Fuse question

[bduffey]

My recently installed accessory harness/socket was popping the 1 amp fuse. I've learned not to plug in anything stronger than a cell phone or GPS. My question is.... my dealer removed the 1 amp and installed a 10 amp in its place. Any possible issues I should be aware of?

 

[ste7ios]

Do you mean Honda's sub-harness that came with a fuse and a relay? Is it a custom made?

 

[bamamate]

If this is the Honda acc outlet, the whole harness is on a 7.5amp fuse in the fuse box so that would blow before the 10 amp. Increasing the fuse size above the rating for the wire and socket is not a good idea. The fuse is there to blow, and stop the electrical flow, before damage and possibly fire occurs in the circuit being protected. Since Honda provided a 1amp fuse, that is all the socket and wiring is officially rated for.

 

[Spaceteach]

The entire accessory harness circuit has a fuse that should be rated at 7.5 amps. It's located on the fuse panel beside the battery close to the relay that supplies switched power to the harness. Since the harness is designed to supply power to more than one accessory, I'm guessing they use lower rated fuses in each accessory power line as in one amp for the accessory socket, x amp fuse for heated grips, x amp fuse for accessory lights, etc, with the 7.5 amp fuse to limit the total amperage going to all the accessories. At any rate, as long as your harness is the Honda accessory and it was installed with the Honda relay kit, the main 7.5 amp fuse will blow if something causes a short in any of the accessory harness circuits. Putting a 10 amp fuse on the line going to the accessory socket is really the same as not having a separate fuse since the main fuse will blow if the current draw goes above its rating.

It's been a while since I installed the accessory sub harness and now that I think about it, I'm not sure if the relay kit fuse is 5 or 7.5 amps, but either way it will blow before the 10 amp fuse in your accessory socket lead.

OOPS - Bamamate beat me to it. What he said.
Bob

 

[SergeantChuck]

This is definitely not my area of expertise but making a jump from 1 amp to 10 amps seems a bit extreme. I've mentioned before that I work on Caterpillar equipment. Specifically the cab. It has two fuse boxes with about 100 fuses. We are prohibited from placing a larger fuse than what is called out on the print. Period. If we are having multiple failures we sometimes step up to a fuse that is 5 amps larger just as a test while troubleshooting but we are not allowed to leave it in place.

If a circuit was going to require at 30amp fuse you will most likely have 10 gauge wire. Something only needing a 1amp fuse COULD have 18 gauge wire. It’s just like overloading a cheap surge protector with items that draw a lot of power. The cord will get hot and possibly melt. The same thing can happen if your using took large of fuse on the wrong gauge wire. Basically you might be asking for a thermal event.


Again, I’m no electrical engineer and I have not looked at the wiring enough to know what gauge wires we are talking about. I just think going from a 1amp fuse to a 10amp fuse is quite a jump. If it was the 7.5amp fuse he removed and replaced it with a 10amp that is another story but still not a good idea to exceed the manufacturers recommended fuse size.

 

[Josh H]

Most USB chargers use at least 2.1 amps to charge your phone and the dual USB chargers can use up to 5 amps with two devices charging at the same time. I use a 5 amp fuse in mine. The socket and wiring will be fine with a 5 amp fuse, however a 10 amp fuse is a little excessive. Replace the 10 amp fuse immediately with 5 amp or less.

 

[silverhound]

Most USB chargers use at least 2.1 amps to charge your phone and the dual USB chargers can use up to 5 amps with two devices charging at the same time. I use a 5 amp fuse in mine. The socket and wiring will be fine with a 5 amp fuse, however a 10 amp fuse is a little excessive. Replace the 10 amp fuse immediately with 5 amp or less.

^^^^What he said. Plus I agree that with a 10amp fuse in the circuit you might as well not have one at all. BTW...your dealer is a dumbass.

 

[Josh H]

BTW...your dealer is a dumbass.

+1! I didn't want to say it. But I'm glad you did!!

 

[ste7ios]

I checked the instruction manual: there are two fuses, a 1 A and a 7.5 A in the relay. The replacement of the 1 A with a 10 A fuse is totally wrong. No comments for your dealer!

 

[bduffey]

So then to be clear.... The 10 amp is excessive, but since the box fuse is 7.5, there's no real danger as that fuse will go before the 10 amp can do anything, correct? At least that way if a fuse goes, I don't have to remove the cowling to get at the 10 amp. Or am I off on that?

Obviously electronics and wiring is not my thing!

 

[ste7ios]

I don't know how it works - I've to check the electric diagram - but you must put back the 1 A fuse. The 7.5 A is another fuse inside the relay, not in the box. Don't confuse them!

 

[silverhound]

So then to be clear.... The 10 amp is excessive, but since the box fuse is 7.5, there's no real danger as that fuse will go before the 10 amp can do anything, correct? At least that way if a fuse goes, I don't have to remove the cowling to get at the 10 amp. Or am I off on that?

Obviously electronics and wiring is not my thing!

Yes, your assessment is correct in principle subject to how you want to interpret "real danger".

Probably nothing will happen as long as you keep whatever you plug into the accessory plug a low draw device i.e. phone charger, GPS, etc. Something like a mini air compressor could possibly overheat the wires of that circuit but if a short or over-draw occured the 7.5amp fuse at the relay should blow first.

 

[treybrad]

So then to be clear.... The 10 amp is excessive, but since the box fuse is 7.5, there's no real danger as that fuse will go before the 10 amp can do anything, correct? At least that way if a fuse goes, I don't have to remove the cowling to get at the 10 amp. Or am I off on that?

If you got a short in the wiring after the 7.5A fuse, but before the 10A, the 7.5A wouldn't blow and you'd be at the mercy of the 10A. Now... is 7.5A vs. 10A going to result in your motorcycle burning to the ground... ? Probably not, but it's certainly incorrect, and I'm surprised a dealer would do that. I don't have the OEM relay stuff, so I'm not sure what gauge wire you're dealing with, that's another consideration though.

trey

 

[Alabama Al]

If the fuse is to big, the wire becomes the fuse. NOT GOOD

 

[Spaceteach]

If you got a short in the wiring after the 7.5A fuse, but before the 10A, the 7.5A wouldn't blow and you'd be at the mercy of the 10A. Now... is 7.5A vs. 10A going to result in your motorcycle burning to the ground... ? Probably not, but it's certainly incorrect, and I'm surprised a dealer would do that. I don't have the OEM relay stuff, so I'm not sure what gauge wire you're dealing with, that's another consideration though.

trey

There is one flaw in your description. When the 7.5 amp fuse blows, how are you getting power to the 10A ?

The battery is connected to the fuse and relay panel with relatively heavy guage wire. The 7.5 amp fuse is located right by the power relay. The 1 amp (or 10 amp in this case) is located in the wiring between the accessory sub harness and accessory socket. Basically, power goes from battery to relay/7.5 amp fuse through stock wiring harness then through sub-harness then through 1 (or 10) amp fuse to accessory socket. In other words, any current flowing through the accessory fuse has to go through the panel fuse first. You can't blow the 10 amp because the 7.5 amp will blow first.

That's my story and I' sticking with it
Bob

 

[silverhound]

There is one flaw in your description. When the 7.5 amp fuse blows, how are you getting power to the 10A ?

The battery is connected to the fuse and relay panel with relatively heavy guage wire. The 7.5 amp fuse is located right by the power relay. The 1 amp (or 10 amp in this case) is located in the wiring between the accessory sub harness and accessory socket. Basically, power goes from battery to relay/7.5 amp fuse through stock wiring harness then through sub-harness then through 1 (or 10) amp fuse to accessory socket. In other words, any current flowing through the accessory fuse has to go through the panel fuse first. You can't blow the 10 amp because the 7.5 amp will blow first.

That's my story and I' sticking with it
Bob

I concur. I do not see how you could get a short in the circuit as described in Treybrad's post where the 10amp fuse would blow before or instead of the 7.5amp regardless of where the short occurred, whether before or after the 10amp fuse.

 

[treybrad]

There is one flaw in your description. When the 7.5 amp fuse blows, how are you getting power to the 10A ?

D'oh, busted. You're absolutely right, not sure how I convinced myself otherwise....

trey

 

[bduffey]

So would an option for me be to have the assembly rewired so that it ran straight of the battery (or through a battery tender) and then replace the fuse with a 1 amp? Would that do it? And wouldn't that result in the socket always powered up, even when the ignition is off?

 

[670cc]

So would an option for me be to have the assembly rewired so that it ran straight of the battery (or through a battery tender) and then replace the fuse with a 1 amp? Would that do it? And wouldn't that result in the socket always powered up, even when the ignition is off?

One thing to consider is the current rating of the socket itself. It could be 5 amps, it could be 15 amps. If not labeled, it would be hard to know.

The second thing is, what would you like to plug in there? If you just need 2 or 3 amps for a pair of USB devices, then just replace the 1 amp fuse with a 5 amp and it should be a safe setup. If you're thinking of plugging in an air compressor, well then the Honda accessory harness is not going to get it done. If you want to supply a high current device, an option would be to leave the switched Honda socket there fused at 5 amps, then add an unswitched second socket in the frunk, or use an SAE connector ("battery tender connector") to drive high current devices. Wire this second socket direct to the battery, with appropriate sized wire, and with an in-line fuse holder fused at 15 amps.

 

[ste7ios]

I checked the instruction manual: there are two fuses, a 1 A and a 7.5 A in the relay. The replacement of the 1 A with a 10 A fuse is totally wrong. No comments for your dealer!

Well, I misread the instruction manual. There is only one fuse for the relay set, a 7.5 A. It's not in the relay but in the box (position 1, just above the relay). The 1 A fuse referred for the 12 V socket and it's located in socket's harness.

So the total capacity of the switched power cabling of subharness is 7.5 A and the socket can only cope with a max of 1 A (12 Watt).