Alternator field breaker tripping

Dterhaar

Do you know what model starter you have?

Some have a piggy back solenoid and some don't.

Web

It was a good question Jerry.

Web

wireweinie said:

It was a good question Jerry.

Web

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My forgetful nature made me want to look at one and see if they have been there since the beginning of time and I was too dumb to notice:lol:


Jerry

I don't go as deep in the weeds as you do, usually, on the design stuff, but I put spike diodes on EVERYTHING with a coil. Even little accessory relays get them. As you pointed out lots (maybe most?) installs work fine without them but for about a dime a diode, it's not worth the hassle to not put them in. Also, my view is that that spike today may not knock out your radio but repeated spikes will eventually catch up to it and shorten it's life. Or maybe just that one, unusually large spike like that 'third wave' theory?

As to fancy clamp or sensing circuits, For aircraft use, I feel that lower tech is better. You can make an extremely sensitive, fast acting circuit to protect the rest of the board, but in a fairly 'noisy' electrical environment it's just going to cause more headaches than it will prevent.

Web

wireweinie said:

I don't go as deep in the weeds as you do, usually, on the design stuff, but I put spike diodes on EVERYTHING with a coil. Even little accessory relays get them. ...
Web

Click to expand...

That's a good idea. Every once in a great while, my old-school turn and bank will trip the OV clamp. It has its own switch.

Well it looks like the spike diodes did the trick, I installed one on the master and starter solenoid this morning (neither had one) and flew it several times today and no field breaker tripping! Why build a $100k plane and not install $10's worth of parts to make it right?? Just an over sight I guess.

Thanks everyone for all the help and suggestions!


Dave

B and C is a good supplier of both Master Relays and Starter Relays. This photo shows their Master Contactor with its external mounted diodes.

I’ve been following this thread and had nothing to add because I knew Web and others had nailed it. I’m just smiling because I started designing circuits in the early seventies and remember drawers filled with 1N4004 diodes and the recommendation to apply them liberally to anything with a coil in it.

Rich.

Like leather boots and 1911's, some things are hard to improve on.

Web

When I first got to Silicon Valley they had just cut down the last apricot orchard. My co worker had put a cap across a relay coil to absorb the inductive energy(like points ignition), but it delayed the pull-in. I figured a reverse-biased diode would do the job. By the end of the week Randy was gone and I was hanging with the boss after hours. The next month I flew with Dave Kilbourne, who, 8 years prior, showed us you could make an oversized waterski kite and run down a hill (Mission Ridge, behind the Tesla plant) to launch it. Good times. Now a year goes by in a month.