2x8, batteries needed??? HELP!!!

[420Snowman]

I am getting ready to put a davemade 2x8 in my mobile and am adding a yellow top optima battery in the trunk, charging in parallel with the stock battery. The stock alternator is 160 amps, will this be enough to keep up with this box??


Snowman

[linx]

Answering on the other thread...

[genesbro]

Unless you plan on doing lots of talking with amp on and the engine off you don't need two batteries.

[420Snowman]

Even with a 2x8???

[jessejamesdallas]

The Amplifier itself can draw 180 amps max. (80 amp draw continuous) So if your alternator is only a 140 Amp, that wouldn't leave you much to run the car if you only had one battery....Plus you would probably fry the alternator with-in a week trying to keep up the demand of amps required to run everything with one battery.

[Tucker442]

Over the years I have had a few high draw amps in my mobiles and my experience has been to have both batteries under the hood connected with large battery cable like #2 or #0. It's best if both batteries are exactly the same cracking amps and design, I would not put an Optima in the trunk and a conventional battery under the hood, hooked together these batteries might make one or the other discharge unless you use a battery isolator like the kind used in motor homes, where the body batteries are seperate from the underhood battery but both sets charge from the single alt. There are a few different ways to do this and have it work very well. Just my 2 cents and my over 40 years of playing with radios experience. Good Luck

[420Snowman]

Well, thats a good point, I didnt thing they would discharge eachother. I do have a battery cut off switch, drag race style that I could put in line to "turn off" the secondary battery after its been charged by the alt and before shutting the car down. Would that do the trick?

Snowman

[drdx]

Negative on the race car battery cutoff. I ran one between 2 batteries on an 8 pill and it started smelling one day, like burned plastic. It was the black molded plastic one with the red key they sell all over the place. The one I had was rated for 300a but I think that is very short duration. Evidently my rear battery got low, increasing the draw via the cable and the switch was the weak link. I was using 1/0 welding cable so I then ripped that out and went direct with 2/0, and batteries the same type- red tops.

-drdx

[420Snowman]

I am just being sure about the hookup to make sure its OK to hook the negative from my second battery to the frame. Hook the positive to positive and the negative from the second battery to the frame? Leaving the "car" battery negative alone, correct?

Snowman

[drdx]

Yep, and some will do an extra braid ground on the starting battery. Keep the negative as short as possible. I also like to ground the chassis of the amp with wide brade to a close ground point, as in inches long, really short. In fact, I ran a wide piece of braid under the edge of the entire length of one side of the cover, sandwiching the braid between for maximum connection. It probably does nothing for me but it sounds and looks manly.

-drdx

[420Snowman]

Good deal, Mudduck told me to run a larger charge wire on the alternator also, I think that sounds like an ok idea to me, it makes sense for sure. I am going to get the cables tomorrow and do some running and installing tomorrow night, hopefully the one extra battery will be enough. I dont plan on keying a bunch at idle or with the car off, most will be done while cruising on the highway, or at least in town. The advantage I DO have is the manual tranny, so if I'm creeping in traffic in town I can shift down to bring the RPM up and that should help I would think.

Snowman

[drdx]

Well, since it is a Solstice(or is it a Sky), on the air, once folks figure out what you drive, you could say to those you're messing with: "Wow, this is awkward. I'm in a Solstice, but in reality when I'm keyed up, we're experiencing a a total eclipse or your signal."

-drdx

[420Snowman]

GOOD ONE DR!!! hahah, well, Its in and done!!! One extra battery is enough for now, it doesnt even dim the headlights under keyup. The voltage drop is very small and nothing gets hot, (cables, alt wire, etc.) I am dead keying about 3-400 now and swinging to about 800 and the audio is CRYSTAL clear! I appreciate all the help from everyone and I am very excited to step it up in the mobile!
Here are a few pics of the install in progress from last night and yes, the guy that had the Davemade before me tried to polish it, dumb idea! Its going to get painted to match the car soon, just wanted to get it talking first.

Snowman
[Please login or register to view this link]

[Please login or register to view this link]

[Please login or register to view this link]

[Please login or register to view this link]

[maters]

My 2 cents, I ran a 1x4 dave under the seat, fed by 2 8 gauge wires. Put 600-700 on the meter with no dimming ,etc.

Upgraded to a 2nd battery, 2 gauge welding cable from the alternator to the under hood battery and to the 2nd. 6 gauge to the amp.

700-900 and the rat shack meter but a drag on the charging system.

I really do not think the additional wattage helped as much as the amps.

Get a lot more comebacks. Better audio surely more than the ghost watts.