• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

DUAL BATTERYS?

O

OZNAD

NAXJA Forum User
Location
pennsylvania
HOW HAS ANYONE ELSE SET UP DUAL BATTERYS WITH OR WITHOUT A KIT? MOSTLY I FIGURE I CAN PUT AN EXTRA BATTERY IN THE BACK OF MY JEEP WITH A CABLE, VOLTAGE REGULATOR?, AND A SWITCH TO DISCONNECT THE SECONDARY BATTERY WHEN I DONT NEED IT. BASICALLY HOOK INTO THE EXISTING BATTERY IN PARALLEL. I DONT REALLY WANT TO GIVE UP ANY SPACE UNDER THE HOOD. TELL ME WHAT YOU THINK...
 
First, I think you should hit the CAPS LOCK key again - calm down. All caps can be difficult to read...

Second, there's no reason it can't be done. You don't need a "voltage regulator" (that function is already provided by the charging circuit,) but an isolator is recommended.

Let me first ask this - why for do you want to run the second battery? As in, what's the intended purpose? Are you going to be running a lot of accessories, do you want it as a backup to your starting battery - what? This little factoid can drive a number of decisions, so it is important.
 
I kind of have the same question Jon, I'd like a second battery, but not sure if I need one. I dont have a lot of accessories, winch is the main draw, and taurus fan when idling and winching. Not to hijack but if you have a really good quality spiral cell or gell battery do you need a second one? I know in Petersens 4 wheel off road the ultimate jk build they did had a cummins diesel put into a new jk 4 door, and everyone said they would need a second batt for that big diesel but they worked it hard on the ultimate adventure all week and never had a need for it. I'd be interested in your opinion on this too Jon.
 
tkjeeper said:
I kind of have the same question Jon, I'd like a second battery, but not sure if I need one. I dont have a lot of accessories, winch is the main draw, and taurus fan when idling and winching. Not to hijack but if you have a really good quality spiral cell or gell battery do you need a second one? I know in Petersens 4 wheel off road the ultimate jk build they did had a cummins diesel put into a new jk 4 door, and everyone said they would need a second batt for that big diesel but they worked it hard on the ultimate adventure all week and never had a need for it. I'd be interested in your opinion on this too Jon.
Click to expand...

Unless you're getting stupid with electrical add-ons - or plan to - you don't really need to augment a good gel cell or AGM battery. If you've got an Optima or an Odyssey (or a good lead-acid "wet" cell battery,) you probably don't need it.

Diesels get two batteries mainly for cranking. Your XJ starter motor draws (as I recall - haven't tested one in a bit) about 150-160A while cranking the engine. Diesels? Up around 350-400A or more (higher compression.) Diesels usually have the two batteries in parallel so that current capacity is added together.

So, I honestly think that if you're not running things like fridges, inverters, power tools, 12V air, and the like with the engine OFF, you don't really need a second battery. Running it all with the engine ON? You'll want more alternator - so look into that instead.

It has a lot to do with intended use and conditions.
 
sorry bout the caps lock hah ha. but anyway, would you still need a switch for the second battery with an isolator inline? and that would be it, just run the cables to the battery. i'm thinking 2 batterys because the more things i turn on in my jeep the more the voltmeter keeps going down. really i just want to be sure i have the juice when im out in the boonies.. thanks
 
OZNAD said:
sorry bout the caps lock hah ha. but anyway, would you still need a switch for the second battery with an isolator inline? and that would be it, just run the cables to the battery. i'm thinking 2 batterys because the more things i turn on in my jeep the more the voltmeter keeps going down. really i just want to be sure i have the juice when im out in the boonies.. thanks
Click to expand...

There are two ways to do the isolator.

1) Use a solid-state isolator pack. They're supposed to be "smart," but they can get spendy in a hurry, and you have to wire them per instructions.

2) Use a constant-duty solenoid. They're not "smart" like solid-state packs, but they can be had in higher current ratings for a given price, and you have some more options in wiring them (Override OFF, Override ON, both overrides...) so you have some more flexibility in your setup. If you want to see how that's done, go to my site (link in sig,) and go to the "Instructions" page. I've got solenoid wiring instructions there in .pdf format that you can check out.

I do still need you to answer my question, tho - what are you trying to set this up for?
 
Just go for it, I use my extra battery to power my deck, amp and subs. (when I have them in the car) The amp draws 2000 watts so I kinda need the extra battery:listenmus

Anywho, I also use the battery for extra lights, and my winch, and the best part of having a dual battery setup is... you can jump yourself. All you need is a positive cable going from one battery to the other. I've done it a bunch of times.

Here are some pics of my battery setup.

The blue box is the isolator, I upgraded the lines coming from the alternator to 2 gauge. Along with any other power wire under the hood. All upgraded. As you can see the red wire goes from the isolator to the second battery.

IMG_4499.jpg

IMG_4498.jpg

IMG_4497.jpg

IMG_4496.jpg
 
I've been running a Duo setup for several years. I've seen several configurations, which all seem to work :). In my case, I run a Wrangler Northwest isolator. This allows 3 connection states.

1) Restrict draw to primary, while charging both.
2) Restrict draw to primary, totally removing secondary from circuit.
3) Draw and charge both.

Hope this helps..
 
but not sure if I need one.
===========================
If you find you need to stop and let you battery rebuild often before finishing a winch? Yes.
But remember this down time also let the wench cool. Not a bad thing.
If your battery gets very warm when pulling? Definitely yes.
A much larger battery may work for you (yellow top or alike) if your using a near stock or older battery now
Two batteries need some kind of isolation form the ALT or you will eat your alt up fast if you winch much.
Much winching or any very heavy load on the charging system will always shorten the ALT and battery(s) life some.
 
i need another fuse box for mine because i have a lot of accessories so i was wondering this same question. can i just run another cable from the positive terminal on my stock battery to the second one? this way i can just hook up the accessories to the second fuse block
 
OZNAD said:
sorry bout the caps lock hah ha. but anyway, would you still need a switch for the second battery with an isolator inline? and that would be it, just run the cables to the battery. i'm thinking 2 batterys because the more things i turn on in my jeep the more the voltmeter keeps going down. really i just want to be sure i have the juice when im out in the boonies.. thanks
Click to expand...

Have you upgraded your alternator yet? If your voltmeter is dropping while you've got the engine running, that means that your alternator isn't up to the task, and you're draining your battery (with the engine running, you should not be.) A little voltage drop is normal - it's simple maths - but as long as the alternator/system voltage stays above 13.0VDC with the engine running, you should be fine.

Note that you don't get full output from the alternator until about 1200-1300RPM at the crankshaft. If you're worried about charge, turn everything OFF and idle for about 5-10 minutes before you shut down to top off the battery.

I'm just worried you're offering up the wrong solution to the problem, and you could end up getting stuck anyhow. The issue may be generation capacity, not storage capacity.
 




What would happen if two hot leads were used?One for each battery comming from the alternator?Batteries not hooked together so one wouldn't drain the other.
How would the alternator react to this?

If this way doesn't break any laws of electricity you could simply hook one positive jumper cable from the secondary to the primary in the event that a self jump is needed.Or during winching???Then when the additional amps of the secondary batt. isn't needed,unhook the jumper and the secondary will stay charged because its always hooked up to the alternator.
Perhaps the alternator would be confused by the voltage of the primary and send too much voltage to the secondary?
Maybe I have to look further into how the alternator "sense lead" works.Is it possible that the secondary battery will get over charged due to feedback the alternator is receiving from the primary(I.E the primary batt is low so the alt sends juice to it,the secondary is full but it receives juice regardless because both batteries are hooked up to the same alternator output)?
Damn I think I had too much coffee........sorry if I confused anyone.Maybe what I am thinking about requires an alternator with two separate regulators(if that even exists,IDK)
Feel free tell me I'm stupid.......
 
Last edited:
Here's what my 1st version looked like. I've since made minor updates, but overall this is my setup.

Pict0093_sm.jpg


Pict0091_sm.jpg


This shows the 3 LED states of the isolator.
Battery_Mgr_switch_sm.jpg
 
outlander said:




What would happen if two hot leads were used?One for each battery comming from the alternator?Batteries not hooked together so one wouldn't drain the other.
How would the alternator react to this?

If this way doesn't break any laws of electricity you could simply hook one positive jumper cable from the secondary to the primary in the event that a self jump is needed.Or during winching???Then when the additional amps of the secondary batt. isn't needed,unhook the jumper and the secondary will stay charged because its always hooked up to the alternator.
Perhaps the alternator would be confused by the voltage of the primary and send too much voltage to the secondary?
Maybe I have to look further into how the alternator "sense lead" works.Is it possible that the secondary battery will get over charged due to feedback the alternator is receiving from the primary(I.E the primary batt is low so the alt sends juice to it,the secondary is full but it receives juice regardless because both batteries are hooked up to the same alternator output)?
Damn I think I had too much coffee........sorry if I confused anyone.Maybe what I am thinking about requires an alternator with two separate regulators(if that even exists,IDK)
Feel free tell me I'm stupid.......
Click to expand...

Electrically, they're still connected all the time. No isolation exists (the electrical connection is still in common at the alternator.)

The reason for isolation is so that accessories may be driven off of one battery while the engine is OFF without disturbing the starting battery.

The alternator will generate whatever current the regulator thinks the system needs (up to the capacity of the alternator,) regardless of the individual state of charge of the batteries. If the regulator decides that 45A will supply all the electrical needs at the time, that's what you get. If it decides that more is required, it will allow more to be generated (again, up to the maximum capacity of the alternator - usually the rated capacity -5%/+10% or so.)
 
xj4fun said:
Here's what my 1st version looked like. I've since made minor updates, but overall this is my setup.

Pict0093_sm.jpg


Pict0091_sm.jpg


This shows the 3 LED states of the isolator.
Battery_Mgr_switch_sm.jpg
Click to expand...


More info on the isolator and LED switch used for your setup please.....Where did you get them at?
So in dual off mode the aux battery isn't being charged?Is dual off the mode you run in under normal driving circumstances?
 
Last edited:
You must log in or register to reply here.

Similar threads

S
98 A/C resurrection
Replies
15
Views
3K
XJlimitedx99
X
S
98 XJ manual ignition problem
2
Replies
20
Views
4K
SurplusFan98
S
Saudade
Speedo Deado
Replies
4
Views
2K
Anak
Anak
M
Re: Battery, alternator, voltage regulator?
Replies
0
Views
11
melanmack
M
M
1992 XJ A/C Air Conditioning Replacement - Parts List
Replies
7
Views
2K
Rob Mayercik
R
Back
Top