Importance of Wire Support

[RV7A Flyer]

Originally Posted by Stevea

OK, so do not "beat a crimp (tool) with a hammer". Instead, put it in a vice and crank it down in a controlled manner, to the required crimp height. Worked for me on all the large crimps, with tefzel wire. None of them have misbehaved in 1000+ hrs.

The other important part of this, whatever wire is used, is to properly support the wire all the way out as close as possible to the termination point. This is not a place to scrimp on mounting hardware (ie: do not use zip ties to attach to some engine/engine mount hard point). Use Adel clamps to a rigid part of the engine, engine mount, etc. Yes, they can be a PITA to install (although there are several well documented methods to make installation easier). If the fat wires (or any wire, really) can not move, they can not fatigue, and can not break. And if ya don't want the wire to move, SECURE IT to a hard point.

Take a look under the hood of any modern car. Wire bundles are secured to something. Nothing is put in place, just hoping it will stay there.

Here are photos of my wire runs to the alternator and the starter:
Attachment 27485

Attachment 27486

Attachment 27487

Attachment 27488

These are lovely wire runs and supports and all, BUT...the problem here is not, I think, with the wire run. It's with the *bend* in the wire to take it to the terminal post. The large, stiff wire wants to unbend into a straight run, thus putting stress on the crimped connecter, ultimately leading to a break (or some number of strands break, which then leads to heating in the remaining ones, etc.). At least, that's my guess, based on what I've seen on friends' RVs with the same wires and runs.

[Stevea]

Originally Posted by RV7A Flyer

These are lovely wire runs and supports and all, BUT...the problem here is not, I think, with the wire run. It's with the *bend* in the wire to take it to the terminal post. The large, stiff wire wants to unbend into a straight run, thus putting stress on the crimped connecter, ultimately leading to a break (or some number of strands break, which then leads to heating in the remaining ones, etc.). At least, that's my guess, based on what I've seen on friends' RVs with the same wires and runs.

OK. Probably should have mentioned this in my first post.

1: The fat wire running to the starter with the 90 degree bend in it was pre-bent prior to install. If the starter is removed the 90 degree bend stays put. The #2 tefzel does not want to spring back.

2: The smaller wire to the back of the alternator (unfortunately no photo showing the wire lug) comes in the the back of the alternator at approx a 30 degree angle, down from the fore/aft run to the alternator output post. The terminal lug has a corresponding bend so the lug fits on the output post without straining the crimp connection.

Bottom line is this: the wires need to come off the lug end aimed in the direction they need to run. Otherwise, I agree, the wire/lug crimp area will be forced into position and be under stress. I have found it acceptable to bend the lug (if required) up to 90 degrees to get the wire pointed where it needs to go. Just don't try to straighten the lug out again if the wire routing changes during build or in the future......re-terminate the wire end instead.