Battery fuses

[box23]

I have seen many times on this forum to fuse both the positive and ground wires at the battery for a mobile installation. I have read in other places, http://users.cot.net/~n6mrx/ares/mobile.htm being one example, that fusing the ground wire is a bad idea. That page says that if the ground fuse is open, the power could end up traveling by a different route, possibly dangerously.

I don't remember the exact reasoning for the pro ground fuse argument but it was something to do with a short in the ground wire causing the same alternate route.

Personally I think one fuse on the positive lead would suffice because if a short develops that fuse would blow resulting in an open circuit, shutting off any current. Additionally with the fuse near the battery, the greatest potential is located there, not hidden somewhere to create another short.

Any reasoning for the ground fuse?

 

[digitalanalog]

I work with batteries 8-12 hours a day, and i can tell you it makes no difference.

Fusing the Hot or the Not does the same thing.

as long as you have a fuse that is going to blow before the wire catches fire, your good.

Also, the location of the fuse (i.e. where it's at in the wire) can save or destroy a piece of electrical equipment.

 

[N_Jay]

You want to fuse the Positive (non grounded) connection as close to the battery as practical.

You are not only protecting the equipment, you are protecting THAT PIECE OF WIRE (and also the whole installation, car, etc.) should a short develop BEFORE the equipment.

On vehicles, you also fuse the ground IF it connects closer to the battery than the main vehicle ground. This is done to protect your equipment and the (relatively) thin ground conductor should the vehicles ground strap break. It prevents your ground wire from TRYING to carry the entire ground current of the vehicle (and often becoming a red hot fire starter).

Now, the rest of the "experts" here can tell you all the myths (err, I meant to say "facts") surrounding their particular favorite fusing method.

P.S. I could be nicer, but . . . Naaa:twisted::twisted::twisted:

 

[digitalanalog]

Most factory scanner dc power cords have the inline fuse already installed in the cord
and you will notice it's on the Positive lead, not the negative lead.

All equipment (scanners/cb's/ham/cd players/etc.)comes with a inline fuse in the Positive lead.

This is done for a reason, and has nothing to do with myths.

You could fuse Both (+) and (-), but it would be redundant.

 

[N_Jay]

Most factory scanner dc power cords have the inline fuse already installed in the cord
and you will notice it's on the Positive lead, not the negative lead.

All equipment (scanners/cb's/ham/cd players/etc.)comes with a inline fuse in the Positive lead.

This is done for a reason, and has nothing to do with myths.

You could fuse Both (+) and (-), but it would be redundant.

Most SCANNERS and CONSUMER equipment is NOT designed to be hooked directly to the battery.
Look at the LENGTH of the power cables and look at the type of insulation. Its not intended to be used under the hood.

Now go back and read my whole answer with both eyes open and at least 1/2 your brain turned on.

P.S. See, if I was nicer he would have read even less of my original post.:twisted::lol::twisted:

 

[digitalanalog]

all i can say is wow, try to help the op and this is what happens, wow

 

[N_Jay]

all i can say is wow, try to help the op and this is what happens, wow

Yes, I know.

Try to help them NOT be misinformed by providing the WHOLE answer, and look what happens.

P.S. Not sure what you do with batteries for 8 to 12 hours, but you could brush up on your knowledge of wiring safety.

 

[digitalanalog]

Yes, I know.

Try to help them NOT be misinformed by providing the WHOLE answer, and look what happens.

P.S. Not sure what you do with batteries for 8 to 12 hours, but you could brush up on your knowledge of wiring safety.

ROFLMAO
if you only knew..............ROFLMAO

Sorry OP.

 

[N_Jay]

ROFLMAO
if you only knew..............ROFLMAO

Sorry OP.

You might not be ROFLYAO if you read up on some of the emergency vehicle fires caused by overheated radio ground wires caused by bad vehicle ground straps and unfused radio ground leads.

 

[jim202]

The saga goes on and on with the story of why you need to fuse the negative wire in a mobile
installation.

Some facts that have shown up over the years.

1. Only the Jap Track radios are sold with the fuse included in the negative wire. This can
include Icom, Kenwood and other radios of this offshore type.

2. None of the US companies have ever used a fuse in the ground wire. This includes GE,
MA-COM, Motorola, RCA and others that are no longer with us.

3. The commercial radios have been installed into a large number of heavy duty type
vehicles like fire trucks, dump trucks, cement trucks, tractor trailer cabs and the like.

If there was a problem, don't you think there would have been a big flap in the two way
service group talks by now? I have been in the radio service field for well over 40 years
now and have never seen a fried radio. That doesn't mean that there hasn't been any
that other people have seen. However, I will say that there will be indications that there
may be a pending electrical problem in a vehicle long before the radio goes up in smoke
due to the ground wire with no fuse being blamed for the damage.

Think about it this way, in order for the ground wire of the radio causing the radio to be
smoked, the high starter current has to go through the ground wire. All the installations
that I have seen over the years has had a short ground wire from the radio to the vehicle
body. Explain to me how the full starter current can possibly go through this wire. It is
not between the negative post of the battery and the vehicle frame.

Sure there are those that just insist that the negative black wire of a commercial radio
needs to be run directly to the negative side of the battery post. Sure in this case you could
manage to get a high current to flow. However this is not the norm. The commercial radios
power cables do not come with a black wire as long as the red wire these days. As such, there
is no way you can even managed the direct battery connection on the negative side.

OK, I have said my little engineering piece. Let the flames pass over.

Jim

 

[N_Jay]

The saga goes on and on with the story of why you need to fuse the negative wire in a mobile installation.

Only by those not paying attention.

1. Only the Jap Track radios are sold with the fuse included in the negative wire. This can include Icom, Kenwood and other radios of this offshore type.

If you notice, these were often radios designed for either positive or negative ground operation, and often included power cables designed (and long enough) to go directly to the battery.

2. None of the US companies have ever used a fuse in the ground wire. This includes GE, MA-COM, Motorola, RCA and others that are no longer with us.

Again, if you were paying attention you would have noticed that the ground wire was shorter than the hot lead, and the instructions told you to ground the radio to the vehicle chassis.

3. The commercial radios have been installed into a large number of heavy duty type vehicles like fire trucks, dump trucks, cement trucks, tractor trailer cabs and the like.

Yes, Following the instructions that came with the radio.

If there was a problem, don't you think there would have been a big flap in the two way service group talks by now? I have been in the radio service field for well over 40 years now and have never seen a fried radio. That doesn't mean that there hasn't been any that other people have seen. However, I will say that there will be indications that there may be a pending electrical problem in a vehicle long before the radio goes up in smoke due to the ground wire with no fuse being blamed for the damage.

Well, maybe your shop has not kept up with the times..
Again (God, I wish people would READ), it is not about protecting the radio, it is about protecting the WIRE, and hence the vehicle.

Think about it this way, in order for the ground wire of the radio causing the radio to be smoked, the high starter current has to go through the ground wire. All the installations that I have seen over the years has had a short ground wire from the radio to the vehicle body. Explain to me how the full starter current can possibly go through this wire. It is not between the negative post of the battery and the vehicle frame.

Ding, Ding, Ding: We have a winner.

Sure there are those that just insist that the negative black wire of a commercial radio needs to be run directly to the negative side of the battery post. Sure in this case you could manage to get a high current to flow. However this is not the norm. The commercial radios power cables do not come with a black wire as long as the red wire these days. As such, there is no way you can even managed the direct battery connection on the negative side.

And the saga of NOT READING continues.

The fuse in the ground lead is EXACTLY for the case where the negative is ties in on the battery side of the main chassis ground.

There are only a few cases where this is done, but what it is done, the fuse is an IMPORTANT safety requirement.

OK, I have said my little engineering piece. Let the flames pass over.

Jim

A+ in Engineering, and a D- in reading.

 

[Thayne]

It surpises me to say it, but I gotta agree with N jay on this one.
Another thing that can happen is if there is a short not even caused by the installed radio and there is an unfused ground going directly to the battery when things get toasty (during the short) the unfused ground can make it worse when it is physically close to the toastiness.( Like taped or tie-wrapped to the harness)

Also I have found that some radios perform better with a ground right from the battery. It minimizes noise and possible voltage drop encountered when using a chassis return.(usually only a problem with transmitting with more than 20 watts like big motorola syntors, etc)

 

[N_Jay]

It surpises me to say it, but I gotta agree with N jay on this one.

Why the surprise?
:roll::roll::roll:

 

[Thayne]

Why the surprise?
:roll::roll::roll:

Not that it makes any difference to anybody, but you remind me of a boss I had back in the 80's & I felt he was overbearing & anal.

But all in all I enjoy your posts and am glad you are back--What a conundrum. . .

 

[jhweir]

If the neg battery cable corrodes (high resience) or comes loose at the body/eng connection point than the scanner/radio, if its ant is a body mount, coxal cable will provide a ground point throught the radio.

Also Motorla Spestra, Astro, Astro XTL ect. neg lead is about two feet longer than the positive lead.

When I install a radio, the positive lead goes directly to the positive post. On most cars the neg battery lead goes to the starter/eng block. But off the neg post there is a lead going from the battery post to the body. It is at this point, at the body, that I attache the radio neg lead.

 

[crazyboy]

Mark it in the books, I agree with N_Jay.

 

[richardc63]

The saga goes on and on with the story of why you need to fuse the negative wire in a mobile
installation.

Some facts that have shown up over the years.


2. None of the US companies have ever used a fuse in the ground wire. This includes GE,
MA-COM, Motorola, RCA and others that are no longer with us.



If there was a problem, don't you think there would have been a big flap in the two way
service group talks by now? I have been in the radio service field for well over 40 years
now and have never seen a fried radio. That doesn't mean that there hasn't been any
that other people have seen. However, I will say that there will be indications that there
may be a pending electrical problem in a vehicle long before the radio goes up in smoke
due to the ground wire with no fuse being blamed for the damage.

Think about it this way, in order for the ground wire of the radio causing the radio to be
smoked, the high starter current has to go through the ground wire. All the installations
that I have seen over the years has had a short ground wire from the radio to the vehicle
body. Explain to me how the full starter current can possibly go through this wire. It is
not between the negative post of the battery and the vehicle frame.

Sure there are those that just insist that the negative black wire of a commercial radio
needs to be run directly to the negative side of the battery post. Sure in this case you could
manage to get a high current to flow. However this is not the norm. The commercial radios
power cables do not come with a black wire as long as the red wire these days. As such, there
is no way you can even managed the direct battery connection on the negative side.

OK, I have said my little engineering piece. Let the flames pass over.

Jim

Sorry Jim, but your point 2 is incorrect. Every Motorola power cable I have seen supplied in the past decade (MCS2000 and XTL5000 in our case) have a blade fuse fitted in both the positive AND negative line.

Too often we allow debate to hide the good advice- Njay's advice reflects what I have seen accepted here in Australia as good practice. It IS normal practice here to take the negative to the battery. I would shoot any of my installers if they used the excuses you have for not doing so.

Regards,


Richard

 

[rico47635]

Sorry Jim, but your point 2 is incorrect. Every Motorola power cable I have seen supplied in the past decade (MCS2000 and XTL5000 in our case) have a blade fuse fitted in both the positive AND negative line.

Too often we allow debate to hide the good advice- Njay's advice reflects what I have seen accepted here in Australia as good practice. It IS normal practice here to take the negative to the battery. I would shoot any of my installers if they used the excuses you have for not doing so.

Regards,


Richard

Wow. Y'all don't mess around over there in Australia, huh?

 

[W6KRU]

+1 for N_Jay. The radio burning up would be a bummer but not nearly as bad as a red hot wire under the hood burning through the insulation of other wires.

 

[richardc63]

Wow. Y'all don't mess around over there in Australia, huh?

Well if you pay good money for an installer you expect him to be able to solder two lengths of black insulated wire & heatshrink them! "Sorry the cable was too short" doesn't cut it with me. Do it properly the first time... The Moto radios we get come with enough cable to run from the boot to the battery (black included) anyway so it is only an issue with recycled leads. And never ever use the chassis near the radio as an earth... aaargh!

But I did mean it figuratively speaking...

Cheers,

Richard