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Discussion Starter · #1 · (Edited)
Here’s my completed Dual Battery Project.

My goal was to install a second battery to use as a backup for the primary battery. I started by reading all of the articles I could find. I decided to keep the OEM battery at first and add an Odyssey 925 since it would fit nicely in limited space available under the hood of the 06 Taco. I plan to upgrade the OEM battery to an Odyssey PC1700 when I install the winch.


[edit: 01/11/08, since I did this post last year, I upgraded the primary battery to an Odessey PC 1700 and rerouted the aux fuse block to it, so the PC 925 funtions as backup battery only. I should write these changes up some time, but I thought I should mention it here and did not want to bump an old thread. There is an updated pic at the end of this write up. Also, I originally planned to put an aux relay block next to the PC925. In hind sight, I could have mounted the aux fuse block in a larger project box directly above the PC 1700 and then had room for relays too. The location above the PC 1700 might also be good for a winch solenoid.]



This is what it looks like with cover on. [edit: This photo shows the aux fuse block powered by the PC925. It is now powered by the PC1700 - see last photo in this write up]




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Here are the high level steps for the installation process:
This shows the location for the components:




Parts List and information

http://ttora.com/forum/showthread.php?t=63430




Step 1: Relocate OEM R/B No.2.
This required fabricating a small piece of aluminum as shown in the second photo. Detach the relay block from the primary fuse box, by sliding it upward firmly.



This shows the Relay Block in its new position


Step 2: Make bottom and top plates for battery.
These are ¼” aluminum plates with counter sunk holes for the bolts running down through the wheel well.
Bottom plate (holes 1-4 correspond to holes drilled in wheel well in next step). Holes A and B are for lag bolts that connect to top plate.



Top plate (large holes are for lag bolts to secure battery, small holes are counter sunk from the other side for bolts running up into the project box that sits above this plate.



Step 3: Drill holes in wheel well for battery mount.
Use bottom plate for battery as template for holes in wheel well. Position the aluminum plate in the desired location and mark where holes the will be drilled, for positions 2, 3, and 4 this is directly above the flat parts of the wheel well. A bracket is needed for the upper left position (holes 1 and 5).

For the aluminum plate to sit level, I had to fashion spacers for every position except #3. I just used a really thick washer for position 2, a large nut for position 3 (sorry, not shown), and fashioned a bracket position 1. A large washer on the under side is needed for position 2 because the existing hole is too big. The bracket on the left needs a slight angle because the flat part of the wheel well is not parallel to the aluminum plate. To make the bracket I first bolted the tray at positions 2, 3, and 4, and then bent a 10guage solid core wire to the desired shape. I then bent a piece of galvanized steel to match the wire template. (I’m not experience with metal fabrication - I was surprised the worked on my first try). Once the bracket was bolted at position 5 it was easy to tweak it to fit flush to the aluminum plate. Mark and drill hole 1 in the bracket as the last step.


Step 4: Mount bottom plate with bolts for securing battery.
The holes for the long lag bolts that that run up to the top plate were filed square to keep them from turning when the top nut is tightened.



Here is what battery looks like installed


Step 5: Mount project box to top battery plate and fuse block inside project box.
Note: I used ¼” coupling nuts to create a space between the bottom of the fuse block and the bottom of the project box. The space is where the wire runs from outside the box. The coupling nuts had to be ground down about 1/8” so that the fuse block fit inside the project box. A slightly taller project box could be used instead.




Step 6: Mark and cut holes for grommets in project box.
One hole for #4 wire to battery two holes for wires from fuse block to accessories.



Step 7: Mount Battery, fuse block, 150A Main Fuse, and Battery Isolator
Hellroaring 150A Fuse Holder


Hellroaring Battery Isolator



Step 8: Make Cables, install cables.
Use a piece of rope to measure cable lengths. My local West Marine store had all the tools I needed except for the heat gun.
I still need to get some ¾” split conduit to protect the wires.

Finished product


Thanks to all of those who posted their dual battery set ups and other useful information. Below is a partial list of resources that helped tremendously with this project.

References:
About batteries http://www.fridge-and-solar.net/dual_bat.htm
http://forum.sounddomain.com/forum/ultimatebb.cgi?ubb=get_topic;f=5;t=009326;p=
http://www.teddnet.com/index.htm
About isolators http://www.off-road.com/chevy/reviews/hellroaring/
http://www.cardomain.com/shoptype/Battery+Isolators/Regulators

http://www.ttora.com/forum/showthread.php?t=11679&page=2 (This is bajatoco's post with long explaination by dick foster on page two about isolators)
http://www.ttora.com/forum/showthread.php?t=32527(Dual Batt post by Drabnor)
http://www.yotatech.com/showthread.php?p=1022559
http://ttora.com/forum/showthread.php?t=12105&highlight=odyssey+1200 (Dick Foster used odyssey 925)
http://24.174.48.38/dual_battery.html
http://www.ttora.com/forum/showthread.php?t=49249&highlight=dual+battery+installation
http://www.bajataco.com/dualbatts/dualbatteries01.html
http://www.manoian.net/jeep/dual_batteries.html
http://www.toyota120.com/html/4runner_dual_batteries.html
http://www.mp3car.com/vbulletin/showthread.php?t=6298&highlight=deep+cycle+battery
http://www.mp3car.com/vbulletin/showthread.php?t=74124
http://www.commtechreview.net/jeep/nwpdualbatt.htm
http://www.ttora.com/forum/showthread.php?p=587817&mode=threaded
http://www.tundrasolutions.com/forums/tacoma/74920-2005-tacoma-cobra-75-wxst-cb/
http://www.uuhome.de/william.darden/ (Deep cycle battery faq)

http://www.rvsolarelectric.com/

http://www.oramagazine.com/pastIssues/0503-issue/050301t-maya-hunter.html
http://www.arb.com.au/arb_dual_battery_systems.htm


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[edit: 01/11/08, Here's the updated pic with the Odessey PC 1700 replacing the the OEM battery. The Aux fuse block now gets power from the primary battery.]
 

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Great write up and Pic's. Keep us posted on how it works?
 

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wow this going in my favorites in case i wanna do this down the line
 

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awesome write up! pics and diagrams are perfect. thanks!:cool:
 

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Did you do anything with the alternator? Add an extra charging wire or grounding wires?

I had a dual battery setup on a previous vehicle. I used an Orion battery isolator. The only bad thing about dual batteries is the added load that it puts on the alternator. I had to get a new alternator every couple years.
 

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Discussion Starter · #9 ·
Did you do anything with the alternator? Add an extra charging wire or grounding wires?

I had a dual battery setup on a previous vehicle. I used an Orion battery isolator. The only bad thing about dual batteries is the added load that it puts on the alternator. I had to get a new alternator every couple years.
The truck has a 130A alternator that was part of the tow package (http://www.toyota.com/tacoma/options.html ). I'm hoping that will do.

I hadn't planned to replace the alternator wires - I've read about the "big three" but thought that was more of an overkill audiophile thing.

Does anyone know how to tell if the charging and alternator ground wires are up to snuff? I'm more concerned when I replace the OEM battery and add a winch.
 

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Discussion Starter · #11 ·
Excellent writeup, thankyou for posting this. :clap: Where did you get the project box you used to mount the fuse block in?

I used one from Radio Shack (6x4x2). There are better boxes out there but none were narrow enough to fit over the the top battery plate that I had already made.

Here are links to other sources for project boxes:

http://www.designnotes.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=G313&Category_Code=seae-b
http://www.hammondmfg.com/scpgPL.htm
http://www.polycase.com/category/size/extra-large/dc-series.html
http://www.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=664

BTW all of the components are listed in the newbie thread I posted when I was looking for help with the plan. http://www.ttora.com/forum/showthread.php?t=63430
(I should make that more obvious in this post.)
 

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The truck has a 130A alternator that was part of the tow package (http://www.toyota.com/tacoma/options.html ). I'm hoping that will do.

I hadn't planned to replace the alternator wires - I've read about the "big three" but thought that was more of an overkill audiophile thing.

Does anyone know how to tell if the charging and alternator ground wires are up to snuff? I'm more concerned when I replace the OEM battery and add a winch.
Remember that the stock wiring is designed to handle the trucks stock electrical system, plus trailer lighting, and maybe some small accessories. If you add a substantial electrical load, then the stock wiring needs some upgrading. If you want to do it all properly.

I think it's a worth while investment to add 4 guage wire on top of the stock charging wire. Just take off the nut on the alternator terminal and add a cable with ring terminal on the end.

Adding a bigger ground wire is good too. Remember that what goes in must go out. The size of your ground wires should match the size of your positive wires.
 

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Nice set-up. I have a dual system and isolator also. Your wireing seems to be very different from mine. Did you relocate the alternator cable from the fuse block and send it to the isolator? From the pic it looks like you aux battery will still drain your stock one, but the stock one can't drain the aux. Also, what is the jumper on the isolator for? If you were to disconnect the positive wire from the aux battery and tested it with a volt meter, without the engine running, is there still 12v in the wire? If there is, anything connected to the aux battery will also drain the stock one.
Sorry if i'm wrong. Just guessing from what i see. Still very good work.
 

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Discussion Starter · #14 · (Edited)
If you were to disconnect the positive wire from the aux battery and tested it with a volt meter, without the engine running, is there still 12v in the wire? If there is, anything connected to the aux battery will also drain the stock one.
Sorry if i'm wrong. Just guessing from what i see. Still very good work.
You are absolutely right about the backup battery draining the starter battery. I got the wrong model isolator for this setup. It should have been a BIC-95150. Thanks for catching that!

[edit: a bit more reading turned up that I just need to move the wires so that the primary battery is on post A and the backup battery on post C with the middle post unused. No crossover cable is needed.]
 

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Very nice setup. I am still tempted to run dual batteries, but with the tow package I have the 130 amp alt, and HD battery (to be replaced with a better one) and dont run that much crap, I do like the ability to jump myself, espically since my new truck is an auto...

One question, whats with the facination with isolaters? IMO its a better setup to run a HD Continous Duty solenoid to a oil pressure switch (motor on batteries in parallel, motor off two batteries)... makes charging and wiring easier. In a couple of my dads rigs we used to run isolaters and they all failed, all of his dual battery rigs now run oil psi switch to a solenoid, and its much easier.


Man, just looked at my truck.. cant fit a battery there the A-TRAC brake setup is much larger... oh well...
 

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I used one from Radio Shack (6x4x2). There are better boxes out there but none were narrow enough to fit over the the top battery plate that I had already made.

Here are links to other sources for project boxes:

http://www.designnotes.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=G313&Category_Code=seae-b
http://www.hammondmfg.com/scpgPL.htm
http://www.polycase.com/category/size/extra-large/dc-series.html
http://www.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=664

BTW all of the components are listed in the newbie thread I posted when I was looking for help with the plan. http://www.ttora.com/forum/showthread.php?t=63430
(I should make that more obvious in this post.)
Thanks again arott!
 

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Here’s my completed Dual Battery Project.

My goal was to install a second battery to use as a backup for the primary battery and as a power source for the after market accessories.



I plan to upgrade the OEM battery to an Odyssey PC1700 when I install the winch.
Only thing I see wrong with this... is that you got the battery principles back asswards as far as which should be the starter and which will run the aux loads.

the PC1700 should be yer aux. battery for powering high load accessories like a winch or what not.

But you really don't want the winch or other high loads running off the starter or the battery wired in conjunction with the OEM ignition sys.

I also think that dual batteries should be as close to the same output and capacity so they will charge at the same rates.

but hell... what do I know.

it's JMO
 

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Discussion Starter · #19 · (Edited)
Only thing I see wrong with this... is that you got the battery principles back asswards as far as which should be the starter and which will run the aux loads.

the PC1700 should be yer aux. battery for powering high load accessories like a winch or what not.

But you really don't want the winch or other high loads running off the starter or the battery wired in conjunction with the OEM ignition sys.

I also think that dual batteries should be as close to the same output and capacity so they will charge at the same rates.

but hell... what do I know.

it's JMO
When I first set this up, I used the PC 925 as a "house battery" and as a backup to the OEM starter battery.

Later, I got the PC1700 and now power everything off it it. The PC925 is just a backup battery. This is a very standard setup.

So I'm not sure what is backwards...

Here's the current wiring diagram:



[Edit 05/03/10 this weekend I actually needed this damned thing. Peace of mind is one thing, actually flipping a switch and getting back on the road is another. I've tested this setup by diconnecting the PC1700 before, this is the first time I've run it down by mistake. It worked...]
 

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When I first set this up, I used the PC 925 as a "house battery" and as a backup to the OEM starter battery.

Later, I got the PC1700 and now power everything off it it. The PC925 is just a backup battery. This is a very standard setup.

So I'm not sure what is backwards...
I think what Dell means is you should be using the larger battery to power your big loads, and the smaller battery as the starter/'house' battery. For example, when you're winching, the winch draws power from the big, deep cycle battery, and the alternator charges the big battery without having to go through the isolator. The small battery basically will only be for the starter, since the isolator will join the batteries when the truck is running. That means that A) your accessories won't ever draw down your starting battery and B) because of that, not only would it be hard to kill the starter battery, it won't have the risk of damage from deep discharges.

The way you did it isn't 'wrong', just a bit weird. You're putting ALL the loads on one battery, and using the other one as nothing but a backup and extra power when the truck is running.
 
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