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i want to install another battery in my car i have everything i need to do it just need to double check to make sure it's hooked up right.

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if it's big it's ok, if it's shinny it's better. if it's loud, it kicks. the louder the better

make sure the 2 batts match....ive had problems with the charging systems not charging 1 batt fully if they didnt match. something to look for. and dont forget to fuse the rear batt also. XS

You should use a PAC-200 Relay to isolate the batteries from each other.

Can you list the items you have for this 2 battery setup? just to make sure you got everything. There really isnt much. Your alternator should produce enough amps to charge both batteries. I am not sure why people say the batteries should be identical, I don't think they need to be identical.

I am in a similar predicament whereby I purchased all the items I think I need. Just need to hook it up.

Also like mentionned above, make sure you have a isolator relay and fuse for each battery. I put fuses for every device as well. Having extra fuses dont harm, but having too few is cause for burning up something.

mark

what happens if you hook up 2 new batteries to a 100amp alternator? that is all my stock nissan alternator puts out and i have a new red top and yellow top optima i want to install into my maxima?

what u need 2 batterries for?

t0mmyr, think if it this way. A battery is basically like a bank, where you keep putting $1 every millisesecond (the alternator storing some current to the extra-battery). Once in a whiles (each time your subwoofer is hitting a powerfuil bass note) you need more power whereby the current is being provided from the extra battery. Like withdrawing $100 from the bank. Even though you are withdrawing $100, it is still nothing compared to what you saved by adding $1 every millisecond. Now havin 2 batteries would be like having 2 banks. You will surely be putting little bit of power in each battery, but I havent seen anyone yet with 2 batteries. Are you sure you need 2? What made you decide on 2 batteries? That might give us clues. Also what power amps and speakers are you using? I am sorry if I bored you with the bank analogy, but I just thought it might be helpful for some.

Mark

the bank analogy is good, easy to understand this way. i had a red top optima battery already, and i just got it replaced for a brand new one, and i was also given a yellow top battery brand new, so i might as well as use them, when i had my system installed in my old truck i used to get the lights to dim with 2 caps installed, so i'm hoping 2 batteries will alleviate this problem, i'm running a JBL BP1200.1 amp for my sub which draws max 120amps, https://www.jbl.com/car/products/product_detail.aspx?prod=BP1200.1

and a Polk Momo C400.4 for my 4 component speakers which draws 60amps

https://www.polkaudio.com/caraudio/specs/amps/c400_4/

theyre both power hungry

A extra batt only helps if you plan on playing your system with the motor off. It will let you play longer. that's it. It will not make a bit of differance if your car is running. That is when your alt is powering your system. and charging both batts. Make sure you have a ho alt. (extra batt=extra load) start with 2 new identical batts. I don't use isolators myself. Some one is sure to argue that with me. I have been running dual batts for years never had a isolator, no troubles.

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Big Dave

i just join up today and what i seen so far this is a good site any way i need help

got citroen ax gt the alt is 50/70 and the ice system i running is,

jbl 1100 watt

2 x 500 watt subs

and all speakers

how do i install a 2 battery

PAC-200 Relay any links.......?

ya thats what i wanna know. can sum 1 tell us how to install a second battery?

just found this yes or no......?

[img]https://www.kampenwagen.co.uk/images/Split_charge_relay.gif[/img]

[QUOTE=axandy]

just found this yes or nohttps://www.kampenwagen.co.uk/images/Split_charge_relay.gif[

the only time you dont need to isolate 2 batteries is when you are running 2 identical batteries...........you are going run a red top and yellow top, you do need to isolate them from eachother as they are completly different batteries.

to be honest with you, you dont need 2 batteries. your mono amp has a 120 amp fuse in it but i will guarentee it doesnt draw 120 amps...and the 4ch amp will not draw 60 amps either .......if you want to eliminate the dimming headlights invest in a 200 - 300 amp alt...

try selectproducts.com

axandy wrote:

PAC-200 Relay any links.......?

You actually want to use to batteries if you see yourself playing your system with the car not running. You isolate your entire system with one battery and have the other battery so that you can start your car without worrying if you've played your system too long. Once the car is started and running, the relay or isolator will charge both batteries at the same time.

suicidecustom wrote:

the only time you dont need to isolate 2 batteries is when you are running 2 identical batteries...........you are going run a red top and yellow top, you do need to isolate them from eachother as they are completly different batteries.
to be honest with you, you dont need 2 batteries. your mono amp has a 120 amp fuse in it but i will guarentee it doesnt draw 120 amps...and the 4ch amp will not draw 60 amps either .......if you want to eliminate the dimming headlights invest in a 200 - 300 amp alt...

First off is your alternator able to handle the second battery. If you are doing this to reduce headlight dimming this will make it worse. Second is the battery you are going to be using identicle to the old one. If it is you will not need an isolator if it is you will need an isolator. To install a battery without the need of an isolator you will need to run a high gauge wire(I would use a 2 gauge) from the alternator's positive terminal. Place a fuse that can handle the amps within 6 inches of bolth batteries( One next to the old and one next to the new) and then just ground the negative terminal(Make it the same gauge as the wire used for the positive cable). Take in mind this process should only be used with two i denticle batteriers, if they are not a battery isolator is needed. And you can pick up an insolator at your local car electronics shop or they can order it for you.

There really isn't much installing a second battery. Most probably you are installing a battery not identical to the original one in the vehicle. Whether the batteries are identical or not, adding an isolator just makes sure the two batteries don't "compete" against each other by draining off the one with more charge when your engine is not running (when your alternator is not charging). An isolator is just a high amp relay switch. Generally I've heard of (and myself used) a PAC200 isolator, which is a 200Amp relay. Just by looking at it, one can see 2 small connectors and 2 big connectors. The big ones connect the source or main battery's positive or the alternator's +ve to the extra battery's +ve. The relay (as any other relay), has 2 connectors, one of which connects to the ground(-ve) and the other to a +ve that is true ignition, meaning no voltage when the vehicle is not running.

Maybe a simple picture will help.. Let me draw up one. and post it in a few minutes.

The new battery's -ve goes to ground.. just in case someone has a question. Sorry about a not so great picture but just to show how easy the connections are. Also I made the switch's connectors thicker and the coil with thin lines.

Mark