Wire gauge for the leads on a Compufire reg\rect?

[JEEPRUSTY]

I am finishing up the wiring harness swap on my bike and I need to buy some new connectors.
I need a male spade on my + lead but all I have is crap small gauge ( or is that large? ) stuff.
Wire big connector hole small . The wire is almost an 1\8 of an inch in diameter.

Anyhoo I am at a loss. I have a lengthy piece of the wire that I cut off the unit to take into a store. Bad thing about that is all the connectors I have seen in automotive places are in sealed boxes.

 

[koolaid_kid]

Not sure what you have in Kanada. In the U.S. our wire gauges are 18 gauge, 16 gauge, etc. This is the diameter of the stranded wire itself, not the sheathing.
You Compufire has input and output wires. Which do you need?
The stator output to R/R input wires are 18 gauge on a Suzuki stator. There is nothing to be gained by going larger on these wires.
When I changed out my R/R, I put 16 gauge on the R/R ground wire, 18 gauge on the sense wire, and 14 gauge on the 12V output wire.

 

[JEEPRUSTY]

This is for the reg\rect output leads. The OEM wiring is all significantly smaller.

 

[posplayr]

I would run as much of the (+) 12 ga wire as you can till you meet up with the 16 ga Red disappearing into the harness.
I would cut down the (-) 12 ga and put a ring lug on it to your most convenient single point ground. proceed as normal from there.
For all other grounds 16 ga is sufficient as long as nothing is much over 1 ft per run.

 

[JEEPRUSTY]

So it is 12 gauge nice to know. I can go get some connectors.

I am using no more than 6 inches of the reg\rects = and _ leads.

The negative lead is going directly to the battery whereas the positive is going into the wiring harness. Its should be the same as the OEM layout.

 

[mikerophone]

So it is 12 gauge nice to know. I can go get some connectors.

Actually, it's 10 gauge.

 

[posplayr]

You are probably correct, it is thick stuff. A 10 ga it is clearly designed to allow the R/R to be mounted 4 ft from the battery. Otherwise there is no need for any wire above 14 ga (say 1 ft runs).

 

[Guest]

Use your wire strippers to remove some of the 10 gauge strands so it fits the connectors you get. The demand from the bike is going to be lower than the rated capacity of the Compu-fire so that's not a problem.

 

[JEEPRUSTY]

thanks guys for the help. Yah this wire is thicker than standard house wiring you find at a switch.

 

[koolaid_kid]

You are probably correct, it is thick stuff. A 10 ga it is clearly designed to allow the R/R to be mounted 4 ft from the battery. Otherwise there is no need for any wire above 14 ga (say 1 ft runs).

Why such large gauge? How much power are you transmitting? Have you checked the voltage drop over those runs? I am stunned at the figures you are quoting.
I checked a few simple calculators on the web for the voltage drop over length, and they seem to think differently. This is one simple calculator chosen at random: Calculator
I would just like to understand how you came up with those numbers.
Thanks.

 

[posplayr]

Why such large gauge? How much power are you transmitting? Have you checked the voltage drop over those runs? I am stunned at the figures you are quoting.
I checked a few simple calculators on the web for the voltage drop over length, and they seem to think differently. This is one simple calculator chosen at random: Calculator
I would just like to understand how you came up with those numbers.
Thanks.

This analysis was for the SSPB but will be real close for a standard fuse box. It focuses on the voltage drops between he battery and the R/r.

http://www.thegsresources.com/_foru...x-STANDARD-INSTALLATION&p=1965992#post1965992

 

[koolaid_kid]

Thanks. I don't quite follow the column V, which I take to be Voltage drop, and the %voltage drops column.
Taking only the 15 Amps examples, let's look at the first row under R/R extended to 4 ft with 10ga wire.
If you are charging at 14.5V you say there is a 0.060V drop, which equates to a 27.7% voltage drop?
I am sure I am missing something there.

 

[posplayr]

Thanks. I don't quite follow the column V, which I take to be Voltage drop, and the %voltage drops column.
Taking only the 15 Amps examples, let's look at the first row under R/R extended to 4 ft with 10ga wire.
If you are charging at 14.5V you say there is a 0.060V drop, which equates to a 27.7% voltage drop?
I am sure I am missing something there.

the analysis identified 4 wires which run between the r/r and battery. Because of the way current sits there are different currents in each of these legs. Each row uses the standard formulas to compute voltage drop base nog gs , length of wire and current. The individual voltage drops for each wire are in column v. But a four voltage drops are summed for each of the combination compared. The total voltage drop is also in column v but indicated in red. The first case is 1 ft length shows approximate 0.1 v drop so if the r/r is regulating at 14.5 there will be 14.4 at the battery due to these wirevoltage drops. Dirty connections can make it far worse . The percentages shown in green are just divining up the total voltage drop for each configuration to show how it is distributed amount the wire sets. It is not a percentage of the 14.5 supply although it could have been calculated that way. The intent was to show which wire was showing the biggest portion of the voltage drop.
note this is essentially an ideal configuration using a single point ground. If your system is different then you would have to make adjustments. For similar wire sizes and lengths the drops should always be worse.

 

[koolaid_kid]

Thanks. Each section shows the numbers for each of the 4 legs, with a sum of the voltage drops in red.
Clearly, being 1 foot away you could use 14 ga wire and obtain excellent results.
Since we cannot possible know the loss over the connections, we must assume perfectly clean connections at this time.
At 4 foot, the voltage loss using 10 gauge wire is still greater than the voltage loss at 1 foot using 14 ga wire.
However, at 4 foot using 14 gauge wire is only 0.329V, which is only 1.03% of the total 14.7V.
I normally look for less than 2% loss over the length of the wire, so would you disagree that 1.03% is acceptable? If so, please explain why.
Also, are you using 4 foot because the R/R would be located at the front of the bike, possibly for cooling?
Thanks.

 

[mikerophone]

...are you using 4 foot because the R/R would be located at the front of the bike, possibly for cooling?
Thanks.

A friend of mine has a newer model Triumph and it has the R/R right up front must run hot. The Compufire 55402 runs pretty cool as it is, but I had no room under my battery box or under either side panel for mine, and it comes with ~4 foot 10 gauge leads for all 5 wires so I mounted it to the frame up front above the oil cooler. I had a thread about it, but can't find it for some reason.

 

[posplayr]

Thanks. Each section shows the numbers for each of the 4 legs, with a sum of the voltage drops in red.
Clearly, being 1 foot away you could use 14 ga wire and obtain excellent results.
Since we cannot possible know the loss over the connections, we must assume perfectly clean connections at this time.
At 4 foot, the voltage loss using 10 gauge wire is still greater than the voltage loss at 1 foot using 14 ga wire.
However, at 4 foot using 14 gauge wire is only 0.329V, which is only 1.03% of the total 14.7V.
I normally look for less than 2% loss over the length of the wire, so would you disagree that 1.03% is acceptable? If so, please explain why.
Also, are you using 4 foot because the R/R would be located at the front of the bike, possibly for cooling?
Thanks.

I'm having a hard time deciphering what you are asking; I would have thought most of the below would have been clear from the original post. But I'll give it another go.

"Disagree that it is acceptable...? I'll hazard a guess that you are trying to figure out why your figure of 2% drops is a better answer than 0.1V or more specifically you want me to justify the 0.1V as being preferable to your 2% loss "rule of thumb".

A 2% drop of 14.5V is very nearly 0.3V. That means in a perfect situation (i,e. perfect connectors) and an R/R charging at 14.5V that your battery will never get over 14.2V. With the ga wires I provided the maximum is 14.4V. So in my mind 2% is too much and 0.1V is acceptable in view of what typical connector losses typically are. cThe revised Phase A voltage drops are either 0.2V or 0.25V (I forget) per side. I left them high so that people would not get frustrated trying to make them as small as possible (which I did). If it was 0.25 per side that would be a 0.5V total loss.

My hope is that as they work out cleaning the connections it would finally click click that the higher the drops the lower the charging voltage. At that point perhaps they are motivated to get rid of the voltages drops which are predominately connector losses. So even if teh conenctor losses are only 0.1V less than 1/2 of teh test thresholds and you use your 2% rule, the battery will never charge over 14.0V.

I'm using 4' because there are people that feel compelled to mount R/R's at the front of their bike. I can't possibly understand why people do that, it seem to be in some misguided notion that they will keep the R/R cooler by mounting up near the exhaust. I see microphone says he had no room in back.So the question becomes, how big should the wires be if there are 8 ft of wire drop v.s. 2 foot when only 1 foot away.

I know some of the people that purchased SSPB's for 1150's had to deal with the issue that the fusebox and the R/R are mounted away from each other (opposite sides of the bike) and there is a need for more than 1 ft lengths. That is what originally motivated the spreadsheet as I has already long selected 14 ga for the power leads and the main single point ground, while the tributaries feeding the SPG were 16g.

I think you should go back and reread the original post. It is pretty clear why that the analysis is based on calculating voltage drops so as to ensure proper battery charging. I don't think this has much if anything to do with where your 2% "rule of thumb". I would turn it around and ask you why you think a 2% "rule of thumb" applies but it would be rhetorical as I already know it does not.

 

[koolaid_kid]

O.K. Jim. As you wish.

 

[posplayr]

O.K. Jim. As you wish.

Actually wish I had not answered you at all.

I agonized over repeating what was already in the other post, especially since on face value it was very unclear what your question actually was.

Although I had a pretty clear idea about where you were driving; I did not want to jump to any conclusions.

 

[JEEPRUSTY]

Well good golly got here all connected. Was shocked that a local shop had 10-12 gauge connectors.

Now another problem occurs I get a stumble like the bike is running out of gas or not running on all 4 cylinders. This has gotten worse since it started.

What miraculous fault could account for this? Since it happened right after affixing a healthy clean wiring harness it leads me to believe it must be lectrical in nature. But my battery is charging and when I get the degradation in performance I can blow the horns with aplomb yet I see the fuel gauge rising and falling.

Woe is me a new Ducati for me? Nay I must fix this wretched beast.

Feel free to laugh.

 

[posplayr]

If you pass the quick test, make sure you have full voltage to the coils.