Dual/Multiple battery systems [Archive] - JKowners.com : Jeep Wrangler JK Forum

: Dual/Multiple battery systems


MichaelW
09-11-2007, 12:22 PM
Ok I'm just starting to learn about dual/multiple battery systems.

I'd like to run one or two yellow top spiral cell type batteries inside the cab. I'm thinking two so I can have them for my welder. I'm also going to be adding a little trailer soon into the mix which may also have batteries that will need charging.

thought: Could the batteries be wired in series for a Ready Welder and still run off the isolator and charge the batteries?

So is it as simple as running an isolator unit to separate the batteries for charging? What if I want to run more than just one extra battery? Surely this is easy as it is done in RV's all the time.

Does anyone have any recommendations on systems or sources?

Thanks!

gcg
09-11-2007, 03:36 PM
I'm running a dual battery system in my XJ. I use two Optima yellow tops and have a diode isolater system. With it, the alternator charges both batteries in parallel but they cannot discharge through eachother. So, one can be run completely dead and the other will still be fully charged. The batteries operate separately, not in parallel.

It all sounds great but I've found that the yellow tops don't last very long in this situation. I replace one each year at about $200 each. Way expensive! I don't know for sure but I suspect this is because the charge sensing lead is attached to the junction of the two diodes, which is a diode drop away from the battery voltage. So, it is going to regulate that voltage during charging and the battery voltage will be lower (by a diode drop). The net of all that is that the batteries are being charged for most of their cycle at a voltage somewhat less than the "preferred voltage" and may end up suffering a bit as a result. As I mentioned, I'm not completely certain on this but it seems to make sense to me.

As an alternative, you might want to check out the Hellroaring Technologies products (www.hellroaring.com (http://www.hellroaring.com)). Funny name but their product seems to be a better approach. They use a different technology that has a smaller voltage drop across it. They have several different products that allow you to configure your batteries in many different ways.

If I decide to do a dual battery setup in my JK, I will be looking at them, too.

AndyR
09-29-2007, 11:58 AM
I had a dual yellow Optima (kilby tray with a Wrangler NW system), with a Premiere welder & Engle refer, 2/440, CB, GPS etc).

It's going to be hard to put two optimas in the engine bay of the JK - especially for those of us who have AiROCK an/or SPODS.

My spies tell me that Yawan Smith (Kodiak Industries & Premiere Power) has just put a dual setup in the Cal4wheel giveaway vehicle. Me'tinks I'll be giving him a call.

Andy

MichaelW
10-03-2007, 02:27 PM
Did you hear anymore Andy? I am curious as I am looking for a place for batteries. I would like to have two "spares" for my welder that could be somewhat handy and am thinking of under the rear seat with some gel cells.

usmcdoc14
10-04-2007, 04:01 PM
I am running a Hellroaring system in my amigo and will be getting another for the JK (dual bats where the old muffler was :D )
pricey, but fawking sweet

MichaelW
10-04-2007, 04:16 PM
Thanks Doc!

I thought about that. Hmm.

Yep the HellRoaring stuff looks top notch!

Welcome to the forum.

usmcdoc14
10-04-2007, 05:26 PM
Thanks Doc!

I thought about that. Hmm.

Yep the HellRoaring stuff looks top notch!

Welcome to the forum.

dude it fully kicks ass, search pirate for "hellroaring" and I think I did a writeup.

That space under the "trunk" is perfect for 2 optimas side by side. I am going to cut a "cradle" that fits the "6 pack" of the side of them.

Quadratec, Inc.
11-14-2007, 10:31 AM
Optima's dont like being charged over 13.5 volts...most Jeep charging systems charge about 14.5 to 14.9 so you basically cook the battery and shorten their life span. This was told to me be a rep. from Optima battery before they were purchased by Interstate.

gcg
11-14-2007, 12:34 PM
Optima's dont like being charged over 13.5 volts...most Jeep charging systems charge about 14.5 to 14.9 so you basically cook the battery and shorten their life span. This was told to me be a rep. from Optima battery before they were purchased by Interstate.
Looks to me like they just don't like living very long! As mentioned in an earlier post, I've run a Yellow Top dual battery system in my XJ, charging through a diode isolator setup, for about 6 or 7 years. The diodes are in line with the charging source so they will lower the charge voltage to the batteries (at least when there's any substantial charging current). Yet, I seem to replace a battery every year at $200 a pop. I'm pretty much through with Optima batteries at this point.

dsy
11-19-2007, 10:55 AM
I heard that about the Optima's after I already installed a yellow top under the hood. I'm trying one of the new Sears deep cycle sealed batteries mounted under the Engle fridge in the back seat now as my second. So far its holding up good. I was told when I bought it that they were not as prone to the over charging problem like the Optima.

http://img476.imageshack.us/img476/1585/diehardvt9.jpg

seer
01-22-2008, 01:16 PM
Has anyone checked out the Deka Intimidator? A guy at the local shop keeps recommending them to me over the yellowtops.

MichaelW
01-23-2008, 10:19 AM
I am running the Napa gel cell at the moment and so far so good but not really had a chance to test it out a lot. According to the scan gauge the JK is regularly running at 14.3-14.6 volts output from the alternator.

duskydriver
02-14-2008, 08:42 AM
Has anyone checked out the Deka Intimidator? A guy at the local shop keeps recommending them to me over the yellowtops.

I used to be a diehard Interstate guy. Then I bought Deka's for the boat. 27 series deep cycles, they are 4 years old and still kicking!! Driving a truck all over the country I sometimes don't get to the boat for a few months, and she kicks over every time.

AndyR
04-19-2008, 01:54 PM
Did you hear anymore Andy? I am curious as I am looking for a place for batteries. I would like to have two "spares" for my welder that could be somewhat handy and am thinking of under the rear seat with some gel cells.

Oops I spaced on this. I just sent Yawan an email on the subject.

Andy

PS will be in Panamint April 25-27.

ColinW
09-05-2008, 01:27 PM
Optima's dont like being charged over 13.5 volts...most Jeep charging systems charge about 14.5 to 14.9 so you basically cook the battery and shorten their life span. This was told to me be a rep. from Optima battery before they were purchased by Interstate.

Sorry to drudge up an old thread, but I needed to correct some mis-information here...

Just got off the phone with an Optima tech who explained the rumor I told him I had heard about the JK's alternators being too large...he said it should be fine as long as the alternator charges between 13.7 to 14.7 V. He didn't really seem to even care about the amperage. Now, the reason I think this is tomfoolery (on Quadratec's part) is because according to the spec that the Quadratec rep posted (if it's true) - of Jeep charging systems charge about 14.5-14.9, this would be at the upper limit of what the Optima could take. Plus, the Quadratec rep had quoted Optima being bought by Interstate, which is untrue because they are owned by Johnson Controls and have been for quite some time now.

Edit: And, I just talked with the same gentleman over at Optima again, and he stated that a 14.9V alternator will be fine, just as long as it doesn't go over 15V...He stated that most likely any battery would eventually get damaged if your alternator charges over 15V. I showed him this post, and he immediately disputed what Quadratec said.

Anyone have a good method to check the output of our alternators besides just putting a voltmeter across the battery terminals when the engine's running?

tgrt
09-05-2008, 04:23 PM
My spies tell me that Yawan Smith (Kodiak Industries & Premiere Power) has just put a dual setup in the Cal4wheel giveaway vehicle. Me'tinks I'll be giving him a call.

I gave up on him. I was messaging him late last year and he made it sound like it was all but ready and priced. Then I couldn't get him to contact me again. It put a nasty taste in my mouth, so that's it for me.

Benchmark Designs Inc.
10-28-2008, 09:10 AM
Just in case word has reached over to the Electrical Tech Section, dual battery kits are being manufactured.

Original Thread http://www.jkowners.com/forum/showthread.php?t=4024

Our Site www.benchmark-designs.com

jacktuttle
11-18-2008, 03:02 PM
I'm running a dual battery system in my XJ. I use two Optima yellow tops and have a diode isolater system. With it, the alternator charges both batteries in parallel but they cannot discharge through eachother. So, one can be run completely dead and the other will still be fully charged. The batteries operate separately, not in parallel.

It all sounds great but I've found that the yellow tops don't last very long in this situation. I replace one each year at about $200 each. Way expensive! I don't know for sure but I suspect this is because the charge sensing lead is attached to the junction of the two diodes, which is a diode drop away from the battery voltage. So, it is going to regulate that voltage during charging and the battery voltage will be lower (by a diode drop). The net of all that is that the batteries are being charged for most of their cycle at a voltage somewhat less than the "preferred voltage" and may end up suffering a bit as a result. As I mentioned, I'm not completely certain on this but it seems to make sense to me.

As an alternative, you might want to check out the Hellroaring Technologies products (www.hellroaring.com (http://www.hellroaring.com)). Funny name but their product seems to be a better approach. They use a different technology that has a smaller voltage drop across it. They have several different products that allow you to configure your batteries in many different ways.

If I decide to do a dual battery setup in my JK, I will be looking at them, too.

The Charge Sensing lead should be connected to the main battery. Lets say that your jeep uses 40 amps when running. Lets also say it wants to charge back 30 amps from starting the motor for 70 amps total. That is what the sensing lead will ask of the alt. Now lets say the second battery needs 50 amps to recover from a winch operation. It will draw off about 1/2 of the charge. The sensing lead will see that it is not getting the full 70 amps requested and increase the request until it is getting the full amount or reaches its max charging cap. Even if it does get to full cap that will not last long because as the batteries charge back up the request for amps is lowered. I would recommend putting a 50 Amp self resetting breaker to the second battery so it can not over load the alt but that is up to you. Also be sure the isolator is has high or higher than the max output of your alt.