wiring for car-battery, fuse block, etc.

[SteveC0625]

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

for + and - at the battery as fuses. I think its easier than going cutting the wires etc..I would put 30 amp fuses.

I'm with mmckenna on this fuse choice. Better to use a fuse that you can easily locate a replacement. Much better to use ATO or ATC fuses which are readily available most anywhere. Using a specialty fuse like the one suggested is going to be a problem to replace if it blows. And, at $26 each, you can buy an awful lot of heavy duty ATC holders and fuses.

Besides, the BlueSea and Buss fuse blocks use ATC's as well. Again, inexpensive fuses and easily located if you need a replacement.

 

[SteveC0625]

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.

I've done commercial and public safety radio installs most of my adult life. None of the radio manufacturers fuse the ground lead. If this supposed danger existed, I'm pretty sure that they'd supply power cables with both leads fused. They don't. This fused ground lead thing seems to be a ham radio thing. I'm not sure how it got started, but it's an unnecessary practice.

The manufacturers do, however, specify that the ground lead be connected to a factory grounding point near the battery. In today's modern vehicles with computer controlled power monitoring and control systems.,the negative battery post is where they place one of the computer's sensor leads. If you connect a radio (or other aftermarket item like lights or sirens) to the negative post, you'll interfere with the computer's data and behavior. If you connect to a factory chassis grounding point, the computers are unaffected.

The other equally important reason to connect to the chassis grounding point instead of the negative battery post is to prevent the possibility of a ground loop.

 

[k9wkj]

i would recommend at low volts disconnect if no ine else has mentioned it.

especially if you have a Yaesu ft-2600 uggggg
darn thing has gotten worse over the years
cant even transmit at all with out the engine running any more

 

[mmckenna]

This fused ground lead thing seems to be a ham radio thing. I'm not sure how it got started, but it's an unnecessary practice.

I agree, I've only ever seen this come up with amateur radio operators, never on the commercial side.

I think it's an "if I over engineer it enough, I can claim to be better than thou" thing.

Other than voltage drop through the fuse, it won't hurt anything to have one, but it's an unnecessary expense. If it really makes someone feel better to have one, then go ahead.
I've used fused negative leads back when I still ran amateur grade equipment, simply because it was there and it was easier to just leave it in place.
When I switched to all commercial grade radios, none of them included them. I didn't go out of my way to install them.

Anyway, any amateur radio operator that relies on their mobile radios for whatever "emcom" races, emergency prep, "when all else fails" should really be taking better care of their vehicles. Letting your negative battery lead corrode to the point it fails indicates a much bigger issue with knowledge, preparedness and common sense.

 

[Delivers1234]

I agree, I've only ever seen this come up with amateur radio operators, never on the commercial side.



I think it's an "if I over engineer it enough, I can claim to be better than thou" thing.



Other than voltage drop through the fuse, it won't hurt anything to have one, but it's an unnecessary expense. If it really makes someone feel better to have one, then go ahead.

I've used fused negative leads back when I still ran amateur grade equipment, simply because it was there and it was easier to just leave it in place.

When I switched to all commercial grade radios, none of them included them. I didn't go out of my way to install them.



Anyway, any amateur radio operator that relies on their mobile radios for whatever "emcom" races, emergency prep, "when all else fails" should really be taking better care of their vehicles. Letting your negative battery lead corrode to the point it fails indicates a much bigger issue with knowledge, preparedness and common sense.

The yaesu ftm 100 has a negative and positive fuse.

I'll look for I chassis point under the dash near the fuses.

 

[mmckenna]

The yaesu ftm 100 has a negative and positive fuse.

I'll look for I chassis point under the dash near the fuses.

Right, most amateur radios do. That isn't a bad thing, and it's OK to use them. The discussion above was wether it was necessary to add them to a master power feed.

Either way, local ground is a really good idea. Even if you run a dedicated negative power lead to the battery. There are a couple of types of grounding you need to consider:
-Safety Ground, this is similar to what hour household outlets have. It's there for protecting the people.
-DC Power ground. It the case of a vehicle, the - lead is also grounded. The entire vehicle body is ground, and thus connected to the battery.
-Signal/RF ground. These are there to help deal with noise, interference, etc.

Often people will get them confused, and while they are similar, they are not the same.
Having a local signal/RF ground for your radio is a really good idea. Since long wire runs can actually pick up interference from the other systems in a car, you don't want to rely on the negative lead going to the battery, or the shield of the coax, as your only grounding sources. Having the chassis of the radio connected directly to the vehicle body can give a path for stray RF, noise etc. a place to go. It can actually solve/prevent a number of common issues. It's easy to do, but many ignore it.

So, negative lead to the battery (or more accurately where the battery negative post is grounded to the body) is a good idea. A local ground to the radio chassis, usually one of the mounting screws if there isn't a dedicated grounding point, is a real good idea.

 

[wa1nic]

Besides marine grade wire, Marine Wiring, Boat Cable and Electrical Genuinedealz.com

carries both the Bluesea terminal blocks and also the replacement fuses, at about 33% off list price.

Be aware that the Bluesea fused terminal blocks mentioned previously do not come with fuses. Those need to be selected for ampacity and ordered separately.

Those blocks should not be considered radio protection, but are rather to protect against fire if your 8 gauge feel line shorts to ground. If you blow a 300 amp fuse, there is a serious problem. There are also smaller sized fuses for those blocks. Put in a fuse that the heavy wire can safely handle. A smaller fuse rated for the radio goes on the other end where the radio is located to protect the radio itself.

 

[jim202]

The fuse in the negative lead can actually be important.

In just about all vehicles 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.

You make the statement that there is a braided strap that runs between the engine block and the chassis. Which I have no problem with. But then you go on to say that if the strap goes bad, current can flow through the negative lead of your radio and out through the coax.

Before we go any further, please explain how the current can flow from the engine block and starter motor back through the radio and antenna coax if the ground strap on the engine goes bad. Last time I looked under the hood, if that strap goes bad, your starter won't work.

You need to explain to the group here just how the engine block can get a ground through your radio from the starter motor. Be specific just where this current path comes from. Remember you said the ground strap from the vehicle frame to the engine has gone bad. Where is the ground path from the engine coming from? The engine is mounted on rubber motor mounts, the exhaust is supported by insulated vibration straps, the radiator hoses are an insulator, the heater hoses are an insulator, the fuel line has a flexible section at the motor that is insulated, the drive shaft is not a good conductor, the auto transmission lines go to the radiator that generally is supported in an insulated bracket to allow for some movement. I just don't find any high current path between the engine and the frame of the vehicle except the flex braided strap your talking about.

I have been in the two way radio field for many years and have not seen the major radio companies installing a fuse in the negative wire from any of them except the off shore vendors. Even on the large trucks and fire engines, this is not done or causes a problem with the commercial radios. If there was a problem, we would have seen a fuse way back when RCA was still in the two way business.

 

[SteveC0625]

Just a small point, but it bolsters the position that the battery to ground strap failure is very remote.

Most new vehicles are now using heavy gauge stranded wire with a thick insulating jacket and high quality crimped on lugs at both ends instead of uninsulated heavy braided wire. Some of them even have heat shrink over the crimp and lug, effectively blocking much of the moisture that might reach the wire.

I live in the northeast where winter road salt is a constant issue. If any place in the US is going to see significant rates of failure in this wiring, it would be us and we don't. Truck and auto manufacturers have actually learned how to build vehicles that will withstand real life road conditions for many years.

I really think this whole ground strap failure thing is not any where near the issue that some might want us to believe.

 

[Project25_MASTR]

You make the statement that there is a braided strap that runs between the engine block and the chassis. Which I have no problem with. But then you go on to say that if the strap goes bad, current can flow through the negative lead of your radio and out through the coax.

Before we go any further, please explain how the current can flow from the engine block and starter motor back through the radio and antenna coax if the ground strap on the engine goes bad. Last time I looked under the hood, if that strap goes bad, your starter won't work.

You need to explain to the group here just how the engine block can get a ground through your radio from the starter motor. Be specific just where this current path comes from. Remember you said the ground strap from the vehicle frame to the engine has gone bad. Where is the ground path from the engine coming from? The engine is mounted on rubber motor mounts, the exhaust is supported by insulated vibration straps, the radiator hoses are an insulator, the heater hoses are an insulator, the fuel line has a flexible section at the motor that is insulated, the drive shaft is not a good conductor, the auto transmission lines go to the radiator that generally is supported in an insulated bracket to allow for some movement. I just don't find any high current path between the engine and the frame of the vehicle except the flex braided strap your talking about.

I have been in the two way radio field for many years and have not seen the major radio companies installing a fuse in the negative wire from any of them except the off shore vendors. Even on the large trucks and fire engines, this is not done or causes a problem with the commercial radios. If there was a problem, we would have seen a fuse way back when RCA was still in the two way business.

In a commercial grade antenna install, (i.e. NMO on the roof) the shield of the coax will end up being grounded to the chassis. Just how NMO (and actually most mobile antenna) mounts work.

So by grounding the negative lead directly to the negative post you create a ground loop when you connect your antenna to the radio. If the chassis ground strap were to fail current still has a path to ground as it can travel down the coax shield, across the radio and down the negative lead to the battery. This is where that fuse on the negative post becomes extremely important as it will blow and hopefully blow quick enough to keep the radio from being damaged.

Now, the real negative to using the negative post for the negative lead of the radio is the negative fuse can blow but the radio will still semi-function as it can still ground through the coax.

Sent from my SM-T350 using Tapatalk

 

[Delivers1234]

In a commercial grade antenna install, (i.e. NMO on the roof) the shield of the coax will end up being grounded to the chassis. Just how NMO (and actually most mobile antenna) mounts work.

So by grounding the negative lead directly to the negative post you create a ground loop when you connect your antenna to the radio. If the chassis ground strap were to fail current still has a path to ground as it can travel down the coax shield, across the radio and down the negative lead to the battery. This is where that fuse on the negative post becomes extremely important as it will blow and hopefully blow quick enough to keep the radio from being damaged.

Now, the real negative to using the negative post for the negative lead of the radio is the negative fuse can blow but the radio will still semi-function as it can still ground through the coax.

Sent from my SM-T350 using Tapatalk

I think the terminal fuse is easier for me to use. It sounds rare for the fuse to pop. Does any one know the post size for the 2013 equinox?

 

[N0ZQR]

On the order of fusing, which is "better", a circuit breaker or a fuse at the battery.

I've been told that a circuit breaker does not "like" the heat of an engine compartment where a fuse is
more "tolerant".

Ron

 

[prcguy]

A fuse or circuit breaker near the battery is a catch all for anything that can happen including shorting out the main cable from the battery. You usually use a very large value of fuse or circuit breaker compared to what the individual equipment will use like 40A, 60A for most installs.

A large value circuit breaker should not have a problem in a hot environment since the current draw through it will only be a fraction of its rating. Not like using a 20A breaker for a radio that draws 18A and excessive heat may change its break point where 18A could be a problem.

In my current vehicle I have a 250A fuse at the battery and 2ga wire running to a distribution box under my rear seats. I would rather use a circuit breaker at the battery but all I had at the time was the large fuse. Even though my equipment can draw close to 100A I don't believe a 250A breaker would change its break point enough to be a problem. Someday I'll track down a suitable 250A breaker and swap out the fuse.
prcguy

On the order of fusing, which is "better", a circuit breaker or a fuse at the battery.

I've been told that a circuit breaker does not "like" the heat of an engine compartment where a fuse is
more "tolerant".

Ron

 

[mmckenna]

I think the terminal fuse is easier for me to use. It sounds rare for the fuse to pop. Does any one know the post size for the 2013 equinox?

Probably 6mm x 1. Most of the newer GM's I've installed in are.

 

[jim202]

In a commercial grade antenna install, (i.e. NMO on the roof) the shield of the coax will end up being grounded to the chassis. Just how NMO (and actually most mobile antenna) mounts work.

So by grounding the negative lead directly to the negative post you create a ground loop when you connect your antenna to the radio. If the chassis ground strap were to fail current still has a path to ground as it can travel down the coax shield, across the radio and down the negative lead to the battery. This is where that fuse on the negative post becomes extremely important as it will blow and hopefully blow quick enough to keep the radio from being damaged.

Now, the real negative to using the negative post for the negative lead of the radio is the negative fuse can blow but the radio will still semi-function as it can still ground through the coax.

Sent from my SM-T350 using Tapatalk

Your not paying much attention to what I said in my last post. Modern commercial radios don't go back to the battery post for their negative. They use the vehicle frame. The fact that NMO mounts are grounded at the sheet metal they are mounted on, is not the issue. The vehicle roof or fender is part of the vehicle frame. The radios are grounded to the same vehicle frame.

Can't control what the off shore radio companies do, but the US radio companies don't run a negative wire from the radio to the battery for good reason.

As SteveC0625 has pointed out, most of the new vehicles have done away with the braid and gone to a heavy wire from the battery negative post to the vehicle engine. This path carries the heavy starter motor current. There is no high current path from the vehicle frame to the engine other than this heavy wire path.

You need to understand how current flows in vehicles from the battery to the starter motor. The old wife's tale of the radio to coax to antenna mount needs to be put to bed. Back in the old days of positive grounds and floating ground circuit boards in radios, I may have given you an ear for part of the conversation, but it doesn't hold water today.

 

[Rred]

A conventional circuit breaker "at" a battery, as the battery primary interrupt device, violates just about every electrical safety code or standard.

The reason being that conventional "12 volt" breakers are rated for about a 3000 amp current, and at that point a higher current will simply weld the contacts shut and the breaker cannot open. Resulting in a fire.

A simple crowbar short on a conventional car battery (Group24, 27, etc.) can throw higher amperage into the battery cables. Yes, for $100 or so you can buy a breaker rated for 5000A service, if you really want to.

But there's a reason that auto makers use FUSES at the battery. Fuses work, and they're much cheaper. They won't surprise you by welding shut and failing.

Now, if you just want to protect the wiring to a simple relatively small load device...breakers are fine. I've seen conventional 12v 40-50A breakers installed in the engine compartment, near the battery NOT near the exhaust manifold, fine after years of being there. FWIW.

The only BlueSeas terminal block fuses that I've seen are NOT designed for side-terminal or conventional top post batteries though. They are designed for marine batteries with vertical top posts, i.e. they are SAE/M8 or similar studs. Sometimes both pos and neg are the same size, sometimes not.

Are you guys saying they make a version for conventional car battery posts now?

 

[Project25_MASTR]

Your not paying much attention to what I said in my last post. Modern commercial radios don't go back to the battery post for their negative. They use the vehicle frame. The fact that NMO mounts are grounded at the sheet metal they are mounted on, is not the issue. The vehicle roof or fender is part of the vehicle frame. The radios are grounded to the same vehicle frame.



Can't control what the off shore radio companies do, but the US radio companies don't run a negative wire from the radio to the battery for good reason.



As SteveC0625 has pointed out, most of the new vehicles have done away with the braid and gone to a heavy wire from the battery negative post to the vehicle engine. This path carries the heavy starter motor current. There is no high current path from the vehicle frame to the engine other than this heavy wire path.



You need to understand how current flows in vehicles from the battery to the starter motor. The old wife's tale of the radio to coax to antenna mount needs to be put to bed. Back in the old days of positive grounds and floating ground circuit boards in radios, I may have given you an ear for part of the conversation, but it doesn't hold water today.

Note I never said anything about the starting current. I've actually seen instances where the negative fuse would be blown but the radio would still partially function.


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[Delivers1234]

A conventional circuit breaker "at" a battery, as the battery primary interrupt device, violates just about every electrical safety code or standard.



The reason being that conventional "12 volt" breakers are rated for about a 3000 amp current, and at that point a higher current will simply weld the contacts shut and the breaker cannot open. Resulting in a fire.



A simple crowbar short on a conventional car battery (Group24, 27, etc.) can throw higher amperage into the battery cables. Yes, for $100 or so you can buy a breaker rated for 5000A service, if you really want to.



But there's a reason that auto makers use FUSES at the battery. Fuses work, and they're much cheaper. They won't surprise you by welding shut and failing.



Now, if you just want to protect the wiring to a simple relatively small load device...breakers are fine. I've seen conventional 12v 40-50A breakers installed in the engine compartment, near the battery NOT near the exhaust manifold, fine after years of being there. FWIW.



The only BlueSeas terminal block fuses that I've seen are NOT designed for side-terminal or conventional top post batteries though. They are designed for marine batteries with vertical top posts, i.e. they are SAE/M8 or similar studs. Sometimes both pos and neg are the same size, sometimes not.



Are you guys saying they make a version for conventional car battery posts now?

I think it is made for either. It's the terminal fuse block. http://www.genuinedealz.com/blue-sea-systems-5191-fuse-block-for-battery-terminal-fuse

I just want to make sure it will fit the post.

 

[Project25_MASTR]

Easiest place I've found for GM is off the fuse block as it is common to GM pickups and SUVs.

The lug is where GM recommends to pull power for aftermarket brake controllers. Then just pop a hole in the grommet which the factory wiring harness enters the cab.

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[scottyhetzel]

Great info. Here guys....just remember to add a extra ground like 8 ga from the battery negative to the body. Generally all vehicles have a small grounds. The best way is to run the large ground to the motor block from the battery for great low resistance for the starter and for use by the alternator. Than run a large ground from the block to the frame. I like radio grounds short as possible. Less noise issues. Make sure all painted surfaces are shiny metal for eyelets. Use a nice copper bolt or bronze bolt and nut with lock washers.. than grease bolt for anti corrosion. Ground the hood and trunk with braided grounds...they are super flexible.