what would happen if....

what would happen if i ran a wire straight from my alt thru a solonoid to a extra battery in my bed? alt to solenoid, to + on batt. - on batt to frame.and used this batt to run my comps and stereo... would this mess stuff up?

There are battery isolators made just for this purpose

Yup yup what he siad. Also you would be rolling the dice with having NO protection of anysort is there was a problem with the wire.

I wouldn't put the batteries in series like that unless they are both identical batteries (both model and age), otherwise they can fight against each other

And make sure you fuse the power wire run for the extra battery at both ends. I never see anyone do that correctly.

Y do you want to isolate the batteries? There is no need for any of that. Your alt on your vehicle puts our 100 amps? or close to it. It's strong enough to keep the battery under your hood and the other battery for your stereo charged. The batteries should be matched, same cca's. But it isn't really necessary. I had a crx one time with 2 12's pushing 1000 watts to each speaker. I put in a capasitor to handle the extra load. Not too long later the capasitor wore out and my headlights went back to dimming. I through a big truck battery in the back and just hooked it up parrallel to the battery that ran the car. I ran it like that for a few years and never had any problems. Never had to change any batteries or alternators.

You run an isolator because it seperates the charging and usage of each battery, Once again we have discussed before the importance of this, and also the worthlessness of capacitors under 20 farad. You need to run an isolator to have one battery running your engine electronics, one running your stereo.

Another rule of thumb, Your truck uses apox. 40% of your alt. max amp, So if its a 100 amp alt, your truck normally running will use 40 amps. So this way you can make sure your not WAY overloading your electrical stystem when using a stereo.