Trombetta solenoid post-mortem

[John Canfield]

This morning I replaced the Trombetta solenoid with the Blue Sea #9112.  I was able to disassemble the Trombetta quite easily and unfortunately I do not see a 'smoking gun.'  The Trombetta contacts were in excellent condition, so there was no issue with a crust build-up on them.  The coil resistance measures 8.1 ohms with my Fluke digital multimeter which means the coil is drawing a continuous 1.68 amps at 13.6 volts applied.  In comparison, the Blue Sea #9112 nominal hold current is 110 ma (0.11 amps).

The Trombetta coil was obviously showing the effects of being quite hot due to discoloration on the coil form.

You can look at the pictures and draw your own conclusion.  I don't have one at this point.

[Jim Godward]

John,

The current draw seems high to me and the discoloration indicates excessive heat in the coil.  I suslpect if you attempt to unwind the coil, you will find shorted windings somewhere in the many turns.  As to what caused it, there are lots of small things that set it up, crossed windings, a nick in the varnish insulation and lots more.  I have seen many over the years.  My last one was the solenoid on a transfer switch in the MH.

[AA4WP]

FWIW, that's is the same thing I thought (without reading the first reply).  I suppose you could rewind your coil; I remember having rewound a HV transformer in times past (you know, for tube type rf makers).  I suppose you could get some high current wire for that. I cannot even remember the name of it...was is Nyclad???...with some fancy space age coating.   Worked just fine for the time I had the amplifier.  Just a thought.

Wendell

[Jim Godward]

Regular enameled transformer wire should be adequate but the thought of hand winding several thousand turns of No. 36 or such wire does not appeal to me.  I doubt it can be done reliably without an automatic coil winder machine.  I sure wouldn't even try it unless my life depended on it and even then I would try for another solution.

[John Canfield]

I think I'm done with Trombetta and have no interest in rewinding the coil    I remember playing around with various transformers over the years and unwinding them to see what made them tick - didn't put them back together, though 

The Trombetta solenoid is extremely dumb compared to the Blue Sea products.  The Blue Sea #9112 I used for a replacement can monitor either terminal post (or both) and operate when it detects a voltage of about 13.6 volts and will drop out when the voltage falls to 12.6 volts.  So if the charging source fails, at least your battery banks won't be all tied together.  The Trombetta operates strictly from the yellow (+) and white (-) coil wires and does not sense voltage on the terminal posts.  When the engine is started, 12V (13.6 actually) is applied to the coil and stays there while the engine is running.  12V is also applied to the same two coil leads when the Battery Boost switch is operated.

I'm creating a web page of the solenoid replacement and I'll have that done this week.

[Pubtym]

I think I'm done with Trombetta and have no interest in rewinding the coil    I remember playing around with various transformers over the years and unwinding them to see what made them tick - didn't put them back together, though  

The Trombetta solenoid is extremely dumb compared to the Blue Sea products.  The Blue Sea #9112 I used for a replacement can monitor either terminal post (or both) and operate when it detects a voltage of about 13.6 volts and will drop out when the voltage falls to 12.6 volts.  So if the charging source fails, at least your battery banks won't be all tied together.  The Trombetta operates strictly from the yellow (+) and white (-) coil wires and does not sense voltage on the terminal posts.  When the engine is started, 12V (13.6 actually) is applied to the coil and stays there while the engine is running.  12V is also applied to the same two coil leads when the Battery Boost switch is operated.

I'm creating a web page of the solenoid replacement and I'll have that done this week.

John,

Excellent presentation, dissection info..and photos.

This type of failure data goes a long way to save folks money....now to determine the cause of failure on this one..(cause and effect)

Thanks for your effort here,

Charlie

[Art In Mobile]

Great photos John!
My Voyage had the old style coil & I could readily see my problem. On yours I can't see anything that would make me see a problem. Around 8 ohms is where most coils read so coil was all right. Thanks for the info. You gave us something to scratch our heads about. I installed the new one with silver contacts but if I have any more problems I will go your way. Art

[Pubtym]

Great photos John!
My Voyage had the old style coil & I could readily see my problem. On yours I can't see anything that would make me see a problem. Around 8 ohms is where most coils read so coil was all right. Thanks for the info. You gave us something to scratch our heads about. I installed the new one with silver contacts but if I have any more problems I will go your way. Art

Art,

Let us know if you have problems with silver.

Spec coil Resistance on Trombetta Bear is 7.7..silver vs copper contact gives twice the designed cycle life 50,000-silver versus 25,000-copper. John's is copper. I believe the clue to John's component failure centers around the clear signs of excessive internal heat....and the cause of that excessive internally generated heat.

http://www.trombetta.com/cm/pdfs/bear-family.pdf

Personal opinion: It's not money time for me to change horses yet (Trombetta to Blue Seas) when cause of sick horse is unknown now. I currently do not think the current horse (Trombetta) is dumb....sick..yes...dumb...no.

Charlie

[Just Lou]

The Blue Sea #9112 I used for a replacement can monitor either terminal post (or both) and operate when it detects a voltage of about 13.6 volts and will drop out when the voltage falls to 12.6 volts.  So if the charging source fails, at least your battery banks won't be all tied together.  The Trombetta operates strictly from the yellow (+) and white (-) coil wires and does not sense voltage on the terminal posts.  When the engine is started, 12V (13.6 actually) is applied to the coil and stays there while the engine is running.  12V is also applied to the same two coil leads when the Battery Boost switch is operated.

John, what you now have (with the Blue Sea #9112) is a solenoid with the BIRD function, found in the Intellitec and RV-CP battery control centers used by many other RV manufacturers, incorporated within the solenoid.  For the price, let's hope the solenoid itself is much improved.

[Pubtym]

John, what you now have (with the Blue Sea #9112) is a solenoid with the BIRD function, found in the Intellitec and RV-CP battery control centers used by many other RV manufacturers, incorporated within the solenoid.  For the price, let's hope the solenoid itself is much improved.

Lou,

Great explanation of "intelligent" and very costly (needed?) Blue Seas technology.

I think I'll stay with dissection of Trombetta CAUSE before I change horse to Blue Seas BIRD.

Charlie

[Jackliz]

Ummmmm, John,
What is this Trombetta solenoid's function?

TIA,
Liz

[snowwing]

John
I'm thinking that after four failures you have done the right thing. After my third one fails I think I will do the same thing!
Ron

[ReM]

For what it might be worth---

I have yet to have a problem with the original stock Trombetta solenoid in my 2004 Journey--

 But-----------  I have some diodes in my tool box for the project although I have been too lazy to install them--


(I did have a problem with the relay that drives the solenoid however--  loose connector on it)


What I do that may be different from most is to always use the dash mounted switch to bridge the batteries while starting-- This should help (and apparently has) to keep the contacts functioning--  Can't speak to the reported failures due to coil heat as I haven't experienced a failure yet--

ReM

[Becks]

John...Thanks once again for the good info. I'll add it to my file.

[John Canfield]

Excellent presentation, dissection info..and photos.

Charlie - the kind words are greatly appreciated 

What is this Trombetta solenoid's function?

Liz - this relay/contactor/solenoid (goes by several names) bridges or electrically connects the house and chassis battery banks together so the engine alternator can charge all of the batteries.  Without this solenoid, only the chassis batteries would be charged and if you run a lot of stuff on the inverter (like we do), you can seriously deplete the house batteries without them being charged while running down the road for hours.

[Jackliz]

O.K. John.
Thanks for the explanation. Good luck with the new solenoid.


Regards,
Liz