Thread: 1 alt 2 batt need isolator help

what?

Ive never done an isolater I always use the sr200 realy from stinger but they should all hook the same power in power out a ground post and a switched post. If you alt is 300 amp id run a 300 amp isolator. and if you insist on running optima batterys use a yellow top in the rear not a red top

ok but the sr200 isnt 300 amp can i strap 2 of them together to get 400 amps out of them and how would i go about doing that, because i know the 300 amp alt isnt putting out 300 amps but i wanna make sure im not going to run into problems in the future and also im going to but this batt in the back of my suburban is it going to be ok to run an 0g wire all the way back to the second wire, would that effect the charge?

Javy, seriously! You need to learn about punctuation! Let me give you another concept as well... We call it the "run on sentence". You are soon to achive the 2006 award!

When will your alternator produce 300 amps? Not at idle! Most of the time the alternator will be well below the stated rating. Secondly, why do you need an isolator? Do you plan on playing the system with the vehicle off? Are you trying to isolate the system batteries from the car battery to eliminate starting problems? Just dont play the system with the car off. If you are dead set on using an isolator, just make sure the amplifiers after the isolator do not draw more than its stated amperage. if it does, you will have to run 2. One to its own dedicated battery and amplifier. Talk about overkill!

0 gauge to the rear is fine, but you need to upgrade all grounds on the vehicle as well. Look into upgrading the "big 3".

May i also recommend some 3rd grade grammar books? www.grammarbook.com

Nope, you cant pair the relays together. I would stick with the isolator for an everyday car. The relay will rob the starting battery of power when the relay switches on. The only reason I brought it up was because that is what I'm most familiar with. The isolator does just what it says, it isolates both batterys from eachother so they dont pull from and work aginst each other.
Will is right you dont need a 300amp isolator the reason I used that in an example was because that was what you used, keepin it simple. You could use a 300amp isolator if you wish but it may not be needed, personaly I would use a 300amp but I like overkill and for upgrade possibilities even though you will never need that much. Add up the max current draw you have with everything running that will tell you what size you will need. And yes you should upgrade the big 3 to maximize the effect you are trying to get from adding the second battery.
Aron

I run two batteries with a very simple setup. I have a Interstate Battery under the trunk and inside the car I have an optima red top. I have the accessory wire from the stereo hooked into a little 20 amp car relay (the ones about an inch square) which then drives a larger 80amp relay. The relay connects the power wire from the alternator to the optima red top battery.

I then connected my car computer to the optima battery.

Now this type of connection works great, I don't know what anyone is saying about stealing power on start, when my computer starts, like in most cars, the accessory power gets turned off, this turns off the relay isolating the rear battery and car computer from the car's main electrical system.

You can also use a yellow top, but I got a red top because my buddy at advanced auto parts told me that they don't know what I use it for and if I kill it, they come with longer warrantees - and if I need a replacement, most advanced auto parts stores carry red tops in stock.

Now I'm not sure why you would need an isolator. The isolators that use diodes (and from my understanding, most do). Diodes will steal 1 to 1.5 v of your power (and turn it into heat). There is no advantage to using an isolator that I can see is that it's solid state and there are no moving parts, however, relays are pretty reliable.

One thing I like about my setup, is that if my Interstate battery ever dies, I can hot wire the 80amp relay closed and start off the red top in the back - not that I recomend doing it on a regular basis, but I've done it once in a pinch and it's nice to know it can be done.

Originally Posted by boomintrac

Nope, you cant pair the relays together. I would stick with the isolator for an everyday car. The relay will rob the starting battery of power when the relay switches on.

I don't understand how a relay turned off when the car starts robs any power??? how are you wiring this up?

The only reason I brought it up was because that is what I'm most familiar with. The isolator does just what it says, it isolates both batterys from eachother so they dont pull from and work aginst each other.

This depends on the isolator, but the major majority of isolators don't seperate the batteries from each other, it just keeps the secondary electrical system isolated from the primary system in a car. If you get a short in your secondary electrical system, it can end up causing your primary electrical system to be shorted out.

And yes you should upgrade the big 3 to maximize the effect you are trying to get from adding the second battery.

Yes, upgrade those big 3!

how do you figure that he couldn't use a pair of relays? I've done it.

Is this the best setup to run for a higher power capacity?