Hi all need some advice when connecting cb direct to car battery so far have wire with inline fuse connected to positive on battery negative connected to chassis of vehicle .... One question do I need to put an inline fuse in the negative cable connected to chassis read mixed reports .. helpppppppppp
Tony Bev said
06:50 PM Dec 9, 2016
A few years ago, I put a hard wired Uniden UHF in my car
The pamphlet said to wire it directly to the battery, with a fuse on the positive terminal of the battery
It did not mention a fuse on the negative terminal, and I did not put a fuse on the negative side of the circuit
Hope that this info is helpful to you
Dougwe said
07:15 PM Dec 9, 2016
I have done quite a bit of 12v, only, wireing and only ever put a in-line fuse on the possitive wire.
Keep Safe on the roads and out there.
macka17 said
07:29 PM Dec 9, 2016
All Sparkies information will tell you
Positive side for fused/breakers etc.
Basically that side stops the flow of energy from battery at fuse point.
If On Neg side the current can keep flowing along the Pos wire
to anywhere there's an earth\short...
If there is one.
goldenyears said
09:16 PM Dec 9, 2016
thankyou tony appreciate the info ...
dishlicker said
08:47 AM Dec 10, 2016
Hi there golden yrs yes you only need a fuse on the active (red) wire but if you have it direct to battery then you need to turn it of each time you stop or you may flatten the battery.
valiant81 said
09:56 AM Dec 10, 2016
Hi all;
Me being a amateur radio operator ( VK3SVG ) with a full licence . All of our radio equipment that is used on 12 Volt, there are fuses in both the positive and negative DC lines AND to connect both DC lines to your battery. Reason being that a lot of radios will draw +20 Amps on transmit. So with my understanding if the radio has two fuses in the DC power cables, the manufacture would have a reason to as why. My guess would be to allow the transceiver to pull max current @ full power and not rely on a poor earth that could reduce the amount of RF power that the transceiver would be capable of transmitting. Also the reduced voltage could destabilise the transmitter.
On another note, in a past life i used to install car audio, small and big systems. One job that i was asked to have a look at had 3 x power amplifiers and auxiliary batteries in the boot, sub speakers etc. Had to trace a problem of intermittent noise that was hard to trace. Ended up the previous installer had used the car's chassis as a earth for the whole system. It was only when i replace the main power feed cable with new cable from the main battery to the DC to DC converter in the boot to keep the batteries in the boot fully charged. This cable had both the Positive and Negative cables in the sheath.
erad said
10:06 AM Dec 10, 2016
A fuse is inserted into a circuit on the 12V side to protect the wiring should a short circuit or overload occur. You don't want the wiring to catch fire. Putting a fuse on the earth side of the circuit is useless because by the time the current gets to this point, the voltage is effectively zero at this point. Putting a fuse in the circuit is more likely to give troubles later on as it is another point of failure.
goldenyears said
10:09 AM Dec 10, 2016
explained very well valiant thankyou .... now I'm even more confused lol
Aus-Kiwi said
01:19 PM Dec 10, 2016
If it blows on earth side ? Just means the appliance is still a live . Not a big issue on LV DC . . Btw a sheathed wire souls only be earthed at one end . Or it becomes a conduit and prompts RFI . How they wire EFI ECU's .
T1 Terry said
02:15 PM Dec 10, 2016
As far as I know the fuse in the negative lead is for lightening strike protection. Not necessarily to protect the equipment but to protect against the thing catching fire or exploding. An RV is unlikely to suffer lightening strikes, boats are a different matter, but the manufacturer is covering their butt by saying it should be fused on both power cables. I would think the amateur radio would have a rather large antenna and this could become a lightening rod in some circumstances, so another case supporting the lightening strike protection
T1 Terry
Aus-Kiwi said
04:00 PM Dec 10, 2016
If it blows on earth side ? Just means the appliance is still a live . Not a big issue on LV DC . . Btw a sheathed wire souls only be earthed at one end . Or it becomes a conduit and prompts RFI . How they wire EFI ECU's .
Ron-D said
07:18 PM Dec 10, 2016
I can't see any need to connect a fuse to both wires, I have always connected to the positive side near the battery and have blown a few over the years ,and once the positive side has been isolated by the blown fuse there's nothing there at all in the circuit to cause problems as far as I can tell...
Vince said
10:47 AM Dec 11, 2016
valiant81 wrote:
Hi all;
Me being a amateur radio operator ( VK3SVG ) with a full licence . All of our radio equipment that is used on 12 Volt, there are fuses in both the positive and negative DC lines AND to connect both DC lines to your battery. Reason being that a lot of radios will draw +20 Amps on transmit. So with my understanding if the radio has two fuses in the DC power cables, the manufacture would have a reason to as why. My guess would be to allow the transceiver to pull max current @ full power and not rely on a poor earth that could reduce the amount of RF power that the transceiver would be capable of transmitting. Also the reduced voltage could destabilise the transmitter.
This is exactly what I have done too (vk2fbuz) and all other installed extras have been wired direct to the batteries with no body or chassis earthing.
Cheers
Vince
Aus-Kiwi said
10:59 AM Dec 11, 2016
If you have a lightning strike ? I highly doubt a 20mm to 50mm wide fuse with prevent damage .. These suckers come from the clouds .. Lol
T1 Terry said
11:56 AM Dec 11, 2016
Aus-Kiwi wrote:
If you have a lightning strike ? I highly doubt a 20mm to 50mm wide fuse with prevent damage .. These suckers come from the clouds .. Lol
Electrickery will always find the easiest path and there is sure to be an easier path than a 50mm arc gap. Remember the lightening strike goes from the ground to the clouds, not the other way around
Hi all need some advice when connecting cb direct to car battery so far have wire with inline fuse connected to positive on battery negative connected to chassis of vehicle .... One question do I need to put an inline fuse in the negative cable connected to chassis read mixed reports .. helpppppppppp
A few years ago, I put a hard wired Uniden UHF in my car
The pamphlet said to wire it directly to the battery, with a fuse on the positive terminal of the battery
It did not mention a fuse on the negative terminal, and I did not put a fuse on the negative side of the circuit
Hope that this info is helpful to you
Keep Safe on the roads and out there.
Positive side for fused/breakers etc.
Basically that side stops the flow of energy from battery at fuse point.
If On Neg side the current can keep flowing along the Pos wire
to anywhere there's an earth\short...
If there is one.
thankyou tony appreciate the info ...
Hi there golden yrs yes you only need a fuse on the active (red) wire but if you have it direct to battery then you need to turn it of each time you stop or you may flatten the battery.
Hi all;
Me being a amateur radio operator ( VK3SVG ) with a full licence . All of our radio equipment that is used on 12 Volt, there are fuses in both the positive and negative DC lines AND to connect both DC lines to your battery. Reason being that a lot of radios will draw +20 Amps on transmit. So with my understanding if the radio has two fuses in the DC power cables, the manufacture would have a reason to as why. My guess would be to allow the transceiver to pull max current @ full power and not rely on a poor earth that could reduce the amount of RF power that the transceiver would be capable of transmitting. Also the reduced voltage could destabilise the transmitter.
On another note, in a past life i used to install car audio, small and big systems. One job that i was asked to have a look at had 3 x power amplifiers and auxiliary batteries in the boot, sub speakers etc. Had to trace a problem of intermittent noise that was hard to trace. Ended up the previous installer had used the car's chassis as a earth for the whole system. It was only when i replace the main power feed cable with new cable from the main battery to the DC to DC converter in the boot to keep the batteries in the boot fully charged. This cable had both the Positive and Negative cables in the sheath.
A fuse is inserted into a circuit on the 12V side to protect the wiring should a short circuit or overload occur. You don't want the wiring to catch fire. Putting a fuse on the earth side of the circuit is useless because by the time the current gets to this point, the voltage is effectively zero at this point. Putting a fuse in the circuit is more likely to give troubles later on as it is another point of failure.
explained very well valiant thankyou .... now I'm even more confused lol
T1 Terry
I can't see any need to connect a fuse to both wires, I have always connected to the positive side near the battery and have blown a few over the years ,and once the positive side has been isolated by the blown fuse there's nothing there at all in the circuit to cause problems as far as I can tell...
This is exactly what I have done too (vk2fbuz) and all other installed extras have been wired direct to the batteries with no body or chassis earthing.
Cheers
Vince
Electrickery will always find the easiest path and there is sure to be an easier path than a 50mm arc gap. Remember the lightening strike goes from the ground to the clouds, not the other way around
T1 Terry