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SyncroHead Samba Member
Joined: May 23, 2005 Posts: 1139 Location: Northern Nevada
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Posted: Fri Feb 05, 2021 11:23 am Post subject: Electrical Misconceptions?? |
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I'm partway through writing an e-book on the topic of basic vehicle electrical principles. I was inspired by someone once writing...
"The ground wire doesn't need to be a large size like the 12V wire, because it's 'just a grounding wire' ".
I'd like to make sure I cover other misconceptions in the book, so for those here that understand vehicle electrical systems...
What misconceptions have you heard?
Jim Davis _________________ "A Vanagon? It's not a car or a van. It's a hobby!"
Check out:
www.VANAVATION.com
www.SyncroSafari.org and
www.Vanagons.org
sphet wrote: |
I have *no* idea what the previous owner carried in his Westy... angry donkeys? |
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dhaavers Samba Member
Joined: March 19, 2010 Posts: 7733 Location: NE MN (tinyurl.com/dhaaverslocation)
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Posted: Fri Feb 05, 2021 11:32 am Post subject: Re: Electrical Misconceptions?? |
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Here's an easy 2 chapters: dielectric <vs> conductive grease...
- Dave _________________ 86 White Wolfsburg Westy Weekender
"The WonderVan"
<EDITED TO PROTECT INNOCENT PIXELS> |
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shagginwagon83 Samba Member
Joined: February 07, 2016 Posts: 3786 Location: VA/TN
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Posted: Fri Feb 05, 2021 11:43 am Post subject: Re: Electrical Misconceptions?? |
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When calculating wires size using this calculator, the 'length of wire' is the wire needed to complete the circuit.
so if you need to run both positive and negative to something 10ft away. You need to calculate it for 20ft.
https://www.wirebarn.com/Wire-Calculator-_ep_41.html _________________ Brandon
"Jo Ann" - '83.5 Westfalia EJ22e w/Peloquin
Instagram @joannthevan |
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DanHoug Samba Member
Joined: December 05, 2016 Posts: 4715 Location: Bemidji, MN
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Posted: Fri Feb 05, 2021 11:58 am Post subject: Re: Electrical Misconceptions?? |
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measuring voltage vs voltage drop
battery chemistry charging requirements
EMF from coil kickback
how to use a multi-meter
energy balance between interior heating with electricity vs fossil fuel
firing voltage requirements of spark plugs in free air, lean mixtures, heavy loads
Ohm's Law, period.
and... heh, heh.. crimping vs soldering connections _________________ -dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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dobryan Samba Member
Joined: March 24, 2006 Posts: 16473 Location: Brookeville, MD
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MarkWard Samba Member
Joined: February 09, 2005 Posts: 17007 Location: Retired South Florida
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Posted: Fri Feb 05, 2021 12:30 pm Post subject: Re: Electrical Misconceptions?? |
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Quote: |
Don't let the smoke out! |
It's hard to put it back. _________________ ☮️ |
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dabaron Samba Member
Joined: June 21, 2018 Posts: 2558 Location: Philly, mang
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Posted: Fri Feb 05, 2021 12:35 pm Post subject: Re: Electrical Misconceptions?? |
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the myth that direct current (DC) current flows from positive to negative. the lack of electrons in the "positive" pole attracts the surplus of electrons from the "negative" pole.
Ben Franklin had it backwards. _________________ 1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
BiWerks Design, LLC |
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DanHoug Samba Member
Joined: December 05, 2016 Posts: 4715 Location: Bemidji, MN
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Posted: Fri Feb 05, 2021 1:19 pm Post subject: Re: Electrical Misconceptions?? |
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dabaron wrote: |
the myth that direct current (DC) current flows from positive to negative. the lack of electrons in the "positive" pole attracts the surplus of electrons from the "negative" pole.
Ben Franklin had it backwards. |
this has just bothered me for ages. can't we call the + side the one with a surplus of electrons and the - side the one with a deficit? but then there's conventional current flow vs natural current flow. throw in some semiconductors and now there's holes to be filled.
great article on the controversy of current and electron flow:
https://www.nutsvolts.com/magazine/article/which-way-does-current-really-flow _________________ -dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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Howesight Samba Member
Joined: July 02, 2008 Posts: 3260 Location: Vancouver, B.C.
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Posted: Fri Feb 05, 2021 1:28 pm Post subject: Re: Electrical Misconceptions?? |
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Lead Acid battery basics and voltage.
Misconception:
"Van cranks real slow. Measured voltage and it's 12 volts, so can't be the battery."
*Sigh* _________________ '86 Syncro Westy SVX |
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dabaron Samba Member
Joined: June 21, 2018 Posts: 2558 Location: Philly, mang
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Posted: Fri Feb 05, 2021 1:49 pm Post subject: Re: Electrical Misconceptions?? |
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DanHoug wrote: |
throw in some semiconductors and now there's holes to be filled.
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the real fun starts with inductors and coils. my DC circuits class was a hoot. _________________ 1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
BiWerks Design, LLC |
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dabaron Samba Member
Joined: June 21, 2018 Posts: 2558 Location: Philly, mang
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Posted: Fri Feb 05, 2021 1:50 pm Post subject: Re: Electrical Misconceptions?? |
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Howesight wrote: |
LVan cranks real slow. Measured voltage and it's 12 volts, so can't be the battery."
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wait, my 12VDC car system operates at 13.4VDC... how does that make sense _________________ 1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
BiWerks Design, LLC |
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hans j Samba Member
Joined: May 06, 2006 Posts: 2713 Location: Salt Lake City UT
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Posted: Fri Feb 05, 2021 2:00 pm Post subject: Re: Electrical Misconceptions?? |
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Thinking that checking resistance with an Ohmmeter means it can carry correct current. _________________ 1986 Canadian Syncro Westy TDI - 1989 Syncro Single Cab - 2001 Audi S4 - 1981 VW Caddy ABA - 1980 VW Caddy EV - 1973 VW T-181 |
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valvecovergasket Samba Member
Joined: October 10, 2018 Posts: 1491 Location: pnw
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Posted: Fri Feb 05, 2021 2:03 pm Post subject: Re: Electrical Misconceptions?? |
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hans j wrote: |
Thinking that checking resistance with an Ohmmeter means it can carry correct current. |
its the first step past a visual inspection though!
maybe add something about wire insulation thickness not being a universal signifier of its current carrying capacity/not all insulation is the same haha _________________ MegaSquirt resource - SpitfireEFI.com
gone, but not forgotten: '83 tdi westy - swap thread |
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hans j Samba Member
Joined: May 06, 2006 Posts: 2713 Location: Salt Lake City UT
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Posted: Fri Feb 05, 2021 2:18 pm Post subject: Re: Electrical Misconceptions?? |
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It literally only tells you it's connected. The DVOM sends out such a tiny amount of voltage that it only needs one strand of wire to show continuity. It can't show if it's capable of carrying current.
If you are going to have the wire apart to check resistance, just load test it. _________________ 1986 Canadian Syncro Westy TDI - 1989 Syncro Single Cab - 2001 Audi S4 - 1981 VW Caddy ABA - 1980 VW Caddy EV - 1973 VW T-181 |
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valvecovergasket Samba Member
Joined: October 10, 2018 Posts: 1491 Location: pnw
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Posted: Fri Feb 05, 2021 2:20 pm Post subject: Re: Electrical Misconceptions?? |
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hans j wrote: |
If you are going to have the wire apart to check resistance |
except theres no need to take anything apart...
but i agree, load testing works well. ive been stumped by resistance check once recently and we found the drop with voltage. but id say more often than not, the resistance check points to problems pretty quickly beyond the "wiggle test" _________________ MegaSquirt resource - SpitfireEFI.com
gone, but not forgotten: '83 tdi westy - swap thread |
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gtinseth Samba Member
Joined: July 25, 2019 Posts: 76 Location: NW California
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Posted: Fri Feb 05, 2021 2:29 pm Post subject: Re: Electrical Misconceptions?? |
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Howesight wrote: |
Lead Acid battery basics and voltage.
Misconception:
"Van cranks real slow. Measured voltage and it's 12 volts, so can't be the battery."
*Sigh* |
This! Cover the nominal, 100% SOC, and 100% DOD for all the common battery chemistries. Also a section on the strengths and weakness of the different batteries (flooded, AGM, Gel, LiFePO4, etc). And an explanation of how to maximize discharge cycles for each type.
"How not to kill your house battery! You won't believe number 2!!!" |
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SyncroHead Samba Member
Joined: May 23, 2005 Posts: 1139 Location: Northern Nevada
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Posted: Fri Feb 05, 2021 2:46 pm Post subject: Re: Electrical Misconceptions?? |
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Thanks for the excellent feedback. There may be enough for a “Volume 2” book!
dabaron wrote: |
the myth that direct current (DC) current flows from positive to negative. the lack of electrons in the "positive" pole attracts the surplus of electrons from the "negative" pole.
Ben Franklin had it backwards. |
I may elect to just continue perpetuating this one in the interest of keeping the concepts simple. I don’t intend to describe molecular physics of electricity and won’t be using words like atoms, electrons, ions, etc. My hope is that readers will be able to troubleshoot a circuit, add a new circuit with properly sized wires, fuses, etc.
Please keep the suggestions coming.
Jim Davis _________________ "A Vanagon? It's not a car or a van. It's a hobby!"
Check out:
www.VANAVATION.com
www.SyncroSafari.org and
www.Vanagons.org
sphet wrote: |
I have *no* idea what the previous owner carried in his Westy... angry donkeys? |
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Ronzo_volvo_guy Samba Member
Joined: December 31, 2015 Posts: 194 Location: Connecticut
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Posted: Fri Feb 05, 2021 2:49 pm Post subject: Re: Electrical Misconceptions?? |
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Dave;
There NO SUCH THING as a "Conductive Grease" (a term invented by marketing departments!)...all grease is non-conductive/aka dielectric and will ENCAPSULATE a connection, but the place there zinc filled grease (which is also non-conductive shows its advantages is at the microscopic level, when the particles are compressed and in contact between two conductors (which happen to also have contaminants which want to corrode). Anti-Corrosive Zinc Paste will neutralize any corrosion, and so protects the connection long-term.
I have studied this for decades, and recommend it...see: https://www.sw-em.com/anti_corrosive_paste.htm
...including for making an encapsulated Gas-Tight-Joint when making crimps...see: https://www.sw-em.com/Wiring%20Notes.htm#Makin_a_Proper_Crimp
Cheers |
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VicVan Samba Member
Joined: July 01, 2015 Posts: 1826 Location: Vancouver Island, BC
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Posted: Fri Feb 05, 2021 3:03 pm Post subject: Re: Electrical Misconceptions?? |
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I lost the link, but a scientific study pointed out that many misconceptions in electricity among high school students were due to the comparison between water and electricity. The comparison just doesn't really work, and it confuses a lot of students. _________________ '90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH) |
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dhaavers Samba Member
Joined: March 19, 2010 Posts: 7733 Location: NE MN (tinyurl.com/dhaaverslocation)
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Posted: Fri Feb 05, 2021 3:34 pm Post subject: Re: Electrical Misconceptions?? |
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Ronzo_volvo_guy wrote: |
...There NO SUCH THING as a "Conductive Grease"... |
Yeah...I think we're on the same team here...
- Dave _________________ 86 White Wolfsburg Westy Weekender
"The WonderVan"
<EDITED TO PROTECT INNOCENT PIXELS> |
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