...and greatly increase the heat (think melted wire).... Going thinner by one gauge will increase the voltage drop in ....
Oh yes. If you let the magic smoke out then you'll need some of this -...and greatly increase the heat (think melted wire)...
Your source for current draw is wrong. Hitachi specs our starter at half a KW . So, 500W div by 12V gives us a little less than a 42A draw.I don’t like it because the braided jacket is a conductor, waiting to short out against something. Nice thing is it’s super flexible. Agree it could be an audio power supply cable. I can put a couple of layers of good quality loom if I decide to repurpose it.
I searched current draw for the starter and the spec is 75A @ 300 rpm engine speed. Looking at wiring specs, this call for some huge a$$ wire size.
Other posts here recommend 6 gauge and that’s what my Frankenwire looks like. I don’t have any 6 gauge in my stash but have a nice 8 gauge power cable (factory fused at 60A). If I use the 8 gauge am I headed for trouble?
I can buy 6 gauge welding cable (usually quite flexible) if that gauge is really necessary.
Opinions?
This is great info Jim, thanks! With this new to me intel, I think I’ll remove the wire I put back in and reinstall a new one since I have nice 8 gauge wire in stock.Your source for current draw is wrong. Hitachi specs our starter at half a KW . So, 500W div by 12V gives us a little less than a 42A draw.
View attachment 343296
Automotive (motorcycle) engineers tend to overbuild electrical systems. No idea why, but they do.
For determining wire size, I use the chart in AC-43.13. It's the aircraft mechanics 'bible'. Was written by the FAA based on what aircraft makers use. It's accurate, dead simple and what I used for over 40yrs.
I graphed out the starter needs below.
Purple on left denotes 12V.
Purple on right denotes 50A (to add a margin to the 42A we use).
Chase the 50A down (red line) until it stops. On the left we see it's valid for about 11ft of wire. Where those two lines intersect is our required wire size. When you're past one size, you automatically select the next bigger gauge.
That would be 10ga wire.... which is what my SG has run for the last 6-8 yrs with absolutely no problems.
View attachment 343297
Remember which thread? Gimmie a link and I'll point out the error in that thread.I found the 75A current draw in another thread in this group.
Oh yes. If you let the magic smoke out then you'll need some of this -
got one of those that's not all marked up?Your source for current draw is wrong. Hitachi specs our starter at half a KW . So, 500W div by 12V gives us a little less than a 42A draw.
View attachment 343296
Automotive (motorcycle) engineers tend to overbuild electrical systems. No idea why, but they do.
For determining wire size, I use the chart in AC-43.13. It's the aircraft mechanics 'bible'. Was written by the FAA based on what aircraft makers use. It's accurate, dead simple and what I used for over 40yrs.
I graphed out the starter needs below.
Purple on left denotes 12V.
Purple on right denotes 50A (to add a margin to the 42A we use).
Chase the 50A down (red line) until it stops at curve #3 (intermittent duty). On the left we see it's valid for about 5-6 ft of wire. Where those two lines intersect is our required wire size. When you're past one size, you automatically select the next bigger gauge.
That would be 10ga wire.... which is what my SG has run for the last 6-8 yrs with absolutely no problems.
View attachment 343297
I’d like a copy of that too! Laminate and stick to the lid of my tool boxes.got one of those that's not all marked up?
for reference and maybe shop wall use. ;^)
I was taught to go by the NEC they know a little something about electricity and conductors.Your source for current draw is wrong. Hitachi specs our starter at half a KW . So, 500W div by 12V gives us a little less than a 42A draw.
View attachment 343296
Automotive (motorcycle) engineers tend to overbuild electrical systems. No idea why, but they do.
For determining wire size, I use the chart in AC-43.13. It's the aircraft mechanics 'bible'. Was written by the FAA based on what aircraft makers use. It's accurate, dead simple and what I used for over 40yrs.
I graphed out the starter needs below.
Purple on left denotes 12V.
Purple on right denotes 50A (to add a margin to the 42A we use).
Chase the 50A down (red line) until it stops at curve #3 (intermittent duty). On the left we see it's valid for about 5-6 ft of wire. Where those two lines intersect is our required wire size. When you're past one size, you automatically select the next bigger gauge.
That would be 10ga wire.... which is what my SG has run for the last 6-8 yrs with absolutely no problems.
View attachment 343297
Keep in mind, Gary, this chart assumes you're using wire spec'd for aviation.... best quality in other words. If you use this chart, always round up to the next larger gauge to add a cushion.got one of those that's not all marked up?
for reference and maybe shop wall use. ;^)
One major factor left out in your chart is the length of the wire.... that's factored into the AC-43.13 chart. To stay below a 1 volt drop, we need to know the length. For instance, if you plot below the curve, all the way down to 2 ft of wire length, a 14ga wire would still keep you at or below the 1v drop. No one in their right mind would use 14ga to the starter solenoid, but at less than 2ft, you could.I was taught to go by the NEC they know a little something about electricity and conductors.
Based on what they say and what I learned in 45 years of working with automotive and industrial electricity I use 6ga works very well for me.
I'm not saying 10ga can't work but 6ga is better. Wire size is one thing where bigger is usually better.