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wiring for car-battery, fuse block, etc.

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Delivers1234

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So, I am not sure what type of fuse block to get and wire and switch.
I have a yaseu ftm-100, bearcat 980, and a driving cam (uses cigeratte lighter).

the fuses are 6 amps max. the yaesu has fuses on the black and red wires. i looked on ham radio and found MFJ MFJ-1104 DC Power Panels
http://www.hamradio.com/images_manuf/H0-013876A.jpg

I also looked at the 4 block anderson pole block. The block would be secured on the floor behind the main console. I'd like to run the negative and positive leads from the battery to the equipment. The fuse blocks i've seen only have a positive lead.

Wire size?
Type of fuse block with cover?
How do i connect the negative leads from the equipment to the battery lead?

Thank you.
 

mmckenna

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Anderson Power Poles are nice if you are moving radios around a lot, but in an automotive application where things are pretty fixed, they are kind of expensive and an overkill.
They are a nice product, though.

A cheaper, easier and perfectly acceptable product is something like this:
https://www.amazon.com/Bussmann-BP-15600-06-20-Quick-Connect/dp/B001BXKLNQ/ref=sr_1_14?ie=UTF8&qid=1479712226&sr=8-14&keywords=automotive+fuse+block

You can get similar items at auto parts stores or marine supply (We$t Marine).

I'd run an 8 gauge wire off your battery, through a 40 amp fuse/circuit breaker near the battery. From there, run the 8 gauge through the fire wall to the fuse block. Pick up a local ground, or run one from the battery in addition to a local ground.
From the fuse block, run your radios and accessories.

8 gauge wire in lengths likely to be run in your vehicle will support 40 amps without issue. This is more than enough for 2 amateur VHF/UHF radios transmitting at the same time with room to spare. That'll give you some growth room. For your current radio, CB and accessories, you'll have lots of capacity.
Fusing near the battery protects the overall system. The fuse block inside the vehicle gives you a good distribution point while protecting the individual circuits.

Some fuse blocks have a ground (-) connection buss, which can be handy. While running a negative lead from the battery is an option, using a local ground is, too. The benefit of a local ground (grounded to the body) is that you are providing a good RF ground as well as a power ground. It'll also save you a bit on wire. https://www.amazon.com/Blue-Sea-Blade-Block-Cover/dp/B001TXNY50/ref=sr_1_49?ie=UTF8&qid=1479712803&sr=8-49&keywords=automotive+fuse+block

Remember that your power ground and a good RF ground are two different things. Relying on a long wire run to the battery for your - connection can create RF ground issues. Just like relying on the long run to the point where the antenna coax is grounded at the mount. It's always a good idea to run a short piece of wire from the radio chassis to the vehicle body in addition to your power ground. This can sometimes fix weird issues, especially noise issues with CB's.

So, 40 amp fuse at the battery. I use one of these under the hood in my own truck:
https://www.amazon.com/Blue-Sea-Systems-MAXI-Block/dp/B000THTBZO/ref=sr_1_2?ie=UTF8&qid=1479713055&sr=8-2&keywords=Maxi+fuse+holder

8 gauge or larger to the distribution block inside the vehicle.

Use a 15 amp fuse for your Yaesu radio.
Use a 5 amp fuse for your CB
Probably a 3 amp fuse will work just fine for your camera. (you can add a cigar lighter plug to the distribution block to power this)
 

Delivers1234

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Anderson Power Poles are nice if you are moving radios around a lot, but in an automotive application where things are pretty fixed, they are kind of expensive and an overkill.
They are a nice product, though.

A cheaper, easier and perfectly acceptable product is something like this:
https://www.amazon.com/Bussmann-BP-15600-06-20-Quick-Connect/dp/B001BXKLNQ/ref=sr_1_14?ie=UTF8&qid=1479712226&sr=8-14&keywords=automotive+fuse+block

You can get similar items at auto parts stores or marine supply (We$t Marine).

I'd run an 8 gauge wire off your battery, through a 40 amp fuse/circuit breaker near the battery. From there, run the 8 gauge through the fire wall to the fuse block. Pick up a local ground, or run one from the battery in addition to a local ground.
From the fuse block, run your radios and accessories.

8 gauge wire in lengths likely to be run in your vehicle will support 40 amps without issue. This is more than enough for 2 amateur VHF/UHF radios transmitting at the same time with room to spare. That'll give you some growth room. For your current radio, CB and accessories, you'll have lots of capacity.
Fusing near the battery protects the overall system. The fuse block inside the vehicle gives you a good distribution point while protecting the individual circuits.

Some fuse blocks have a ground (-) connection buss, which can be handy. While running a negative lead from the battery is an option, using a local ground is, too. The benefit of a local ground (grounded to the body) is that you are providing a good RF ground as well as a power ground. It'll also save you a bit on wire. https://www.amazon.com/Blue-Sea-Blade-Block-Cover/dp/B001TXNY50/ref=sr_1_49?ie=UTF8&qid=1479712803&sr=8-49&keywords=automotive+fuse+block

Remember that your power ground and a good RF ground are two different things. Relying on a long wire run to the battery for your - connection can create RF ground issues. Just like relying on the long run to the point where the antenna coax is grounded at the mount. It's always a good idea to run a short piece of wire from the radio chassis to the vehicle body in addition to your power ground. This can sometimes fix weird issues, especially noise issues with CB's.

So, 40 amp fuse at the battery. I use one of these under the hood in my own truck:
https://www.amazon.com/Blue-Sea-Systems-MAXI-Block/dp/B000THTBZO/ref=sr_1_2?ie=UTF8&qid=1479713055&sr=8-2&keywords=Maxi+fuse+holder

8 gauge or larger to the distribution block inside the vehicle.

Use a 15 amp fuse for your Yaesu radio.
Use a 5 amp fuse for your CB
Probably a 3 amp fuse will work just fine for your camera. (you can add a cigar lighter plug to the distribution block to power this)


Thanks. Could 12 gauge work? What do u think of a relay/switch with a toggle switch?

So do I need a negative from the battery? I read about it and the use of a fuse. Also yaesu has fuses on the negative and positive.
 

jonwienke

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12-gauge wire will only handle about 20 amps safely. You don't want wiring running at or near its max capacity, voltage loss will affect performance, and the wiring will heat up.

I would run a negative and positive wire, and consider grounding the radio to the car body as well.
 

Rred

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"Could 12 gauge work?"
There are different ways to look at that. "Work" can mean "supply power without overheating and starting a fire". Yes, 12AWG probably would do that. Do note that 12AWG wire is also about the same thickness as 8SAE wire. AWG sizes and SAE sizes are not equal to each other, and anything you buy in an auto parts store, or anything that does not say "AWG" on it, probably is the thinner cheaper SAE size wire.

Now, besides fire safety there is another issue. Every wire has voltage drop, and the longer the wire and the higher the load, the more voltage drop there will be. You can find tables of voltage drop for 12-volt wiring online. Generally, a 2-3% drop is considered acceptable, but you might be surprised to find that if you have 30 feet of wire (you measure the length of the wiring run round trip, not just one way) carrying 30-40 amps, there's a lot more voltage loss than you thought.

So you may choose to use heavier wire in order to provide "full" voltage to your equipment, which makes the radio's perform better, not just because of fire safety.

When you see "ampacity" (safe carrying current limits) for wire, that's also usually based on 1 wire running in free space. In engine compartments or near exhaust systems, where it is way hotter than "room temperature", the ampacity of the wire is also de-rated, so again, you might want to look for wire with a suitable rating "for use in engine rooms and enclosed spaces" and petroleum-resistant, because all insulation is not equally well made.

Then there's a question of whether to use plain copper wire, or tinned copper wire. Tinned wire is more expensive, but it simply never punks out, turns green or black from corrosion. If you plan to keep using the wires, and they may be in a harsher environment (road dirt, moisture, etc.) it may pay to use tinned wire and just never worry about those problems.

A good source for "battery cable" and heavier tinned power wires in general can be Marine Wiring, Boat Cable and Electrical Genuinedealz.com, who can also professionally install terminal lugs and other fittings basically for just the price of the fittings. I'm not related to them, just one of many very happy customers.
 
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cmdrwill

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"Could 12 gauge work?" Yes, but make sure you do not get some chicom wire that has low temperature plastic insulation that WILL melt at higher current or high engine compartment temps. I have had to replace 'stereo shop' wire because it melted. And off shore wire seems to be much smaller that the gauge stated, ie 12 gauge may actually be 14 gauge or maybe 13 gauge .
BTW, I use 10 gauge stranded electrical wire and that has high temperature insulation for use in conduit, same stuff used in buildings.

FUSE at the battery terminal, 25 or 30 amp blade type. I put a fuse for each radio hot side, and ground the radio power near where the radio is mounted.

Battery--25A fuse-- 10ga wire to radio(s) location--- fuse for each radio hot----RADIO --ground
 

mmckenna

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Thanks. Could 12 gauge work? What do u think of a relay/switch with a toggle switch?

So do I need a negative from the battery? I read about it and the use of a fuse. Also yaesu has fuses on the negative and positive.
12 gauge would work fine for one radio. Since you'll be adding a CB, camera and maybe some future stuff, I'd really avoid it.
As stated above, the smaller cable will have reduced capacity and will introduce some voltage drop into the system. You really don't want that.

Since it's unlikely you'd be transmitting with the CB and the dual band radio at the same time, 12 gauge would be the absolute minimum, but I'd still go with something larger.
In reality, it's up to you. I wouldn't go small on the cable to save a few bucks. The real cost here is the time you'll spend doing the installation. If you cut corners on the materials, it might bite you later and end up costing more labor time.

A relay and a toggle switch is an option. I'd recommend putting the relay near the battery, just after the fuse.
Better yet, look at one of these:
Lind Electronics Shut Down Timer Model SDT1230-14 | eBay
These timers can be a good option. You wire them in to ignition and put it in your power feed. When you start your car, the power will go to the radios. When you shut off the car, it'll keep power on for a set length of time, then automatically shut everything off. This can be a real battery saver if you forget to turn things off.
I use one of these on my truck. I never have to touch the radios, they come on when I start, and run for about 15 minutes after I shut it off.

And, I'd probably agree, run a negative from the battery. You can use the chassis ground, but it relies on the grounding strap at your battery. Might be good, might not. Again, the real cost is in the labor, and you'll be running wire anyway, so just do it while you are under the hood.
 

wa1nic

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When talking about 12 volt systems, there is "what size wire is safe" and "what size wire is adequate"?

12 gauge is certainly safe, but if the run is too long the voltage drop will be too much.

You are only starting out with 13 or so volts, so loosing 1 volt on a 12 volt system is a bigger deal than looking 1 volt on a 115 volt system. Check wire charts and calculate the voltage drop for the length of wire you need.

It is best to run both + and - together as a twisted pair all the way to the battery.

If you want a source of "good wire", check out genuinedealz.com . They sell marine grade wire, which wont turn all green over time like more common automotive grade wire. They have lots of other things like switches and terminals and battery taps that are made for a marine environment - great for a solid install in automotive as well.
 

Delivers1234

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When talking about 12 volt systems, there is "what size wire is safe" and "what size wire is adequate"?



12 gauge is certainly safe, but if the run is too long the voltage drop will be too much.



You are only starting out with 13 or so volts, so loosing 1 volt on a 12 volt system is a bigger deal than looking 1 volt on a 115 volt system. Check wire charts and calculate the voltage drop for the length of wire you need.



It is best to run both + and - together as a twisted pair all the way to the battery.



If you want a source of "good wire", check out genuinedealz.com . They sell marine grade wire, which wont turn all green over time like more common automotive grade wire. They have lots of other things like switches and terminals and battery taps that are made for a marine environment - great for a solid install in automotive as well.


Grommets? Or the kind they use that r like rubber over the seals? Anyone know where to look?
 

W5SAB

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might not need grommets if you already got a rubber sealed passthrough already, just add a slight for the wires

Sent from my XT1585 using Tapatalk
 

KC4RAF

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Your Yaseu FTM-100 has a 50 watt on transmit. So using ohm's law, I=P/V, it would draw in the neighborhood of 3.7 amps or there abouts. So 12 gauge would be okay if the run isn't in a hot area or too long; you could use something like THHN or one of the SO wire. If you plan on adding other devices, I'd agree with mmchenna and use at least a number 10 stranded.
 

mmckenna

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Your Yaseu FTM-100 has a 50 watt on transmit. So using ohm's law, I=P/V, it would draw in the neighborhood of 3.7 amps or there abouts. So 12 gauge would be okay if the run isn't in a hot area or too long; you could use something like THHN or one of the SO wire. If you plan on adding other devices, I'd agree with mmchenna and use at least a number 10 stranded.
Good point, however transmitters are not 100% efficient, so it'll draw more than 50 watts on the DC power side. More like 10-12 amps depending on it's efficiency. I know that's what my Motorola draws at 45 watts transmit power.

The correct formula for figuring wire size is:
CMA = (A) x (LF) x (K)
------------------------------
(AVD)

CMA = Circular MIL area of the conductor
A = ultimate drain in Amperes
LF = Conductor loop feet (this is both the + and the - wire run)
AVD = Allowable Voltage Drop
K = constant factor for the wire. TW type commercial wire (not what you should be using) is 11.1

So, figuring on a 20 ampere (A) draw total, which would be good for the dual band transmitting, CB transmitting (you've got a passenger, right?) and the camera draw.

Total loop length would be somewhere around 30 feet, 15 feet for the +, 15 feet for the -. Might be a bit generous, but you can use up a lot of wire running around the dashboard, through the firewall and to the battery.

For the wire constant, let's just use the 11.1 constant (K) for TW wire (I know, you'll use something different, but for kicks.....)

Allowable Voltage Drop (AVD), lets go with 0.5 volts, which is generous, your radios will probably work fine with a 1 volt drop.

20 amperes x 30 feet x 11.1 = 6660
AVD = 0.5

6660 x 0.5 = 13,320 circular mils wire conductor area.

That is roughly 8 gauge wire. Actually, it's between 10 ga and 8 ga, but you are not going to find a 9 gauge wire.

8 gauge would be the minimum I'd run. 6 gauge would be a good choice if you were going to add a second radio, but by then you are getting into the area where you won't have enough hands/people to transmit with that many radios at once.
 

SteveC0625

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Your Yaseu FTM-100 has a 50 watt on transmit. So using ohm's law, I=P/V, it would draw in the neighborhood of 3.7 amps or there abouts. So 12 gauge would be okay if the run isn't in a hot area or too long; you could use something like THHN or one of the SO wire. If you plan on adding other devices, I'd agree with mmchenna and use at least a number 10 stranded.


Ohm's Law doesn't work on rf power ratings. You have to have the current draw info from the manufacturer's specs on the radio.

I had a new ham who was asking about fusing a radio. I gave him the correct fusing of 15 amps for the 25 watt version of the radio. He ignored my information and applied Ohm's Law to the rf wattage of the radio, arriving at a fusing of 3 amps. He could not understand why he was blowing fuses as soon as he keyed the mic.

EDIT TO ADD: I finally found the specs on this radio. It's rated at an 11 amp draw at 144 Mhz and 12 amps at 440 MHz. I also noticed that several of the online vendors are offering power supplies with this radio that are all rated up around 20 amps or better.

For the OP, if you are running a main power cable from the battery to a fuse box and planning to run multiple items from there, consider 8 AWG or larger. When we do police cars or EMS fly cars, we generally use even larger wire to feed a remote power point in the vehicle.

For really good info on upfitting cars and trucks with radios, lights, sirens, etc. check over at elightbars.org. It's where all the pro upfitters hang out.
 
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I'd honestly cut the fuses off the negative leads and just run them to chassis ground. Most Japanese engineered radio equipment calls for negative fused with the lead going direct to the battery. It's not something you see a ton in production though. Most shops install using the fused positive lead, chassis ground method.
 

mmckenna

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Ok. Thank you all. I got the 8 gauge, the block. what do you all think about this https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A
That will work. Before you purchase that, check into the price and availability of replacement fuses. Just in case you do blow the fuse, make sure you know how much the replacement is. That's sort of an odd fuse type, and finding a replacement might cost more and take longer.

I use something similar to this in my own truck. It's mounted near the battery with a 60 amp fuse protecting the 6 gauge power feed running to the back of my truck cab:
https://www.bluesea.com/products/5006100/MAXI_Fuse_Block

Nice thing about those is that the Maxi fuses are cheap and you can pick the up at any automotive parts store. You can get those fuse holders at West Marine. There's one over in Seaside, just a short hop for you.



for + and - at the battery as fuses. I think its easier than going cutting the wires etc..I would put 30 amp fuses.
You don't need to fuse the - power lead at the battery. Since the vehicle body is already at ground potential, just like the - lead, there really isn't any need to.

If you chose to keep the fuses on the - lead for the radio, that's up to you. Opinions will vary and there are some good reasons for keeping it or removing it. I tend to roll with whatever the manufacturer recommends. Proper installation techniques eliminates the need for a fuse on the negative lead, but it won't hurt having one in there.
 

wa1nic

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The fuse in the negative lead can actually be important.

In just about all cars there is a braided strap that runs from the engine block to the chassis. If that strap ever deteriorates, starter motor current can flow instead thru the negative lead of your radio and out thru the coax braid to wherever you have grounded your antenna. Without a fuse, there can be a fire.
 

prcguy

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Lots of good advice running a larger 8ga wire for future equipment, the cost of the wire is small compared to the effort of upgrading later. Instead of a fuse near the battery I like to use circuit breakers in vehicles because you can accidentally blow a fuse and have no spare when you need the radio the most. Here are a couple of circuit breakers that should be ok to install under the hood near the battery:
Audiopipe IPMB40A Marine 40 Amp Circuit Breaker | eBay

Car Auto Marine Inline Circuit Breaker 40 AMP Manual Reset Audio Fuse Holder

Here is a fuse block to go under the dash for connecting the radios and there are circuit breaker versions available also: MARINE 6 GANG QUICK CONNECT TERMINAL BLADE AUTO FUSE PANEL HOLDER WITH BOLTS | eBay

On fusing the ground lead(s) I think the chances of your battery ground cable coming loose and causing starter current to flow in your radio leads is very unlikely in a modern vehicle. I have never met anyone who had this happen but I know 2 people that have been hit by lightning and one is dead. My opinion is you have better chances of being hit by lightning than hurting your radio or its ground lead from a failed battery cable.

The few times I've measured voltage drop to a 100w class radio the negative lead fuse accounted for nearly half the voltage drop. If your battery ground lead failed you would know instantly when you try to start the car as all the lights would dim severely and the starter would barely crank. I think most people would sense something is wrong in the first turn of the key and investigate before damaging anything.
prcguy
 
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