I know some builders run a dedicated ground to the starter.
Is the case grounded?
Which bolt did you use?
Is this one avaiable?
View attachment 10962
I ground the engine on the starter ground lug on all three RVs, using the same #2 or #4 welding wire that provides power to the starter.
The starter is what takes the current, why not provide it with the best ground? The amount of metal to metal contact between the starter and the engine case is huge so no issue with the engine itself being grounded. And as pointed out for our RVs there is typically a strap between the alternator and the starter - so a byproduct is a solid ground for the alternator.
I note with interest the continued use of fraying ground straps under greasy engine bolts. There are better options.
Carl
Thanks Carl. That's what I would like to install. #2 battery to starter.
Which is ground? One is labeled for power so that one is obvious.
Where on the starter did you tie the ground?
I also plan a ground to the engine case.
View attachment 10964
I ground the engine on the starter ground lug on all three RVs, using the same #2 or #4 welding wire that provides power to the starter.
The starter is what takes the current, why not provide it with the best ground? The amount of metal to metal contact between the starter and the engine case is huge so no issue with the engine itself being grounded. And as pointed out for our RVs there is typically a strap between the alternator and the starter - so a byproduct is a solid ground for the alternator.
I note with interest the continued use of fraying ground straps under greasy engine bolts. There are better options.
Carl
Indeed - this is working fine for me. The part of the engine that the starter bolts to is very clean, flat, un-anodized metal, securely bolted, so is probably conducting pretty good to the engine case.Why add the weight? The engine case is more than capable of carrying the return ~300A to a ground point.
Why add the weight? The engine case is more than capable of carrying the return ~300A to a ground point.
The starter case is the ground...and that is a picture of the starter solenoid, not the starter motor.
Yes. I know. Carl mentioned a ground lug. I've swapped a lot of starters on autos and it got me wondering if somehow airplane starter was different.
Still waiting for.an answer to my question on where he grounded the starter.
My starter is grounded to the engine case.
While on the topic of engine grounding....
Here’s what mine looks like. The airframe ground is attached to the engine mount. Is this acceptable?
View attachment 10981
I would not recommend attaching the ground like that. The bolts, nuts and washers all have standards to which they made, including compression strength. Unless you have a report that says the copper end lug on that cable is just as strong in compression as the steel washer and bolt, I would avoid using it as a structural fastener. I think over time, the copper will crush and you'll lose preload on that bolt.
I would not recommend attaching the ground like that. The bolts, nuts and washers all have standards to which they made, including compression strength. Unless you have a report that says the copper end lug on that cable is just as strong in compression as the steel washer and bolt, I would avoid using it as a structural fastener. I think over time, the copper will crush and you'll lose preload on that bolt.
Thanks everyone for the info. The pictured and drawings help a lot. I will switch to a case ground.
As long we are, sort of, on the subject.
The plans call for two copper bars between the contactors.
The stuff I got from AS is .138" thick. It barely fits the output of the Master. No way two will fit.
What did you use?
Next question
The contactors studs are not steel.
What is the torque spec for the contactor nuts?
Thanks for the feedback. I’ll look at remediating this.
Traditional ground straps often have steel terminals instead of copper to allow this type of connection.
P20 buss bar detail from the OP-12 DWG, see attached. Made from .063"
I went by "feel & sight" for the torque -- use two wrenches, one to hold the stud and keep from turning, tighten the nut down while observing the lock washer, tighten nut until lock washer is flat.
I'll look around for the mfg. recommended values (White/Rogers was the mfg. IIRC)
*edit - W/R Data sheet suggests 44 to 55 in.lb. for Contact Terminal Stud nut torque.*
B
Thanks
I suppose the question still stands.
Will one bar .138" suffice or is there some electronic reason for two .063" bars?
If Vans wanted a certain bar, I wish they would have included it in my FWF kit!
Thanks
I suppose the question still stands.
Will one bar .138" suffice or is there some electronic reason for two .063" bars?
If Vans wanted a certain bar, I wish they would have included it in my FWF kit!
Hey Larry, I'm working on the wiring now if you want to check mine. On the master and the starter Relay/solenoids you need the OP-30 for the Tri gear which shows a ES WH-P4F 2 AWG cable to connect both master and starter relays instead of the copper bars.
Hey Brian, looked at OP-31 note 2 was :
2. Both Tail Dragger and Tricycle gear battery battery configurations shown.
So If I am missing something which is common, To me that just shows the wiring from engine Battery to panel switches that will be deferent from where the battery is mounted.
Larry has an RV7A so I just assumed his Battery, Master and Stater Relay/ Solenoid should be in the Tricycle A Detail instead of the Detail B for RV7 tail dragger which I have. Cheers Bob
Some of us used copper pipe from Home Depot, flattened it, and fashioned our own bars...
All other things being equal -- you should be fine with a .138" bar...
*edit -- the math ---*
The reason? They (Van's) are trying to create an equivalent conductor as 2ga wire; 2ga wire has a diameter of ~.258", thus a cross sectioned area of ~.052in.sq. A single piece of copper 1/2" wide and .063" thick has a cross section of .0315in.sq., doubling that yields .063in.sq --- just a hair more than 2ga wire.
Wall thickness for 1" copper tubing is between .035" and .065"
Most all Lyc engine cases have a hole in the case web that is directly aft of the base of the dip stick tube. This hole is used for no purpose on an RV so it makes it a great ground cable attach point (just be sure to fully remove an paint / primer down to bare metal for a good electrical bond).
Is this the spot you were referring too?
I'm not sure why the pics attached sideways.
View attachment 11403
View attachment 11404
Is this the spot you were referring too?
I'm not sure why the pics attached sideways.
View attachment 11403
View attachment 11404
Yup, that's one of them...
Ok, now that We’ve established A good place to ground the engine case, what about the firewall ground? I don’t have a dedicated ground bar on the firewall. Mine is grounded on the engine mount, which was decided to be less than ideal.
What about using the rudder pedal anchor point?
View attachment 11415
See green circle...Can you drill out this rivet and put an AN4 or AN5 bolt in there?
If the battery(s) are not grounded on the firewall, then I assume you have a rear mounted battery and are using a nearby airframe ground. Is this correct?
It’s a flying airplane, so it would be a pain, but possible.
See Carl's comment -- (not about belt/suspenders); where's the (-) terminal on your battery connected?
That might already be ok if the battery tray is well-grounded to the airframe. When I had my tray in the back it had several square inches of contact with the airframe, with I believe 3 10-32 countersunk screws holding it down.It’s a rear mounted battery, and the battery negative is attached to the frame of the battery tray. I don’t have a picture. I intend to correct this, and ground it on one of the airframe angles. I finally got the correct hardware together.