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Cheapest way to run dual batteries?

1447 Views 21 Replies 7 Participants Last post by  Robert97dodge
I was wandering what all will be needed to run dual batteries? Also would it be safe to have the second battery in a marine battery box in the tool box? I dont want to put it under the hood because there is enough {expletive} under the hood on the passenger side. Or I may put it under the tool box bolted to the bed. Also what do I need to make the charge just go one way or whatever you would call it? That way I could just my self off. The 2nd battery would be just for my stereo stuff, any more lights that I add and electric fans possibly.
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Robo, there is a kit from Painless. But what I did is bought a new batt. tray for a diesel from Dodge for $35.00, hooked up an isolater for $29.00 and was done! Everything is auto. and works great. This is the third time I've used this set up in 30yrs. just to run a winch and lights.
and thats it?????
yea i had to do it in my old car for the system i had. run an isolater and the first batt will charge the second batt and the alt will charge the first
On 2005-12-04 21:11, weaktruk wrote:
Robo, there is a kit from Painless. But what I did is bought a new batt. tray for a diesel from Dodge for $35.00, hooked up an isolater for $29.00 and was done! Everything is auto. and works great. This is the third time I've used this set up in 30yrs. just to run a winch and lights.

So I just mount my battery somewhere, run the wires from my originaly batter to a isolator and then to my new battery? THat is all I need to do? What size wire will I need to run to the battery? And where can I get this isolator?
On 2005-12-04 21:11, weaktruk wrote:
Robo, there is a kit from Painless. But what I did is bought a new batt. tray for a diesel from Dodge for $35.00, hooked up an isolater for $29.00 and was done! Everything is auto. and works great. This is the third time I've used this set up in 30yrs. just to run a winch and lights.

ALso I had planned on just getting the battery tray from a diesel but I dont think that I have the room on the passneger side. I already have the Rancho compressor for my shocks plus som other crap over there.
http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENTRY_ID:2009231/showCustom-0/p-2009231/N-111+600010093+0/c-10107

try that
Next question I may already have the answer but I just want to make sure. If you have a altenator that pumps out 130 amps then do you know if you need a isolator that is rated for more than 130 amps?
okay first off its not an "isolator" for 30 bucks but just a big relay :flipoff: i'd get an actual isolator, that's what i'm going to try and do on my setup.
What size wire will I need to run to the battery?

I would use 6 or 8 AWG, you could go smaller, but if your installing new wire, get some that will handle the load. I would install an inline fuse also.
i'd get some 4 gauge welding cable. its pretty cheap. ya, a 130 amp isolator is going to be like $100 or more. you don't absolutely need the isolator either. it will just drain both batteries if something is left on.
if you decide to go without the isolator, make sure you hook them up in parellel (sp?) and NOT in series. Accidentally sending 24v to your ignition system would fall nicely in the bad catagory.
On 2005-12-05 06:05, chizzle1 wrote:
if you decide to go without the isolator, make sure you hook them up in parellel (sp?) and NOT in series. Accidentally sending 24v to your ignition system would fall nicely in the bad catagory.


I found this diagram on how to wire it. Does this look ok? ALso I am looking at the 120 AMP isolator. That should be good right?

http://www.jcwhitney.com/autoparts/Product/showCustom-0/Pr-p_Product.CATENTRY_ID:2006119/c-10101/Nty-1/p-2006119/Ntx-mode+matchallpartial/N-10101/tf-Browse/s-10101/Ntk-AllTextSearchGroup?Ntt=battery%20isolator

[img=200x110]http://www.jcwhitney.com/wcsstore/jcwhitney/images/imagecache/10015357.gif[/img]
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Does this do the same thing as that isolator up there or is this different?

http://cgi.ebay.com/STINGER-SR80-HIGH-CURRENT-RELAY-ISOLATOR-4-DUAL-BATTERY_W0QQitemZ5834993350QQcategoryZ50552QQrdZ1QQcmdZViewItem

Here is another one for 200amp.

http://cgi.ebay.com/ebaymotors/STINGER-SR200-HIGHCURRENT-RELAY-ISOLATOR-4-DUAL-BATTERY_W0QQcmdZViewItemQQcategoryZ33574QQitemZ8018033447QQrdZ1
in laymans terms, all an "isolator" does is fool the charging system into thinking that it's one battery. benefits of this include decreased load on the charging system and more reserve power to run accessories.

about the wiring setup: as long as you run + to + and - to - (also called 'parellel') you will be fine. If you run + to - (called 'series') you will get 24v instead of 12.
On 2005-12-05 08:24, chizzle1 wrote:
in laymans terms, all an "isolator" does is fool the charging system into thinking that it's one battery. benefits of this include decreased load on the charging system and more reserve power to run accessories.

about the wiring setup: as long as you run + to + and - to - (also called 'parellel') you will be fine. If you run + to - (called 'series') you will get 24v instead of 12.

So you are saying just run the wires straight from my old battery to a second battery? If I do then both batteries could get drained if I have a problem with the alt or something like that right?
yes. big trucks use the same thing, they don't use isolators. we have 4 batteries, all in parallel, no relays or isolators. i think the isolator that you would need prevents original equipment drain. so the alt charges your batteries, but only the new one you put in goes to our winch, system, lights. this way if you use your winch like crazy, or leave off road lights on, it won't kill our original battery.
On 2005-12-05 08:37, BR wrote:
yes. big trucks use the same thing, they don't use isolators. we have 4 batteries, all in parallel, no relays or isolators. i think the isolator that you would need prevents original equipment drain. so the alt charges your batteries, but only the new one you put in goes to our winch, system, lights. this way if you use your winch like crazy, or leave off road lights on, it won't kill our original battery.

My second battery will be used for my electric fans which will be pulling 28 amps, my amps for my system, and any lights that I add. THat is all. I guess that I will pick up some 4 guage wire and run the wires. Would 4 guage wire that you use for amp work? I can get a real good hook up on that stuff. Also if I run a in-line fuse what size fuse do I need?
4 AWG should be fine...you gotta think about what load you are going to be puting to what accessory. For example, you don't need a 4 AWG wire running to a extra set of lights...BUT, it would be a good idea to run something like a 6 or 8 AWG to a winch.

As long as the wire you are using has a good solid insulator on it, it should work fine. You can pickup a in line fuse from most radio shack or electronic warehouses. Just sodder (sp?) or crimp inline with your hot lead. If you are putting the extra battery in an enclosed area, ensure that it's 1) sealed type battery, also known as 'gel cells', or 2) has adequate ventillation (sp?).
On 2005-12-05 10:02, chizzle1 wrote:
4 AWG should be fine...you gotta think about what load you are going to be puting to what accessory. For example, you don't need a 4 AWG wire running to a extra set of lights...BUT, it would be a good idea to run something like a 6 or 8 AWG to a winch.

As long as the wire you are using has a good solid insulator on it, it should work fine. You can pickup a in line fuse from most radio shack or electronic warehouses. Just sodder (sp?) or crimp inline with your hot lead. If you are putting the extra battery in an enclosed area, ensure that it's 1) sealed type battery, also known as 'gel cells', or 2) has adequate ventillation (sp?).

The battery will be a Optima red top battery. I am already running one right now. I will pick up some 4 guage wire to run to the new battery then. Also I will be running 4 guage wire to the amp and then I am not for sure what size the wire is to my fans because I dont have them yet. They just shipped out today. Also I was thinking about using in-line fuse like this. http://www.hifisoundconnection.com/Shop/Control/Product/fp/vpid/1332983/vpcsid/0/SFV/30046 That way I can just pull the fuse if for some reason I dont want power going to the second battery. ALso if I run that I can pull the fuse and if I am just listening to the radio with out the truck on and my subs drain the battery I will still have the main battery with a good charge to start the truck. I tryed finding the specs to see what kind of amparage the amp will be pulling but I cant it. It does have 2 40 amp fuses on it though. So should I run about a 60 amp fuse for a inline fuse??
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