Engine to Batt ground - mechanical question

[rjcthree]

I have my engine grounded directly to the battery via a 2 gauge wire. The battery is an Oddessy on the firewall using Van's mount. The wire has crimped terminals at both ends, and is 12" long; it's pretty stiff. The connection is direct with no additional support, and goes straight back from the engine bolt to the battery, witha 2" rise.

What I'm concerned about is the mechanical loading of the battery terminals with the wire mass and engine motion/vibration. Will the battery survive?

In order to get a p-clip to the mount in there, I have to make a longer cable and tie to a different bolt. Not insurmountable, but adds mass, etc.

Anybody have any experience, or know of Oddessy failures due to terminal loading? Any other thoughts welcome....I'm two weeks from hauling the fueslage to the airport, and want to get this type of stuff squared away before....

Thanks, Rick

[JonJay]

The "standard" grounding method would be engine ground and battery ground to firewall. Battery ground is a multi strand strap.
I would not want to have the engine ground and associated vibration and movement tied directly to the battery terminal.

[brad walton]

I found some flat braided ground wire at Grainger. Flexible and works well. Others have used a section of welding lead and made their own flexible ground connection to the engine. I agree with what you are saying about the No. 2 wire from Van's being too stiff and putting mechanical loads on the battery terminal

[erich weaver]

Use this

http://www.bandc.biz/braidedbondingstrap.aspx

[rjcthree]

Ordered. Good plan. Rick

[Robert Anglin]

Originally Posted by JonJay

The "standard" grounding method would be engine ground and battery ground to firewall. Battery ground is a multi strand strap.
I would not want to have the engine ground and associated vibration and movement tied directly to the battery terminal.

I agree with this post. I have fixed a lot of cable problems down through the years and a good flex braded ground strap from the engine to the frame or engine mount will last a long time and give you little problems. You can still go down to the aircraft section of your local auto parts store and have them order you one, But, If you look in the B&C catalog you will find they supply them with any size ends you want on both ends and have a standard price for any length up to I think 15". You can have it cut to your required length and it is rated at number 2 wire sizing. Hope this helps. yours as always R.E.A. III #80888

[TCONROY]

I would highly suggest more than one engine to firewall ground. I can't begin to count how many folks thought they had engine sensor problems only to discover it was all due to poor grounding. I used two #2 AGW cables to ground my engine from each of the bolt holes near the lower engine mounts. Be sure to scrape away the paint on both sides of the hole on the engine to ensure the bolt and ring terminal are actually contacting metal.