electrical help requested - adding aux power

[buldyourown]

I have an '07 Tacoma DC TRD Sport.
My long term plan is add a second battery with an isolator from Wrangler NW.
I have several accessories that I'd like to wire up before the xmas holiday road trip. I don't really have the time or the money to do the double battery properly before then.
I also plan on adding a blue sea fuse block as my distribution panel for all these new toys. What would be the proper way to wire in the fuse block now, and still leave it ready for the double battery later. I don't want to do anything twice. My initial plan was to simply run a 8ga wire from the battery all the way to the fuse block and mount it behind the rear seat. Then I realized that all my new stuff would be hot when the truck was off. This would be a sure fire way for me to kill my battery.
How can I make the block be energized only when the key is on acc?

Thanks for any help. This may sound like a total newb question, but I just want to make sure I get it right on the first try.

Tyler

 

[HMR]

:lurk:

 

[Nullifier]

Why not put an inline switch to kill the lead going to the block at the fuse block?

 

[Robthebrit]

How much power are your aux devices taking? You probably can't find a high power acc switched source so I would get a 50A relay and wire the coil side to pretty much anything I could find that is switched with the ignition, hunt around the fuse box. Wire the power side of the relay directly to the battery via a master fuse or breaker and then on to your aux fuse panel.

In the future remove the relay and wire the fuse box directly to the aux battery. Given that the relay is already there you can get creative and use the relay to switch between aux power and main battery power allowing you to drive your aux devices from either battery.

One thing to remember when working with main battery power and aux is never conenct them together, the only place the batteries should ever connect is through the charge controller/isolator. If you do connect them something is going to get unhappy, there is probably a big charge difference between the batteries and they will equalize via anything that connects them and this can involve huge currents. However, do always connect the grounds.

Rob

 

[Northern Explorer]

Just off the top of my head...I would find a circuit running from the trucks stock fuse box that is shut off when the truck is off. I would then tap into this circuit to turn on and off a relay that could handle the high amp 8ga wire that is going to your auxilliary fuse box.

 

[Northern Explorer]

you beat me to it

 

[Michael]

Behind the rear seat in a D/C will work great -- but there is a very unobtrusive alternative that might be more convenient to your power loads. I mounted a 12VDC bus under the double cup holder in the center console on my 06 Tacoma Access Cab. The cup holder (the one with the adjustable arms) just pops out when you pull up on the straight edge. If it has never been removed, it might be a bit stiff. In that case, a putty knife with tape over the end makes a nice removal tool. In fact, a putty knife will take apart about 90% of your cab I agree with any switched power controlling a relay until you get your aux battery installed. If you have the bed 100/400W power plug, the factory inverter is located under the storage bin in your center console and that is heavy duty wire and switched. If you don't have it, it might be worth checking for the wiring harness anyway -- Toyota usually uses the same harness regardless of what options you buy. Blue Sea makes a nice bus bar (with a cover that protects against inadvertent shorting) that can be very securely mounted with double-sided tape. I powered the bus using 6 ga wire from the aux battery located in the bed (another post sometime). My goal was to have nothing except stock equipment (or less) running off the starter battery. As far as fusing, I have the bus feed fused in the back (rated conservatively for total desired load) and matched fuses on the individual loads (CB, 2m, GPS, AC inverter, DC plugs, etc.) I used a local ground with the same gauge wire that feeds the bus. I have zero ignition noise on the 2m, with some minor accessory noise on the CB (power windows, etc). Think lean and clean and it will fit under the cup holder without a problem.

This is the power panel at the back of the center console. The switches allow me to isolate the entire panel (top) or just the AC inverter (bottom). A tight fit but worth the effort. Darn, I just noticed that label is crooked ...

 

[Robthebrit]

Nice panel! Did you take a normal inverter to pieces and cram it in there somehow or is it just a short extension cable to a normal inverter?

Rob

 

[Willman]

Behind the rear seat in a D/C will work great -- but there is a very unobtrusive alternative that might be more convenient to your power loads. I mounted a 12VDC bus under the double cup holder in the center console on my 06 Tacoma Access Cab. The cup holder (the one with the adjustable arms) just pops out when you pull up on the straight edge. If it has never been removed, it might be a bit stiff. In that case, a putty knife with tape over the end makes a nice removal tool. In fact, a putty knife will take apart about 90% of your cab I agree with any switched power controlling a relay until you get your aux battery installed. If you have the bed 100/400W power plug, the factory inverter is located under the storage bin in your center console and that is heavy duty wire and switched. If you don't have it, it might be worth checking for the wiring harness anyway -- Toyota usually uses the same harness regardless of what options you buy. Blue Sea makes a nice bus bar (with a cover that protects against inadvertent shorting) that can be very securely mounted with double-sided tape. I powered the bus using 6 ga wire from the aux battery located in the bed (another post sometime). My goal was to have nothing except stock equipment (or less) running off the starter battery. As far as fusing, I have the bus feed fused in the back (rated conservatively for total desired load) and matched fuses on the individual loads (CB, 2m, GPS, AC inverter, DC plugs, etc.) I used a local ground with the same gauge wire that feeds the bus. I have zero ignition noise on the 2m, with some minor accessory noise on the CB (power windows, etc). Think lean and clean and it will fit under the cup holder without a problem.

This is the power panel at the back of the center console. The switches allow me to isolate the entire panel (top) or just the AC inverter (bottom). A tight fit but worth the effort. Darn, I just noticed that label is crooked ...

Very nice!

You need to do a build thread on your rig!

Welcome to the ExPo!

 

[buldyourown]

Thanks for all the replies. I do have the bed inverter. I bought another inverter for the cab and I feel silly now knowing that there is one under the center consul. Live and learn.

Anybody have any simple guide lines for wire size and correlating fuse size. This is really my first DC electrical project.

 

[Michael]

Nice panel! Did you take a normal inverter to pieces and cram it in there somehow or is it just a short extension cable to a normal inverter?

Rob

Rob,

I installed a 400W inverter (pseudo sine wave type) in its original case next to the automatic gear shift. Pep Boys sells a unit that has cooling fins integrated into the case. There is just enough room to put it on the passenger side using a tie wrap and some foam wedges to keep it from jiggling around. The DC power to the unit is from the forward DC bus (see earlier post) and the output plug was extended by means of a short length of power cord terminated at the AC plug on the rear of the console. You can hear the built-in fan when the inverter is running and it does make noise on the CB but no problems on the 2m/70cm dual band. I think I have a cheap CB I monitored the temp inside the console and no significant increase during 4 hours on the highway in normal lineup. 400W AC in the cab is plenty of power to run a small laptop and charge cell phones, camera batteries, etc. I also have an 800W inverter in the back camper area for bigger loads -- although I haven't tried blending margharitas back there... yet.

I did not interface with the factory inverter -- it is still "stock" and runs off the starter battery.

 

[Michael]

Thanks for all the replies. I do have the bed inverter. I bought another inverter for the cab and I feel silly now knowing that there is one under the center consul. Live and learn.

Anybody have any simple guide lines for wire size and correlating fuse size. This is really my first DC electrical project.

I wouldn't feel silly -- the factory installed inverter in the console is very limited in use and can't be used at all unless the engine is running. If you're going to have an aux battery some day, an inverter or two will come in very handy See previous post about one solution to install another inverter in the cab.

There are some good resources on the net on DC theory. Here is just one:
http://www.physics.uoguelph.ca/tutorials/ohm/index.html

As for wiring, there are quite a few places on the web that provide good info. Here is one of them: http://www.rbeelectronics.com/wtable.htm

This site has a number of useful references on wire sizing, voltage drop, etc:
http://bluesea.com/resources/7

And this site talks about how to figure out your fuse sizes.
http://www.interfacebus.com/mechanical_fuse.html

There are probably better ones around, I just grabbed those from my link folder.

Some unsolicited advice about truck wiring:
1. Use wire looms for anything you run under the chassis or under the hood. A short due to rubbing or vibration (can you say "off-road"?) will almost certainly ruin your day.
2. Make sure you get good connections on everything --when in doubt, solder it.
3. You can't go wrong using a larger wire size than you need, it just costs a bit more and is a ***** to run
4. Plan your fusing carefully -- your insurance company will appreciate it. Always put a fuse on both legs of any batteries in the circuit (and reasonably near the battery itself).
5. Be aware that all batteries can off-gas when charging, so don't put them in closed spaces. It is unlikely, but even AGM batteries will off-gas if you abuse them (like over-voltage charging them while running around the hot desert). If you want to enclose the battery, get the kind that has a vent port and attach a tube that goes outside.
6. Beware the evil ground loop -- make good ground connections, preferably to the chassis, not the seat brace.
7. Never take advice from strangers on the internet.

Good luck on your build!

 

[keezer36]

Thanks for all the replies. I do have the bed inverter. I bought another inverter for the cab and I feel silly now knowing that there is one under the center consul. Live and learn.

Anybody have any simple guide lines for wire size and correlating fuse size. This is really my first DC electrical project.

Fuse size will be dictated by the amperage draw of the accessory. If it is not already fused, you can calculate it by using Ohm's Law utilizing other avaliable info such as voltage and watts.
http://www.the12volt.com/ohm/ohmslaw.asp

Use the Wire Gauge Selection Table at the bottom of the page for wire size: http://www.rbeelectronics.com/wtable.htm

If you'd like to use a fuse block that already has a relay integrated with it, there is this one: http://www.amazon.com/Painless-Wiri..._1?ie=UTF8&s=automotive&qid=1197463148&sr=8-1 The 70207 has three constant hot and four ignition hot ckts. and can be mounted in the engine compartment if you wish as it is weather resistant (more so than the factory fuse block).

Your fuses in the engine compartment are all constant hot. Your ignition hot fuses are in the cab, behind that small drawer by your left knee.

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