the biggest thing you could do before adding a second battery is add additional grounds -
from battery to frame, from engine to frame.
we all add nice thick power wires for our amps on the positive side- but electricity travels in a circle (in bascic terms) and forget about the ground -
I have fixed many problems with customers cars that outher shops could not figure out just by adding a 4 gauge ground wires. (can eleminate engine noise, dimming headlights) and make all electrical devices in car work easier.

 

GOOD CALL. Almost forgot all about that. hehe, I'll probably add an 0 naught gauge ground (battery to chasis), and couple engine to chasis 4 gauge grounds, when I start my next amp install. Good Info like this reminds me why I really like this board.

 

Isolators are made up of several high current diodes which restrict each battery from charging the other and eventually draining both batteries. The diode voltage drop is between .4 and .6 volts - not 2 volts! The isolators on my solar power system run at 13.7v between 4 optima marine batteries.

If the relay is opened and the alternator is not operational then both batteries will drain each others voltage as where an isolator can operate whether or not the alternator is running..

 

What extra wiring? I usually use the existing amplifier wiring kit to supply the rear battery *edit* I kinda trailed off here* Even an 4ga kit will work fine for the rear supply because the battery will supply most of hte peak demand.

 

Hmm, interesting... my research sux then... lol, as for extra wiring, I was thinking of the wiring needed to hook up an isolator or relay under the hood.

I was considering doing incoporating a solor trickle charger / relay so when I'm not using my car, my battery is always topped off

Good info.

 

The isolator can be installed where you already have the fuse for your existing amp kit. The alternator wire simply needs to be cut from the battery post and ran to the isolator - usually you can use wire you already have. definitely upgrade the alt to isolator wire to 4ga as mentioned above... and of course your other ground wires too. And I recently discovered that the alternator usually does not have a clean gound to the chasis either! so when adding another battery you might want to run a supply wire directly from a bolt holding the alternator to the chasis as well. I noticed an improvement in charging when I did this on my car.

*edit* the reason there is no stock alt to ground wire is because it introduces some level of noise into the electrical system which as the alternator ages will become more noticable. all cars have a starter to ground wire but it is usually isolated from the primary ground. My wifes honda accord has a alt to chasis ground wire but its really tiny =/

any connection with a direct +12v hookup will do for the trickle charger. I know some dealerships use the cigarette lighter with a solar panel to maintain the charge on new vehicles before they are sold. (imagine how embarrasing it is for a saleman to try to crank a new car only to have the battery be dead hahahaha)

I actually got to keep mine when I bought my grand prix and I still have it somewhere. just remember not to supply more than 13.6v if its going to be a constant charge(as in always on). anything over that will damage the battery once it reaches 100% capacity!

 

Are you saying the average person SHOULD upgrade / add a ground wire to the chassis for the alternator or hold off on that since it introduces noise into the electrical system. #1 thing that bugs the crap out of me (on my old systems) is the alt whine noise, I want to COMEPLETELY eliminate that on my next system.

 

yes i would upgrade your grounds - battery to chasis - chasis to engine

this should not ever induce noise into a system - but do the opposite -
try this measure the impedance from your battery - to chasis ground
now measure from amp ground to battery - the lower the number the better...

i have see great systems that can not get engine noise out of
i did this simple test and found a 10 ohm resistance in the ground (the cars factory ground was to a fender - fender bolts were loose..) i tightened bolts added a 1/0 gauge ground from battery to frame and then frame to engine block. all noise gone.
this car had been to 6 shops prior to me before i found it - it was a top isaca finisher that year....

 

^^ Pimpage ^^ - hehe, don't have nearly enough money to do Iasca style (too many rules), but deffinetely good pointers.

 

bad quality engine to ground wires can run into noise pros with adding an additional ground wire. If you do as Tirefly says and tighten(or better yet remove) the factory ground you can eliminate that risk. I do think that the Bat to ground and alt to bat should always be upgraded even if you arent running high draw equipment. My car starts faster and the lights dont dim when I roll the windows up etc...