trunk battery question..please help

[missionx96x]

ok right now i have an optima yellow top in my engine bay. my friend got me a bosch battery same size as my optima for free so im now gonna mount a second battery in my trunk. only reason i am doing this is because of the system i have in my car. now which battery should go in the trunk? the optima or the bosch? does it matter which is where?

 

[95blackGsTurbo]

I would just keep the Optima in the front and use the Bosch for your stereo. Is it going to be remote or are you going to be wiring them in Parellel?

 

[DGajre777]

You only need a second battery if you want more engine off playing time. Having 2 batteries will make the alternator work longer and harder since it has to charge two batteries.

If you want to put a battery in the trunk get a sealed battery that way gases don't emit from the battery. You could use the battery that your friend gave to you if you put it in a sealed box with a tube it in venting to the outside of the vehicle.

Why do you want a second battery anyway?

 

[missionx96x]

heres what the guy at the alternator place said. mount a battery in the trunk. run a positive from the alternator directly to the battery in the trunk. run an additional positive from the alternator directly to the battery in the front. ground the trunk battery to the body. same with the front obviously. and thats it. by the way im doing this becasue i have 1000 watt system and a few other electronics in the car. the alternator is rebuilt and puts over 100 amps.

 

[MNGSX]

I would use a isolator inline between the rear battery and the "charge" lead from the front..

Even if you drain the rear battery the front will not discharge and still will start the car.

 

[Lil Bit]

Try a power capacitor for the stereo system. I have had 2 12 inch Orions in a prefab box in my car for about 10 years with a Lightining power cap and I haven't had to replace the alternator yet. The power cap is like an extra battery for the stereo only. It doesn;t strain the alternator

 

[DGajre777]

Installing a second battery is like using a band-aid on a big audio system. Get a big alternator or downgrade your audio system. Another option is to get Class D amps that take up less power than regular Class AB amps.

A capacitor doesn't really do anything unless you have diming headlights. A cap is not a replacement for a small alternator. A second battery will cause a bigger strain on the alternator. The ONLY Time a second battery will be useful is if you shut your car off and you want your audio to run for 2 hours instead of 1 hour.

A 1000 RMS Watt amp that is Class D will have a 80 amp fuse (depending on make) and will take the same amount of juice as a 600 Watt Class AB amp. With the 80 amp fuse on the Class D amp, it will take about 30 amps of current from the alternator.

 

[Lil Bit]

Actually, yes the capacitor does help. Think, the whole reason the lights would be dimming would be because of strain on the alternator and/or weak battery. So, if installing a power capacitor "fixes" the dimming headlights then you no longer have strain on the alternator. I still suggest a power cap. Good luck.

 

[brute]

I don't know if you read the tiny post way back towards the beginning, but it would be a very good idea to get a battery that didn't emit gasses. Maybe you could put the Optima in the trunk and throw the free one in the engine bay. It isn't very safe to be running an unvented battery back there...

 

[DGajre777]

Actually, yes the capacitor does help. Think, the whole reason the lights would be dimming would be because of strain on the alternator and/or weak battery. So, if installing a power capacitor "fixes" the dimming headlights then you no longer have strain on the alternator. I still suggest a power cap. Good luck.

No, the lights don't dim because of strain on the alternator and/or weak battery. They dim because the alternator/battery is giving power to the amplifier during bass spikes/peaks instead of the headlights and other electrical equipment. Batteries are not built to charge and discharge as quick as capacitors.

The only way to reduce strain on an alternator is to downgrade the audio system. For example, you can't expect to run an amplifier with a 150 amp fuse on the stock alternator.