MEXICOWANDERER wrote:
I was asked to comment on this. One condition was not mentioned. And it is a condition that will burn any solenoid. If the test is not verified then solenoid burnout is assured -- even 300 amp modeks.
The solenoid must not remain engaged as the engine is cranked. Check that the small ignition post goes dead as a doornail as the engine starter motor is cranked.
A five dollar fender mounted plastic body solenoid is more resistant to burnout at 700 amps rating than a hundred dollar 300 amp continuous duty solenoid. Why? Because when the engine is being cranked that so I avoid no longer utilizes 12 volts. Try 10 volts. Weak pull in, chatter and contact arcing.
Putting in a flywheel diode reverse orientation will help correctly connected solenoids live longer. More info about flywheel diodes on the web.
Verify correct connection to ignition B Instead of Ignition A
I am minus a laptop so no more posts
David ... I think you may have really hit on something above regarding the pull-in coil voltage on the solenoid dropping during engine cranking ... which may cause solenoid point "chatter" while high current is being passed between the solenoid's points. Point chatter will of course cause arcing across the points and subsequent corrosion of their surface. This corrosion built-up on the points during uses will over time increase the resistance across the points, which in turn lowers the charge voltage that the coach batteries are exposed to from the engine's alternator. Hence -> under-charged coach batteries when you arrive at the campsite after driving for awhile.
I'm on my 2nd Trombetta solenoid in over 10 years. I attributed the failure of the original stock solenoid and the 1st Trombetta solenoid to the points becoming corroded over time. However, I couldn't understand why the 1st Trombetta solenoid - with it's silver coated contacts - would be subjected to corrosion. Perhaps even silver can degrade/corrode from any arcing that low pull-in voltage based point chatter may cause.
Here's the Trombetta solenoid model that I'm on the 2nd one-of in our motorhome:
https://www.trombetta.com/wp-content/uploads/2019/07/bear-family.pdfPerhaps this would be a more robust Trombetta to use that I didn't know about - or didn't exist - when I began using Trombetta solenoids in our motorhome:
https://www.trombetta.com/wp-content/uploads/2019/07/TR-19105_PowerSeal-ContDuty_SS-v4.pdf
