Dual Batteries & Switch

[hemrides]

Does anyone have dual batteries and switch setup? If so can you provide some details?

1. What brand of switch? What ones are better & why?
2. Did you have to install a different alt. to handle the extra load.
3. Battery Type

I have a 2004 TJ stock Jeep. It has a second battery tray already installed on the drivers side.

Thanks,
Dave

[oz97tj]

1. As for the switch, I've heard of everything from no switch to fancy computer controlled deals. Again, depending on the use, some sort of basic isolator would work for most people. It would just keep the secondary battery seperate from the starting battery so if it was drained to far, your orginal batter would still start the vehicle, instead of them both being dead. However, if you don't really even intend on having much of a load on the batteries when the vehicle is off, running the two in parallel with no isolator would be fine. It's the equivalent to the larger gas tank thing again. The problem would be you still could end up with a dead electrical system if there is a draw when the vehicle is off. However, for winching, you'll leave the vehicle running almost always anyway so that shouldn't be an issue.


2. You wouldn't need a different alternator. There will be no greater load. Having a second battery just adds a larger capacity. Kind of like adding a bigger gas tank. A larger alternator would only charge the batteries faster / or prevent them from discharging as fast.

3. Battery type would depend on your use. Many people use deep cycle batteries as a second battery if using for heavy winching use, as they are more suited to being deeply discharged.

Lastly, I know that tray is there, but I'm not sure if you'll actually have room to mount a battery in it, because of the master cylinder. I think most kits usually mount dual batteries side by side in the area of your stock setup.

[shawn]

I've never needed dual batteries. The only time I think I might possibly need them is up in Canada or someplace else out of this state. In Michigan, I've never been in an extended winching scenario.

[oz97tj]

I've never needed dual batteries. The only time I think I might possibly need them is up in Canada or someplace else out of this state. In Michigan, I've never been in an extended winching scenario.

There has been a few times (I'm a slow learner) where I went out exploring in the snow by myself late winter. With deep snow, with a crusty surface, I've had to do some extended winch pulls. They weren't the hardest pulls, but long, and repetitive because I'd run out of rope and have to start over. In one length of rope, my battery was basically dead and I was running on alternator. I ended up doing a lot of sitting idling at 2k rpm to charge the battery back up. Yeah, it was dumb and I shouldn't have been there in the first place. A dual battery would have been nice, but then again, I still would have discharged them both in the process so it woudn't have gained me that much. I could have at least got through one full line pull though instead of having to stop half way through a pull to charge the battery.

For me, I like the idea of a dual battery for camping in remote areas and exploring. Running a fridge, and possibly other electronics at night off the battery, but still having the orginal battery to start the rig. Winch pulls are just a bonus if doing a long pull.


Edit: I should also include that I don't currently have them. I agree with Shawn they aren't NEEDED, but they are nice in some situations. I just think there are other mods that are more useful day to day that get my money first.

[hemrides]

Thanks Oz & Shawn for the feedback. Will give this more thought.

Dave

[shawn]

I mean, I plan someday to have 2 batteries, but it is low on my list. One good deep cycle (like an Exide) will go pretty far. If I'm winching sooooo much that my one deep cycle can't keep up, I probably shouldn't be there, just yet :)

[300Grand]

Dave,
As far as what type of battery (or batteries) to get, with out a doubt get an AGM battery. Optima is one brand of AGM battery, however, they are way over priced for what you get. I can get you a better price on a much better AGM battery from DEKA Battery. Why I recomend an AGM is that they absorb energy faster then a regular flooded battery, therfore they recharge quicker after a winch pull. Plus they are much more durable then a flooded battery.

[DieselMTU]

Painless wiring has a nice set up. Comes with a 3 way switch. Run either battery alone or run both. There is another way the system works to allow you to charge one or both batteries at a time. I have not installed yet, just read up on it a bit

You may need to consider running a larger alternator depending on the amps you are pulling. Two batteries, with a diode can help with that, but the more current you draw, the harder the alternator has to work to charge. This of course depends on your set up. Add enough lights, a winch, and a few other goodies and you will prolly shorten the life of the alternator.

[OldSailor]

Keep in mind that if you use two batteries, they should be of the same type. For example, DO NOT use a starting battery (e.g., Optima Red Top) as one of them and a deep cycle battery (e.g., Optima Yellow Top) for the other. Such a setup will unbalance the system and result in charging inefficiency.

Speaking of Optima batteries, I used them for several years in dual-battery configuration both in my Cummins Dodge and in my CJ7, both equipped with winches and off-road lights. I was not pleased with the Optima batteries for two reasons: (1) They became really over-priced; and (2) They had a fairly high failure rate -- Of the four batteries, I usually had to replace one of them every 8 to 12 months. I sold the Dodge, but I switched the Jeep over to Exide deep-cycle gel-cell batteries (used by NASCAR) that cost about $50 apiece less than the Optimas, and that was about 2-1/2 years ago with no replacements since then.

The Dodge came with an very expensive (over $300) OEM 130-amp alternator. I had the Jeep's inexpensive 65-amp OEM-type Delco alternator rebuilt with different windings by a local starter/alternator shop (South side of Ford road between Newburgh and Haggarty), resulting in a 110-amp alternator. Cost me less sthan $50 for the conversion, so it was a lot cheaper that some of the high-priced alternators on the market.

I'd recommend going with the continuous duty cross-over solenoid to isolate and connect the two batteries, rather than the solid-state setups, because the latter drops the charging voltage about 0.7 volts, resulting in a slower recharge. Also, once you get the heavy-duty cross-over solenoid, do not spend the exorbitant amount of money they want for the cross-over switching system. For less that $4 in parts (switch, wire,terminals), I rigged up mine with a 3-position switch. In Switch Position 1, the solenoid is activated by power from the Main battery as soon as the ignition key is turned to START or ON. In this position, both Main and Auxiliary batteries are tied in parallel, and the alternator will charge both of them. In Switch Position 2, the solenoid is not activated, and the two bateries are isolated from each other. In this position, using a winch or a high-current stereo amplifier tied to the Auxiliary battery will not drain the Main battery, leaving the Main battery charged up to start the vehicle if needed. In Switch Position 3, the solenoid is activated from power from the Auxiliary battery. This positioin is useful when you have screwed up and left your lights on all night, discharging the Main battery. Since the Main battery is dead, you can't tie the two batteries together in Switch Position 1. But Switch Position 3 will tie the two batteries together using power from the Auxiliary battery. If 2 ga. cables are used to connect the two batteries to the cross-over solenoid, Switch Position 3 will allow the engine to be started with power from the Auxiliary battery.

Normally, when winching, I'd leave the cross-over switch in Switch Position 1, and leave the engine running during the winching operation. However, if the vehicle doing the winching is "in extremis" and tilted too far, the engine might not run. In this case, I'd use Switch Positioin 2, so that I could at least re-start the engine when I was done if I ran the Auxiliary battery down too far while winching.

In order to wire up this configuration, you only have to purchase a toggle switch commonly called a "three-position center-off" switch. It is also called a ON-OFF-ON 3-position switch. Make sure you get a switch in which all three positions are stationary positions, and that none of them are momentary (spring-loaded) positions.

[knaffie]

I made my own dual battery setup using a marine switch that includes off, B1, B2, and both settings. Cheap and simple with no solenoids or switches to fail. I didn't have the cash for AGM batteries, so I used the Everstart Extreme batteries from Walmart, and they are holding up great so far (3 years). I wouldn't run an Optima if somebody GAVE me one. I've PAID for enough of those pieces of junk, and won't deal with the hassle ever again. The best battery for the dollar out right now is the Diehard Platinum, which is a rebadged Odyssey AGM battery. Its superior to even Optima's Yellow Top.

Let me know if you want any more details, I'll be glad to help.

http://i128.photobucket.com/albums/p200/knaffie/dual%20battery%20setup/DSCN4045.jpg

http://i128.photobucket.com/albums/p200/knaffie/dual%20battery%20setup/DSCN4137.jpg

http://i128.photobucket.com/albums/p200/knaffie/dual%20battery%20setup/DSCN4053.jpg

http://i128.photobucket.com/albums/p200/knaffie/dual%20battery%20setup/DSCN4139.jpg

[hemrides]

Thanks Knaffie...I was wondering if a marine switch would work. I had concerns that the salt and road grim would damage it. I had this setup on both of my boats and it worked like a champ. I appreciate the pictures.

Merry Christmas to all...thanks again for your input.

Dave

[knaffie]

Corrosion is definitely a valid concern. The switch I used had bare brass terminals. I don't drive my truck on the road and definitely not in the salt, so its not a concern for me. If you used that switch, I would try to put it in an enclosure, like the gray box you see under the hood of my truck. I got it from automationdirect.com

[rentalrider]

Knaffie that's a great looking setup. I currently run a cj with duals. I also wouldn't run optimas again if you paid me. Another thing to consider is if you don't run a split of some sort, use the EXACT same batteries. I picked them with same exp date/lot #'s, etc. I don't currently run an isolator but still have a solenoid mounted on top if I ever decide to go back to that style. I run them together in series, or wait, parallel. whatever :) Haven't had issues lately, not since optimas kept crapping on me. I run a 140amp alt with plenty of off road lights and a 10k winch and an ected locker with seems to pull significantly, too. Good luck I think it's worth it.

[knaffie]

100% true about the batteries being the same. I bought two identical ones as new, made sure they were made on the same date.

Yours are in parallel. Series would be 24 volts!

[WhiteRhino]

I've run dual batteries for years with no special switching mechanism. Just wired together in parallel. For the past 8 years, I've run dual Optima yellow tops. I know there is lots of bad press on them but one is the original and the other failed this past spring. 7 years with a lot of winching seems pretty good in my book. I understand all the reasons for isoloation but on a personal note, I just don't see the justification. I've never had a component that draws down my starting battery where I would need the other one for a jump start. And, in my mind, that is the one and only reason for isolation. For winching, you want them both providing power. Also, on most runs, someone has jumper cables. If you have a stick shift, you also have the option to do a pull start if you run your batteries down.

RE the "exact" same batteries, I don't buy it. I did a run down test on both of my batteries and found that one would not hold charge over 10v and the other held at 12.4 or something like that. I allowed it to sit, and over the course of a couple weeks, it didn't drop a bit. I have read in multiple places where the batteries need to be the same age but have never been able to research "why". To me, it's a mechanical/chemical component. It either stores energy at the proper level or it doesn't. I would expect the old one to fail in the next year or 2 but I can't see where it would impact the new one. Other than........ as the old one starts to fail, the new one sees a greater draw, which unless heavily taxed like winching, it's made to do. So, where is the issue? And if it were all that important, how come when I originally added my second battery, after about a year of running a single, why have they both lasted 7 years?:idea:

For me, simplicity is the name of the game.

[knaffie]

I agree about simplicity. That's why I used a simple and inexpensive marine switch. Companies like Painless make a kit that costs hundreds and includes solenoids, switches, fuses, etc. - NO THANKS!