|
-
POSTING RULES

-
Donate yearly (please).
-
Advertise in here!
-
Today's Posts
|
Insert Pics
|

10-11-2020, 08:06 AM
|
|
|
|
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,218
|
|
Quote:
Originally Posted by Tankerpilot75
What’s the difference between a “ground strap” (mesh wire strap) and “ground cable.” Is one a better conductor than the other? My RV7A currently has a ground strap from the negative post to the firewall.
|
Do you have a cable (or strap) from the engine or starter back to the firewall? If not, the starter circuit is completing (grounding) back through a very inefficient and random path.
But to answer your question, a strap is supposedly a better grounding mechanism than a cable.
__________________
Kyle Boatright
Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
Last edited by Kyle Boatright : 10-11-2020 at 08:11 AM.
|

10-11-2020, 08:47 AM
|
 |
|
|
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 2,596
|
|
Starter ground
Cable or strap, makes no difference assuming they are both the same equivalent gauge.
I run the same gauge welding cable for both the starter and stater ground (note - starter ground - not under some greasy engine bolt). Take you pick, either #2 or #4. The ground goes from the big common firewall ground bolt to the starter ground.
Welding cable is very flexible and the insulation is amazingly durable. I did a torch test to compare welding cable insulation to Mil-Spec wire. The welding cable came out better.
Good quality US made welding cable is available on Amazon and many other places.
Carl
|

10-11-2020, 09:09 AM
|
|
|
|
Join Date: Jan 2015
Location: Oklahoma City, OK
Posts: 534
|
|
Quote:
Originally Posted by Kyle Boatright
Do you have a cable (or strap) from the engine or starter back to the firewall? If not, the starter circuit is completing (grounding) back through a very inefficient and random path.
But to answer your question, a strap is supposedly a better grounding mechanism than a cable.
|
My ground is from the battery (via strap) to the firewall. I will need to confirm this but I don’t believe there is a ground directly from the firewall to the engine. This could be the problem! I’ll check this out and let everyone know. I appreciate everyone’s input.
__________________
Jim Harris, ATP, T38, EC/KC-135A/E/R, 2008 RV7A, 2nd owner, N523RM (2015)
Superior XPIO-360, Hartzel CS prop, Aerotronics panel with Dual GRT Horizon WS, EIS, Garmin 340, 335 w/WAAS gps, Dual 430s (non-WAAS), TruTrak 385 A/P with auto-level, Electric trim, Tosten 6 button Military Grips, FlightBox wired to WS, Dynon D10A w/battery backup, 406 MHz ELT. Custom Interior, New TS Flightline hoses, Great POH!
Retired - Living the dream - going broke!
|

10-11-2020, 11:00 AM
|
 |
|
|
Join Date: Feb 2005
Location: LSGY
Posts: 3,198
|
|
Problem
Quote:
Originally Posted by Tankerpilot75
My ground is from the battery (via strap) to the firewall. I will need to confirm this but I don’t believe there is a ground directly from the firewall to the engine. This could be the problem! I’ll check this out and let everyone know. I appreciate everyone’s input.
|
It may not be "the" problem but it is definitely "a" problem to resolve.
Adding a good ground is not hard. I followed electric Bob's recommendation to have two ground straps from the engine to the FW/Battery.
http://www.rv8.ch/ground-point-on-firewall/
Some recommend the ground should come directly from the starter, which is also a very good idea. My grounds attach to the back of the engine, and with the EarthX battery, starting is very crisp.
|

10-11-2020, 11:11 AM
|
 |
|
|
Join Date: Oct 2005
Location: 08A
Posts: 9,500
|
|
Too often the ground cable from the engine to the airframe ground point is made of standard aircraft wire in some large gauge. Large gauge aircraft wire is waaaaaay too stiff, the result being loose crimps and broken terminals.
A certain popular kit manufacturer puts them in their firewall forward kits. If you have one, give it a flotation test at your first opportunity. If short span, replace it with a braided strap from B&C, Steinair, or similar. For longer spans do as Carl said and use finely stranded welding cable.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
|

10-11-2020, 11:34 AM
|
|
|
|
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,218
|
|
Quote:
Originally Posted by DanH
Too often the ground cable from the engine to the airframe ground point is made of standard aircraft wire in some large gauge. Large gauge aircraft wire is waaaaaay too stiff, the result being loose crimps and broken terminals.
|
In this respect, what is different between the ground strap and the starter's fat wire?
__________________
Kyle Boatright
Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
|

10-11-2020, 11:48 AM
|
|
|
|
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,297
|
|
Quote:
Originally Posted by Kyle Boatright
In this respect, what is different between the ground strap and the starter's fat wire?
|
the strap uses a large quantity of very thin wires. The battery cable (or thick gauge Tefzel) uses a small quantity of thick wires. The thinner the wire, the more it can flex without cracking or loosening inside of a crimp. Traditional battery cables requires support. A ground strap does not. Welding wire is very similar to a ground strap; Just braided vs. round and insulated.
Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
Last edited by lr172 : 10-11-2020 at 11:53 AM.
|

10-11-2020, 11:53 AM
|
|
|
|
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,218
|
|
Quote:
Originally Posted by lr172
the strap uses a large quantity of very thin wires. The battery cable uses a small quantity of thick wires. The thinner the wire, the more it can flex without cracking or loosening inside of a crimp. Traditional battery cables requires support. A ground strap does not. Welding wire is very similar to a ground strap; Just braided vs. round and insulated.
Larry
|
What I was getting at was why is a fat wire used as a ground strap more susceptible to problems than a fat wire used in the starter circuit?
__________________
Kyle Boatright
Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
|

10-11-2020, 02:14 PM
|
 |
|
|
Join Date: Aug 2009
Location: Southern California
Posts: 882
|
|
Quote:
Originally Posted by Kyle Boatright
What I was getting at was why is a fat wire used as a ground strap more susceptible to problems than a fat wire used in the starter circuit?
|
The starter wire is usually quite a bit longer than a ground strap meaning it has more room to flex as well as more opportunities to strain-relieve it. In my case, I have the starter wire secured to the engine mount to prevent strain at the firewall solenoid terminal and I have it secured to one of the sump bolts to prevent strain at the starter terminal.
Also, we have no choice but to use insulated round wire of some sort for the starter feed, but since the ground wire doesn't need to be insulated the strap is simpler and lighter...
Skylor
|

10-11-2020, 02:37 PM
|
|
|
|
Join Date: Jul 2018
Location: CA
Posts: 227
|
|
This discussion seems well grounded.
Ha!!!
__________________
20 dues paid member since 2018
RV6A
|
| Thread Tools |
Search this Thread |
|
|
|
| Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -6. The time now is 02:16 AM.
|