had the same problem on my old civic about 2 weeks ago. the battery would die after a couple of hours after jumpin it and a new battery would only last about a week before it needed its first jump. after about a week in a Honda shop a new alternator (which was only about a year old), 2 new batteries, and 300 bucks in shop costs, the problem was........ my after market alarm system. and that was a real shock cuz i really thought my sound system was the culprit. it really could be anything, so the best thing to do is just drop it off at a local shop and let them run a full diagnostic on it and save yourself alont of time, money and heartache.

You should still ground everything to the same spot probably. I think 8awg might be too small a guage of wire. Why not just buy another 4awg 4' wire? That's what I'm running on my 600w amp going back at least 10' with no problems.

Where should I ground the head unit?

I've got two headunits - One is 7" monitor DVD player, the other one is HDD based Divx/MP3 player. Both are taking its power from the stock OEM power line.

How much does the RCA interconnect affect ground loop? (Alternator Whine) I've got a "Diesel Audio" interconnect that is about 3 feet longer than what I really need.

I grounded my amplifier with a short (about 10 inch) 4AWG wire, directly to the chassis screw under the seat.

It reduced the alternator whine, but it is still there. I can hear it.

So, all of you experts outthere...

If you have two headunits and one 600watt amp under the seat, how would you wire everything up?

In a perfect world, everything would get it's power and ground from the same point and we'd all be on our merry way It's better to have everything grounded to the same distribution block, rather than an amp be grounded in one spot, and the deck another (I'm off today, and bored, so I'll offer a short explanation as to why at the bottom of the post, if you're interested ). 8 Gauge is a little small for 600W, and I'd jump up to 4 Gauge and ground everything to the same block. Everything.

Turn on your car and measure the voltages between your power and grounds at the battery, Amplifiers, the Deck, and the Computer. If there's a difference of about 1/2 volt or more, you'll most likely induce noise into the system.

Usually the noise is going to get introduced between the deck and the amp. If you mute the radio and the noise is still there, that's whats happening. An easy way to minimize this is to lower the gain of your amplifier, and raise output of your stereo. Turn the amplifier all the way down, then crank the deck almost to max volume. Then, turn your amplifier up to your maximum listening volume. By doing this, you're minimizing how much the noise gets amplified.

Also, some AC current stays in your car's power system, so be sure not to run your RCA cables next to your power/ground wires or you'll induce noise into the system.


Hope it helps.


*A quick simple partial explanation for everything being grounded to the same point. One grounding point might have a few more Ohms of resistance in the circuit than the other one, which makes current flow it's own little circuit, in a loop from say the amplifier ground, through the chassis to the Radio ground, and back through the RCA plugs and it causes a hum, and that's called a Ground Loop. It's much more common in fixed system such as your house than your cars, but it does happen.
The reason is you're simply running the power and RCA lines too close to one another.

Here is a loose guide for power requirements vs cable

Power Wire Gauge Guide
Total Power 15 Ft 17 Ft 20 Ft 22 Ft 25 Ft
100 Watts 10 10 10 10 8
200 Watts 8 8 8 8 8
300 Watts 8 4 or 8 4 or 8 4 or 8 4 or 8
400 Watts 4 or 8 4 4 4 4
500 Watts 4 4 2 or 4 2 or 4 2 or 4
600 Watts 4 2 or 4 2 2 2
700 Watts 4 2 or 4 2 2 2 or 1/0
800 Watts 2 or 4 2 2 2 or 1/0 1/0
900 Watts 2 2 or 1/0 1/0 1/0
1000 Watts 2 2 1/0 1/0 1/0

All wires in AWG