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subzali
03-20-2008, 09:28 AM
I'm looking at adding an auxiliary fuse block for things like my CB, Ham, and lights. I got a '77 fuse block the other night that I thought I could use, but I don't know what to do with it. I figure I can mount it somewhere inside the cab and then run power from the battery to it. There's so much I don't know though. How do I get a clean lead attached to the battery? Do I need a new battery terminal connector? Is there only one lead to the fuse block to provide power and then the individual circuits branch off of that? Or do you have to run individual leads to the fuse block from the battery? What about trying to get a clean power source for the radios to reduce engine interference? Should I use coax or some other type of shielded cable? If so, how do I run the sheath to ground?

I figure once I get the fuse block mounted then I can figure the rest of it out pretty easily, it's only fuses and wire at that point :D

timmbuck2
03-20-2008, 10:58 AM
I bet Romer will chime in here. I checked out his setup on his 80 a couple of weeks ago. very slick. I bet hewill post pics. :)

t

nuclearlemon
03-20-2008, 02:27 PM
on the advice of m.a.d. enterprises, i have a junction block that i run the alternator wire to and then run wires off it to a block or an accessory. you get better power that way.

Corbet
03-20-2008, 03:06 PM
Pretty much same question here.

I know my HAM directions say to connect directly to the battery. I'd really prefer to run it to my fuse block under the passenger seat, rather than have multiple leads connected to the battery. Plus just another thing to have to get through the firewall.

Hulk
03-20-2008, 03:48 PM
I mounted a new auxiliary fuse box to the firewall on both my 40 and my 80. I ran a fairly thick cable directly to the positive battery terminal. On my 40, I got a new terminal for the battery that has a large stud with a wingnut. All my cables now mount directly onto this stud.

Corbet, I ran the power to my ham radio from my aux fuse box. It's always on, so the unit maintains power whether the ignition is on or not. Maybe this is the reason the manufacturer wants you to run power directly from the battery.

Uncle Ben
03-20-2008, 04:15 PM
Power will stay clean as long as it's a dedicated circuit from the power source. You can add circuits to that feed as long as they are not inductive. Always match wire resistance to amp load. To figure amp load take the wattage of your accessories divided by 12 (volt) to get amps. There are tables all over to tell you the amp load capacity of a given lead vrs distance. I'm sure Yota or Romo will chime in with the formula for figuring that but finding a chart works for me. Also, never coil excess wire or run it by anything that would generate high frequency interference(anything with coiled wire :rolleyes:).

Corbet
03-20-2008, 04:38 PM
Corbet, I ran the power to my ham radio from my aux fuse box. It's always on, so the unit maintains power whether the ignition is on or not. Maybe this is the reason the manufacturer wants you to run power directly from the battery.

This is taken from the instruction manual

"Route the DC power cable supplied with the transceiver directly to the vehicle’s battery terminals using the shortest path from the transceiver."

Maybe worried about voltage drop? The wiring supplied has no apparent "shielding" of any type. Adding 3' to the power supply path should not effect my voltage drop much as the larger gauge wire supplying the fuse block should make up for any addition resistance due to length.

You can add circuits to that feed as long as they are not inductive.

Define "inductive"

Uncle Ben
03-20-2008, 04:52 PM
This is taken from the instruction manual

"Route the DC power cable supplied with the transceiver directly to the vehicle’s battery terminals using the shortest path from the transceiver."

Maybe worried about voltage drop? The wiring supplied has no apparent "shielding" of any type. Adding 3' to the power supply path should not effect my voltage drop much as the larger gauge wire supplying the fuse block should make up for any addition resistance due to length.



Define "inductive"


Anything that has a armature.

Corbet
03-20-2008, 05:23 PM
Anything that has a armature.

So as long as the HAM radio does not share its power supply with anything with an electric motor or generator? How isolated does it need to be? We all have heater blowers and wiper motors. Will they cause interference if running? Does an Engel/ARB fridge have a motor?

Uncle Ben
03-20-2008, 05:30 PM
So as long as the HAM radio does not share its power supply with anything with an electric motor or generator? How isolated does it need to be? We all have heater blowers and wiper motors. Will they cause interference if its running? Does an Engel/ARB fridge have a motor?

Your heater and wipers have their own curcuit so unless you tap into that circuit you will stay clean. My fridge, inverter and Ham share a dedicated power line but the #4 welding cable that feeds that load center is distributed from a clean junction box. Basically, diodes and shielding that prevent back feed. So to answer your question....if you run a lead back and daisy wire the fridge and Ham together on that same lead, yes, you will hear your fridge when it's running. Break that lead up in a load center and you ham power should stay clean.

Hulk
03-20-2008, 05:39 PM
...clean junction box. Basically, diodes and shielding that prevent back feed.

Cool. Where did you source this? I may want one of these if/when I get a fridge.

Corbet
03-20-2008, 05:51 PM
Break that lead up in a load center and you ham power should stay clean.

OK, define and or describe a "load center"

DaveInDenver
03-20-2008, 06:37 PM
Note that EMI or RFI is not just inductive, it can be from any reactive source. A motor (or alternator) is one source, interference or any other sort of switching noise could be from a device power supply (iPods, radios, cell phones, GPS) or computer. Clean power is not just noise, but voltage levels, too. So there's a few things to think about.

Diodes are one part of a filter, although what they will do for you sort of depends on where they are used. Certainly useful as a rectifier, voltage regulator or isolation.

There are a few key things you want to remember when wiring things in your truck.

-First and foremost is to use sufficiently sized wires and fuses and use termination (crimps, lugs, screws, bolts) that is clean, free of oxidation and mechanically solid.
-When dealing with something that is sensitive to noise, primarily radios and such, the positive and negative leads should be the same length and run as close together (if they are split) as possible. Being the same length is very important.
-Never run power leads in parallel with signal leads (i.e. don't bundle power wires and antenna coax), cross them at 90 degrees and keep at least a few inches of separation between them otherwise.
-Extra lengths of wire and cable should not be coiled, but make them into bow tie, like a loose coil squished in the middle. Best is to cut coax to length, followed by just loosely organizing it and tucking it away.
-Final grounds should only either be at the battery or the frame. You can run a local ground if it's very low impedance to ground. IOW, a ground lug inside the cab that is then grounded directly to the battery with a heavy cable. If you do this, then ideally you will have a matching positive lug with the same sort of connection to the battery, too.
-Consider a filter on sensitive power (this is just as simple as a capacitor and inductor).

In most cases a filter should not be necessary if you just follow sound wiring practices. Never start with a filter as a solution because it will probably only band aid a problem and eventually the noise will get so bad that a filter won't work anymore. For example, often the reason people get alternator or ignition noise is because of a problem with the alternator or ignition. Fix the problem (i.e., new brushes, new plug wires, etc.) and the problem will be much reduced. Wiring that is too small, which causes abnormally high voltage drops can make things more sensitive to noise and just getting wiring that is big enough to handle the load will help a ton.

If after checking your wiring and electrical system you still have noise issues (you won't, I guarantee it), then add a filter. If this is the case then you are probably either a big time car audio or mobile HF ham anyway and probably know a lot of this.

nuclearlemon
03-20-2008, 08:07 PM
OK, define and or describe a "load center"

i'm guessing a fuse block or something similar.

Rzeppa
03-21-2008, 10:50 AM
I'm looking at adding an auxiliary fuse block for things like my CB, Ham, and lights. I got a '77 fuse block the other night that I thought I could use, but I don't know what to do with it. I figure I can mount it somewhere inside the cab and then run power from the battery to it.

That's precisely what to do with it, except there is an issue which is specific to 40s if you connect it directly to the battery, see below.

How do I get a clean lead attached to the battery?

That is not a good idea on a 40 due to the way 40s have the amp meter in series. Whenever you power a load directly from the battery instead of main vehicle system power, the amp meter will indicate that the battery is drawing power (being over-charged). Wiring techniques that apply to wagons (*J60s and up) are different than those for 40s for this reason! *J60s, 80s, etc. use a voltmeter instead of an amp meter.

You are better off simply using system power that is already there, certainly for small loads like your electronics.

Do I need a new battery terminal connector? Is there only one lead to the fuse block to provide power and then the individual circuits branch off of that?

No, an FJ40 fuse block will have two power sources: switched (only powered when the key is on) and unswitched (powered all the time). Headlights, horn, cigarette lighter etc. fall into the latter category. You can mount your aux fuse block near the existing one and draw power from the feeds to either switched or unswitched. I mounted my aux fuse block on the firewall above and to the right of the throttle pedal, just inside the tranny hump.

Or do you have to run individual leads to the fuse block from the battery? What about trying to get a clean power source for the radios to reduce engine interference? Should I use coax or some other type of shielded cable? If so, how do I run the sheath to ground?

As Dave mentioned, usually that is not necessary, and when it is, it is usually caused by the source of the noise (electrical interference) being excessive. If you do have any noise issues, they can easily be suppressed by adding an inductor in series at the load, and/or a small capacitor across the load. This creates a single pole low pass filter. Alternatively, you can try to locate and correct the source of the noise, however this is not always as easy to do.

I figure once I get the fuse block mounted then I can figure the rest of it out pretty easily, it's only fuses and wire at that point :D

What I did was create an entire isolated aux electrical system with a second battery (marine, deep cycle). That way I could run my extra loads without pulling power back through the amp meter. A wiring diagram is on my web site (sig line below) in the tech tips section.

subzali
04-09-2008, 08:50 AM
Wow, I wonder why I didn't see your response earlier Jeff! Thanks so much! I looked at what I had going last night and I think I might have to move to plan B. Haven't figured out what plan B is yet, so that'll be fun since I'm 2 1/2 weeks away from being unable to participate in Moab because of not having a functional radio. I need to look at the wiring diagram more closely to see where I can tie in power (and do it so it's clean) - I forgot about the ammeter, and that is going to be a little bit of a challenge I think. I didn't really find a good way to mount the fuse block I have (plus it confused me), so I need to find a different fuse block somewhere that fits my needs better.

Got my FT-7800 last night though and got my antenna mounted and the coax traced to the Tuffy where the radio will be installed! :thumb:

In addition, gotta move my CB to the dash and power it up!

EDIT: I can't find Drew's Blue Sea fuse block info, but can someone look at these fuse blocks from Blue Sea (http://bluesea.com/category/5/21/products/5018) and tell me how to work these things? I'm so electronically stupid, I don't even know what I would do with this thing once I got it. I figure I would bolt it on the firewall, that I can figure out, it's mechanical. But beyond that I have no clue. Seriously. With or without negative bus? Would I have to wire each circuit separately? If so HOW do I tie in to vehicle power post-ammeter so that I don't screw up the charging system or other electrical systems on my truck? I mean seriously I'm used to using butt connectors, and those little splicing connectors that you fold over and they break the sheath of the two wires and voila! you have tapped into a wire.

RockRunner
04-09-2008, 09:17 AM
That was the one I was looking at. I need to get power to the back of my truck for my fridge and other things. I am want to run only a hot wire to the fuse block and ground the items to a grounding block/point.

One problem I have is finding a nice 12V plug in. I thought I found a good one but it turned out to be junk and I send it back.

Plan is to install the fuse block under the dash somewhere and run the CB, Radio and Ham in the future of it. Then run a big line to the rear for a two/three power port.

IF I HAVE TIME BEFORE Moab!!:eek::eek:

Rzeppa
04-10-2008, 09:01 PM
Wow, I wonder why I didn't see your response earlier Jeff! Thanks so much! I looked at what I had going last night and I think I might have to move to plan B. Haven't figured out what plan B is yet, so that'll be fun since I'm 2 1/2 weeks away from being unable to participate in Moab because of not having a functional radio. I need to look at the wiring diagram more closely to see where I can tie in power (and do it so it's clean) - I forgot about the ammeter, and that is going to be a little bit of a challenge I think. I didn't really find a good way to mount the fuse block I have (plus it confused me), so I need to find a different fuse block somewhere that fits my needs better.

Got my FT-7800 last night though and got my antenna mounted and the coax traced to the Tuffy where the radio will be installed! :thumb:

In addition, gotta move my CB to the dash and power it up!

EDIT: I can't find Drew's Blue Sea fuse block info, but can someone look at these fuse blocks from Blue Sea (http://bluesea.com/category/5/21/products/5018) and tell me how to work these things? I'm so electronically stupid, I don't even know what I would do with this thing once I got it. I figure I would bolt it on the firewall, that I can figure out, it's mechanical. But beyond that I have no clue. Seriously. With or without negative bus? Would I have to wire each circuit separately? If so HOW do I tie in to vehicle power post-ammeter so that I don't screw up the charging system or other electrical systems on my truck? I mean seriously I'm used to using butt connectors, and those little splicing connectors that you fold over and they break the sheath of the two wires and voila! you have tapped into a wire.

Those stoopid little folding splicing connectors is what Tim's Binder was choking on and caused him major flashinsparks. Bad joo joo. We danced around in the snow and drove off the little bugger evil spirits of flashinspark.

It's simpler than what it sounds like you're thinking. For your (relatively) low-draw electronics you can simply connect a wire on the upstream feed of your existing fuse block to the upstream side of your new fuse block, once you decide where to mount it. You can choose switched through the ignition switch, or unswitched directly from the regulator.

If you want high-draw items like lights and big stereo power amps, then you're talking a different kind of wiring on a 40. It can be done, but the stock alternator is only 40 amps (45 amps with the stock upgrade), so if you need to run big loads you need to consider upgrading the alt and/or battery(ies).

DaveInDenver
04-10-2008, 09:18 PM
Those stoopid little folding splicing connectors is what Tim's Binder was choking on and caused him major flashinsparks. Bad joo joo. We danced around in the snow and drove off the little bugger evil spirits of flashinspark.

It's simpler than what it sounds like you're thinking. For your (relatively) low-draw electronics you can simply connect a wire on the upstream feed of your existing fuse block to the upstream side of your new fuse block, once you decide where to mount it. You can choose switched through the ignition switch, or unswitched directly from the regulator.

If you want high-draw items like lights and big stereo power amps, then you're talking a different kind of wiring on a 40. It can be done, but the stock alternator is only 40 amps (45 amps with the stock upgrade), so if you need to run big loads you need to consider upgrading the alt and/or battery(ies).
Whoever put the trailer harness on my truck used those snap dealies to tap into the stock harness. I lost my tail lights and plate lamp because of the corrosion. Those things were invented by Satan himself I think.

The only thing he's got that's relatively high draw will be his ham radio. The FT-7800 at full TX power draws about 8 amps. I used 10AWG wire to power mine, to keep the voltage drop to a minimum. Shouldn't be too much of stress on the electrical system due to the minimal time you're actually transmitting, but it's not a bad idea to consider the biggest wire that is practical none-the-less.

Rzeppa
04-10-2008, 09:50 PM
Whoever put the trailer harness on my truck used those snap dealies to tap into the stock harness. I lost my tail lights and plate lamp because of the corrosion. Those things were invented by Satan himself I think.

LOL! No kidding! They are fine for an application that sees no (appreciable) current, no water, mud, dust, vibration or mag chloride. For automotive applications they suck BAD!

The only thing he's got that's relatively high draw will be his ham radio. The FT-7800 at full TX power draws about 8 amps. I used 10AWG wire to power mine, to keep the voltage drop to a minimum. Shouldn't be too much of stress on the electrical system due to the minimal time you're actually transmitting, but it's not a bad idea to consider the biggest wire that is practical none-the-less.

Cool! Intermittent high-draw won't require a huge alt or batt upgrade. Stock system wiring between the regulator and the fuse block on a mid 70s 40 is around 10 AWG anyway IIRC, and the TX will likely have a nice size cap at the power input anyway. If it were my rig I'd just wire it in and be happy. You can always come back and add a parallel conductor between the downstream side of the amp meter (regulator side) and the new circuit instead of tapping off the one that connects the amp meter to the regulator. It's only a couple feet max so it's not a huge deal anyway.

Show of hands: "Who just LOVES working under a dash, any dash?".

Darn, where'd everybody go?