How to connect a 2nd battery?

I'm wondering how I would connect another battery so that the alternator powers both batteries? I want to hook up my amps to the separate battery. Are there any effects to stock alternator, or should a more powerful alternator be installed?

I would connect the back-up battery to the main battery in parallel (+ to + and - to -) with cables of the same diameter as those for the primary connectors on the main battery.

I would also start off with two new identical batteries and always replace them in pairs.

This system would not allow separate connections to the amps, but two batteries charging in parallel is the easy way for the added storage capacity. No switches or relays needed. The effect would be like you had a huge battery with twice the plate area. As long as your alternator light doesn't come on when you're idling, you don't need a higher capacity alternator. If you do need one, they are easy to come by.

Just remember, I am not an electrical engineer, so YMMV on this suggestion.

Yes, parallel would be the best (aka ONLY) way to hook this up. Of course, you will be increasing the amerage and power going through the wires 2 fold by doing this, and I dont know what that would do to the electrical system (possibly blow all the fuses) This is assuming you hook it in parallel with the other battery.

Of course, if you hooked the new battery in series with the alternator (aka on set of wires going from the alternator to the original battery, and the other going from the alternator to the new battery) But if you did this you would need a new alternator.

Obviously I don't want to blow my fuses and increase the electricity going through the wires, possibly damaging something. I think the best thing is to hook it up to the alternator. Probably the best thing for what I want to accomplish, which is have a separate battery for my sound system.

You wouldn't pull any more current through your fuses than you do now. You would only have more power available - longer time before you ran out of electricity to start your truck. Batterys only supply the current required by a device. There would be no change in the current requirements of anything in your vehicle, only the amps you are connecting would draw more current than what is originally in your vehicle. You need additional power capability to keep from draining your battery - thus the second battery.

If all you did was connect another battery to your original battery in parallel, then the alternator would charge both automatically. Like I said, all you would have to do is keep an eye on the voltage warning light in your car when you are idling. If it comes on, then you are pulling more current with your amp and car than your alternator can supply. Then it is time to get a higher-capacity alternator.

Brian R. is correct. He knows what he's taking about. If you really wanted to get fancy, you could hook up a battery isolator instead of a direct parallel connection. Since your second battery would only be used to power your sound system, you could get by using 10 gauge wiring instead of thick battery cables. That's how I wired my auxillary battery for a cabover camper I used to own. The auxillary battery powered the camper only for lights, water pump, stereo TV and radio. I used a starter type relay switch which kept the vehicle battery from being drained while the auxillary battery was being used.

The battery isolator is the best way to go. The wiring diagram for this set up is probably included in the isolator package you buy. The advantage to using two equal batteries is that you have a back-up battery for starting in that case. Only a short in one of the batteries would prevent you from starting.

Check out this link:
http://www.4crawler.com/4x4/CheapTricks/DualBatteries.shtml

Hey
Go with a second battery on an isolater switch and as far as the second battery, go with either the yellow top optima or the stinger. Running the two batteries in on the same wires in parrelel is garbage you will replace your alternator in a few weeks time.
Listen to me bro and the other guy who suggested isolater switch its the best way. i have done it in my truck and i have two kicker solobarics two amps and have 2 1fared caps and denso 140 amp alt. I have sat at a car show for an hour and have played the tar out of my system and that was with the truck off and it started right up!!!!!!!! :thumbsup:

"Running the two batteries in on the same wires in parrelel is garbage you will replace your alternator in a few weeks time."

Why would that be? Still running at the same voltage.

Check these guys out for both DB kits and higher output alt's
http://www.wranglernw.com/commerce/default.asp
You can also take your stock alternator to an alternator repair shop and they will rewind it for more current.