Need help installing a 2nd amp and trunk battery

[c_hayhurst 10+ year member]

^^

I originally had a 4 gauge power cable running from the engine battery to power my 50Wx4 amplifier for my front and rear stages.

Tonight, I ran a 1/0 gauge power cable to the trunk and intend on hooking that up to a trunk battery (Stinger, 300A) to hook up to an amp which will power my subs (amp and subs not yet installed). I wrapped up the end of the 1/0 gauge cable with electrical tape.

How do I properly wire the trunk battery and amp so I don't harm my car's electrical system?

Here is what I am planning on doing:

-attaching the 1/0 cable to the positive terminal of the trunk battery

-running 1/0 cable from the positive terminal of the trunk batter to the sub amp

-attaching a ground cable to the sub amp

-install subs

-listen to very loud music

Am I missing anything?

I am not anticipating doing anything with negative terminal of the trunk battery. Should I?

I am kinda flying blind here and cannot find a thread which can tell me what I should do,or any other website for that matter.

Click to read more...

 

[alvitae 10+ year member]

Find a good ground close to the trunk battery and ground the negative post there. Then a ground from that battery to the amp.

 

[thegreatestpenn 5,000+ posts]

I'm in town, if you need help hit me up. I have an extra batt in the trunk, its easy to do, but can be hell if you mess up

 

[DBBOOM 10+ year member]

Find a good ground close to the trunk battery and ground the negative post there. Then a ground from that battery to the amp.

x 2 Need to ground rear battery.

 

[c_hayhurst 10+ year member]

Find a good ground close to the trunk battery and ground the negative post there. Then a ground from that battery to the amp.

So, you are saying to:

1) run a ground cable from the negative terminal of the trunk battery to a ground, and

2) run a ground cable from the ground terminal of the amp to the same spot where I am grounding the battery.

Yes?

btw, should I install an inline fuse between the trunk battery and the amp? I already have one (one each) within 12" of the engine battery for both cables.

 

[alvitae 10+ year member]

So, you are saying to:
1) run a ground cable from the negative terminal of the trunk battery to a ground, and

2) run a ground cable from the ground terminal of the amp to the same spot where I am grounding the battery.

Yes?

btw, should I install an inline fuse between the trunk battery and the amp? I already have one (one each) within 12" of the engine battery for both cables.

No ground the amp to the negative terminal of the trunk battery. Yes, Put a fuse in between the battery and amp. It's a good idea to fuse the battery just before you get to it also. That way if something happens it doesn't head back to the front.

 

[c_hayhurst 10+ year member]

No ground the amp to the negative terminal of the trunk battery. Yes, Put a fuse in between the battery and amp. It's a good idea to fuse the battery just before you get to it also. That way if something happens it doesn't head back to the front.

To summarize:

1) run ground cable from the amp to the negative terminal of the trunk battery

2) run ground cable from the negative terminal of the trunk battery to a ground point

3) install an inline fuse between the trunk battery and the amp on the power cable, just in case, even though there is an inline fuse by the engine battery

Am I missing anything?

 

[alvitae 10+ year member]

pretty much good except for fuses. Always put one with in 18 inches of the battery. The engine battery is the main one actually.

And a third just before the trunk battery as power will be running both ways. If your wire melts it will stop at the battery instead of going back up towards the front. Arcing out and causing grief.

 

[c_hayhurst 10+ year member]

Here's a question:

I believe the trunk battery produces a DC current. As I understand it, DC currents flow from the negative terminal. If I run ground cable from the amp to the battery's negative terminal and then run cable from the negative terminal to the frame, wouldn't I be simultaneously:

a) running a current into the amp through the ground terminal

b) running a current into the car's frame

I am guessing that could be bad. Oh, so very bad.

 

[forbidden 10+ year member]

If you want to provide a charge to the second battery, it HAS to be grounded to either the frame OR the front battery. Car batteries are indeed DC. The amp does not draw current when it is off. Proper fusing protects the vehicle and equipment from damage. 3 fuses in total. One one power line from front battery (ideally within 18" of battery), 2nd on same power line at rear battery (this isolates the power line between the two batteries should there be a problem and should be within 18" of the second battery), the 3rd between the amp and the second back battery.

So, why are you installing a second battery? It does not produce current, it stores it only. If the stock electrical system is having trouble running the car and the audio system, adding a second battery is only going to make matters worse. The alternator runs the whole show in the car. If you are bound and determined to use a second battery, it had better be a gel cel type of battery and not a standard battery that produces gas....... that would not be a good thing on the inside of a car at all.

 

[c_hayhurst 10+ year member]

If you want to provide a charge to the second battery, it HAS to be grounded to either the frame OR the front battery. Car batteries are indeed DC. The amp does not draw current when it is off. Proper fusing protects the vehicle and equipment from damage. 3 fuses in total. One one power line from front battery (ideally within 18" of battery), 2nd on same power line at rear battery (this isolates the power line between the two batteries should there be a problem and should be within 18" of the second battery), the 3rd between the amp and the second back battery.
So, why are you installing a second battery? It does not produce current, it stores it only. If the stock electrical system is having trouble running the car and the audio system, adding a second battery is only going to make matters worse. The alternator runs the whole show in the car. If you are bound and determined to use a second battery, it had better be a gel cel type of battery and not a standard battery that produces gas....... that would not be a good thing on the inside of a car at all.

Thanks for the info!

It is a glass-packed Stinger 300A battery. I am running 1450W RMS (4x50W on 4-Ohm load, 1x1200W on 2-Ohm load), total as a daily driver and don't want to kill my engine battery. I only run the stereo loud for a few minutes at a time, maybe 10 minutes total in a 30-minute highway drive, and turn it down to human levels other times.

Dang, now I need to get some more fuse holders. I just wanted to pop this amp in and play! This has become sooooo expensive.