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After four (or was it five?) Trombetta solenoid
failures, I'm ready for something different


May, 2010 update:

The new solenoid is still working and hopefully will continue to do so! Winnebago engineering says the Trombetta product is suitable for this particular application, but the fact is we have had several failures of the product and I'm not the only one reporting failures. Trombetta does have different models of this solenoid, some with silver contacts, so perhaps a more expensive Trombetta product would have had a longer life-span. In any case, I'm very happy with the Blue Seas product.

Aug 2009

So what is this solenoid-thing anyway? When the engine is running, or when you depress the "Battery Boost Switch", both house and chassis (engine starting) battery banks are bridged together. With the engine running, both banks are being charged from the engine alternator. If you have a bad chassis battery bank and can't start the engine due to low battery voltage, you can operate the 'boost' switch and bring the three house batteries on-line and paralleled with the chassis batteries (three house batteries in my Horizon - don't know about yours) to hopefully turn the engine over and have a successful start.

How do I know if the solenoid-thingy is working or not? Pretty simple - with the engine running, both battery banks (house + chassis) should read about the same voltage (the house bank might read 0.1- 0.5 V lower at first.) After about an hour (or less) of operation, both house and chassis battery banks should read about the same voltage (around 13.6) - if your house bank is reading say 12.6 volts and your chassis batteries are reading 13.6 volts, then you have a problem!

Your problem could be spelled T-r-o-m-b-e-t-t-a... (Pictures here of my sick solenoid - exact solenoid issue not determined)

After researching several possibilities, I knew I wanted a Blue Sea product. Blue Sea caters primarily to the marine market, but boats with large diesels and large battery banks perfectly fits our coach situation. My replacement solenoid of choice was the model #9112, but it has been discontinued and replaced by the Automatic Charging Relay line of products. I ordered a model 7620 from Peter Kennedy Yacht Service, but Blue Seas couldn't fill the order in my time-frame, so I would up with a 9112 anyway (for another $40 I might add.)

Materials, tools needed for the replacement:

A caution:

If you attempt this project, be confident that your abilities and skill level will meet the demands required. Go slowly, especially if you don't disconnect your chassis and house batteries. Disconnecting mine is a real tedious job, so I would rather take a lot of time to safely deal with live 12 volt primary wiring (it has the capability of inflicting burns if shorted to ground producing an arc and could possibly damage electronics - be SAFE and be CAREFUL!!) If my caution has produced any doubt about your abilities in your mind, please have a good tech do the work - it will be money well spent!


Let's get started with a "before picture:


Before picture - stock arrangement

This is located in my electrical bay at the top rear of the compartment. Looks a little crowded now, but we will move stuff out of the way to make more room

Cables moved out of the way

It is a subtle change, but I installed a drill-screw at the top of the picture and used a couple of zip-ties to pull a mess of cables to the top and out of the way

Cables removed from the solenoid and bagged

CAREFULLY remove the cables and insulate them in a thick/strong bag and zip-tie them out of the way. The cable on the right is not hot and is the feed for the house circuits

Old solenoid removed

The Trombetta solenoid is removed and we're ready for the Blue Seas product

Blue Seas #9112 solenoid

Blue Sea model #9112 replacement (now discontinued, but still available as of Aug., 2009)

The #9112 is now mounted

The 9112 is mounted and ready for cable installation

Almost finished

All is hooked up. I have since disconnected the wire from the 'battery boost' switch on the dash to the #9112 orange control wire - the yellow wire taken off the original Trombetta solenoid has 13.6 volts applied to it when the engine is running which defeats the 'smart' nature of the #9112 to only operate when it sees a sufficient voltage from the charge source

Completed project

And one last view of the completed project!