Single Tray Dual Battery Set-Up

I have had some folks express some interest in this dual battery alternative so I though I would do a brief write up. It was actually fairly simple and did not require any special order componets though I remember having to call around to find the red top 6vt Optimas.

The first thing to do is to be sure on the dimensions with which you are working. My 12vt die-hard was 8" deep, 7" wide, and 9" long. It worked out that this allowed perfectly for the Optimas which were 3.5" inches wide and 9.5"long. The Optimas were only 7" deep which provided for their edges to fit under the grid support/fender lips.

I did do a small amount of custom fitting to the battery tray in one small spot with a razor knife(sorry I don't have pictures of this spot but it is fairly obvious as you are fitting). I also had to "adjust" one of the rubber insulated bolt heads that hold the radiator bracket (3 or 4 whacks with a hammer). After those two minor adjustments the batteries feel like they snap in with the edge of the Optimas fitting just ever so slightly under the metal grid support.

Dropping the 12vt in last prevents any movement of the Optimas or lateral movement of the 12vt. Connecting cables and snug fit will secure the 12vt from any vertical movement. You could rig up hold downs, but I chose not to since the set-up feels very tight and secure. Even if I did a Christo Slee rollover I believe that my batteries would not budge (I would have much bigger worries at that point anyhow).

Wiring is pretty simple. Common ground between the 12vt and the Optimas as is apparent, but not obvious from the photo. Starting and stock charging functions are ran off of the postive of the Optimas. Also, a positive cable is ran from this terminal to the sure power battery seperator (model 1314) I bought from NAPA. Then another postive cable is ran from the other terminal on the battery seperator to the positive terminal on the auxillary 12vt battery.

The seperator contiually charges the Optimas (main battery), but as soon as they hit a certain voltage it closes (allows the batteries to connect) to also charge the auxillary battery until the two reach a certain voltage. If the main battery falls below a certain voltage level the seperator opens and the auxillary is no longer connected. The seperator continually goes between these these states until the ignition (charging) is turned off. When no current is present the system opens and the two batteries are disconnected.

There is a ground wire that must also be attached to the seperator, but the unit comes with thorough directions to explain how to hook it up. There are two terminals I have not used yet that I may employ at the time of my next upgrade. These other two terminals allow you to use a switch to manually connect the two batteries from the cab. You would do this if your starter battery failed or if you wanted extra power for starting in the cold or winching. Currently I have some compact jumper cables that suit this purpose .

So that is pretty much the long and the short of it. I will mention that at one point I lost solid connection between the two 6vts and had to tighten the link up even though it looked solid. Terminal covers are a very good idea with everything being so close. I eventually plan to move the seperator to beneath the battery tray and hook up the parallel switch when I upgrade the die-hard 12vt to an Odyssey dry cell(these operate as deep cycle or high cranking amps-there are other potential dual battery combinations through Odyssey that I have not yet explored). And finally, I puchased terminals and wiring from a marine shop though I am sure you could go elsewhere.

Rusty Shackleford said:

Man, that's just what I need. Thanks for the write up.

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No problem. Let me know if you have any questions...

Looks good.

It's nice to see a different solution for the problem.

Bigshone said:

Looks good.

It's nice to see a different solution for the problem.

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Thanks.

the post i beem searching for thanks

so i guess that means those of us that have dual batts the real way can have quad bats? intresting non the less

lx450landcruiser said:

so i guess that means those of us that have dual batts the real way can have quad bats? intresting non the less

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Quad batteries I guess if that is an efficient use of space for you. I think 2 good ones are enough for me.

My air compressor still sits next to the radiator overflow where the passenger side battery would have to go. I know that if I need more space under the hood I can get it by easily moving the air compressor.

Not to mention an easier install with less cable, less weight, and less distance between posts.

Interesting approach. I believe Robbie used 2 similar 6V batteries in series but he installed his behind the RR cargo area panel. I haven't seen pictures though.

Suggestion. You should consider changing the position of the 6V battery on the far right side of the above picture. That Pos terminal is extremely close to the body which is grounded. A collision on your LF fender or 10 miles of washboard or just time in place can create a dangerous situation. IMHO, you could rectify this by turning that battery 180* with the negative post closest to the body.

jamisobe said:

Even if I did a Christo Slee rollover I believe that my batteries would not budge (I would have much bigger worries at that point anyhow).

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You make light of the problems created by a rolled vehicle on the trail but it isn't funny and you WOULD have a bigger problem if those batteries plop out of the battery tray and onto your bonnet 'cause now you have a burning vehicle that is sitting on it's roof and your winch won't work because you've shorted out your batteries. I'd say that's a much bigger problem than a flop.

One of my bosses would always tell me "Plan for the worst and hope for the best."

-B-

Beowulf said:

Interesting approach. I believe Robbie used 2 similar 6V batteries in series but he installed his behind the RR cargo area panel. I haven't seen pictures though.

Suggestion. You should consider changing the position of the 6V battery on the far right side of the above picture. That Pos terminal is extremely close to the body which is grounded. A collision on your LF fender or 10 miles of washboard or just time in place can create a dangerous situation. IMHO, you could rectify this by turning that battery 180* with the negative post closest to the body.

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Thanks for the suggestion. However, The terminal can't touch the fender. It is solid and won't move in that direction regardless of vibration. The thick terminal cover protects from objects crossing with other terminals which is more protection than most have on their standard battery set-up.

I have had the set up for 3 years, driven tens of thousands of highway miles and have been on many hairy off-road rides with no problems. It's tested and reliable.

Beowulf said:

You make light of the problems created by a rolled vehicle on the trail but it isn't funny and you WOULD have a bigger problem if those batteries plop out of the battery tray and onto your bonnet 'cause now you have a burning vehicle that is sitting on it's roof and your winch won't work because you've shorted out your batteries. I'd say that's a much bigger problem than a flop.

One of my bosses would always tell me "Plan for the worst and hope for the best."

-B-

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The 12vt is unable to move in any direction laterally and with cables attached it is 100% immobilized whether you shake it or turn it upside down. With cables attached it is impossible for the 6vts to experience any movement with the 12vt in place. Fortunately, for whatever it would be worth, a rollover would not result in batteries flopping out. I'd bet you a large sum of money that you couldn't even pull the 12vt out if you used both hands while standing on the fender and grid support (try that with many of the hold downs that some vehicles use).

IF there is any increased risk of grounding out in a severe accident I would suspect that it would be neglible or even less than other set-ups depending on the dynamics of the accident. I don't see the risk you raise as being a reason for real concern.

It has worked great, weighs less, its easier to install, and it saves significant space. Cost is probably comparable to a conventional dual set-up since a 6vt Optima cost nearly the same as a 12vt Optima and you need 2. Of course I didn't need to buy as much cable or a second battery tray.

If you really wanted to "plan for the worst and hope for the best" you wouldn't even walk out of your house let alone take you truck off the street for fun.

You know, I think you guys may be right. If you've flopped or had a wreck then the last thing you'll be worried about while you're trying to get out of the vehicle is that smoke coming from under the bonnet.

-B-

Sample Size of 1, Rusty.
-B-

Beowulf said:

You know, I think you guys may be right. If you've flopped or had a wreck then the last thing you'll be worried about while you're trying to get out of the vehicle is that smoke coming from under the bonnet.

-B-

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Fires started from crushed batteries are a risk in any accident. You could build a special reinforced and insulated cage around your batteries or eliminate batteries by using a removeable cranker, otherwise there isn't much you can do beyond avoiding accidents that will guarantee any vehicle of having no risk of shorting its battery (ies).

Use a heavy duty bumper.

Even if you do you could still see your bonet or your front grid crumple in a manner that crushes your battery or causes contact between your posts.

If you have a battery on each side of your car it makes sense that the risk of this happening are also increased.

So it stands to logic that having a dual battery system in any form will increase your risk of battery complications at various degrees in differing accident situtations.

Rusty Shackleford said:

Flop and burn of this sample is zero.

If it was seriously a major concern, a $2 piece of rubbermaid would cover the whole tray and issolate the terminals from any contact whatsoever. Plus, you can use the rubbermaid for a serving dish while on the trail.

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Exactly, why not take the time to at least cover the terminals. It will only take one flop or rollover to see whether or not the battery will shift and terminals will touch the hood/body. If you are trapped in a rolled over vehicle, the last thing you want is several batteries shorting and causing the vehicle you are in to burn. That test sample will probably only happen once. No doubt the current setup is more than adequate to hold the batteries secure in day to day/offroad situations, but I would want to feel a little more secure in case of accident.

firetruck41 said:

Exactly, why not take the time to at least cover the terminals. It will only take one flop or rollover to see whether or not the battery will shift and terminals will touch the hood/body. If you are trapped in a rolled over vehicle, the last thing you want is several batteries shorting and causing the vehicle you are in to burn. That test sample will probably only happen once. No doubt the current setup is more than adequate to hold the batteries secure in day to day/offroad situations, but I would want to feel a little more secure in case of accident.

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Hence, the rubber terminal covers. The 12vt postive cannot touch the bonnet or the body with the cables connected even when standing on the truck using both hands pulling with full force. It is as secure as secure.

Why would you bother if you already have a dual set-up? Space maybe? Weight savings may not be overly significant, but a little here and a little there adds up. Otherwise, I would stick with the "real" dual battery configuration that many already have in place.