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Battery Maintenance Contactor (solenoid)

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I'm talking not about the disconnect switch, but the contactor that is supposed keep the house batteries charged while driving and also keep the chassis batteries charged while on shore power. It's the same contactor that connects the house batteries to the chassis for emergency starting with the Batter Boost switch on the dash.

I have a 2009 Monaco coach and while wintering Texas this year, I discovered that my chassis batteries were down to where they wouldn't start the engine. I always start my engine about once a month while parked. I then tried the Battery Boost switch and still nothing. I started investigating the cause and found I could hear the solenoid snap in loud and clear. After scratching my head for while and thinking this a new coach only a little over a year old, that contactor should be good. Wrong!!! :):rolleyes: I tested for current on the out going lead while the contactor was made and had nothing. I then removed the contactor and went an purchased a new one, installed it and it worked fine.

Curiosity got the best of me, so I drilled out the rivets disassembled it to see what's inside. I thought the contacts might be burned, but they were fine but coated with a layer of corrosion. This contactor is located in the battery compartment and there no corrosion on any of terminals outside the contactor and I try to keep the compartment clean. How that battery gas can get into the contactor is a puzzle. I cleaned up the contacts and reassembled the contactor and now keep it for a spare.

I owned an 05 Monaco with the same set up, and had a similar problem, but I never investigated it so I assume the same thing. I also talked with a friend while I was working on the contactor, he commented he has the same problem. He also owns a late model Monaco.

My solution to prevent this from happening again is move the contactor out of the Battery compartment into the compartment next to it and extend the cables as needed.

Any other Monaco owners out there with the same problem??

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Solenoid failure is not that uncommon.

And if you can locate it outside the battery compartment without adding too much length to those large-gauge cables that is great. Properly gusset them if going through a bulkhead, as they are un-fused.

I will make a comment on one of your statements-- you say you start the engine once a month while parked.

STRONGLY suggest that you not start any diesel engine unless you can drive it at least 25 highway miles. If the OIL, not just coolant can not attain operating temperature, you are doing more harm than good by starting. And there is no way that a diesel can reach oil operating temperature without a load on it.

Also, when parked in one place for an extended period of time, make sure fuel tank is full to minimize condensation.

Brett

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Solenoid failure is not that uncommon.

And if you can locate it outside the battery compartment without adding too much length to those large-gauge cables that is great. Properly gusset them if going through a bulkhead, as they are un-fused.

I will make a comment on one of your statements-- you say you start the engine once a month while parked.

STRONGLY suggest that you not start any diesel engine unless you can drive it at least 25 highway miles. If the OIL, not just coolant can not attain operating temperature, you are doing more harm than good by starting. And there is no way that a diesel can reach oil operating temperature without a load on it.

Also, when parked in one place for an extended period of time, make sure fuel tank is full to minimize condensation.

Brett

I'll take that under consideration. I am aware that I won't reach operating temp, but I thought would still be better to circulate the oil in the engine and transmission once in while.

Bill

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Hi Bill,

I agree with Brett. Once the coach is parked, the automotive components go to sleep and are not disturbed until the coach is to travel again. I do run the generator once a month for 1 hour. The generator is put under load via the HVAC and HWH. This is for the benefit of the electricity generating part of the generator not the automotive part. I shut off the HVAC and HWH for about 5 minutes before shutting down the generator. This does allow the automotive part of the generator to come up to operating temp.

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To All:

Moving the contactor to outside the battery box will not solve the problem. I have replaced at lease six of those relays for the problem you just discribed. The problem is that most of the time the contactor is connected very little current is flowing (both sets of batteries are charged) and the contacts then corrode. The corrsion also is generated each time the contact make contact.

The better solution is to replace the contactor with one that has silver coated conatcts. They are a little more expensive.

An example is the Bear Family 12 volt Contactor PN 114-1211-0200.

It can be purchased from Mur Cal Inc

sales@murcal.com Price is approximately $33 plus tax and shipping.

Telephone 661-272-4700 Larry Fox Monaco 04 windsor

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To All:

Moving the contactor to outside the battery box will not solve the problem. I have replaced at lease six of those relays for the problem you just discribed. The problem is that most of the time the contactor is connected very little current is flowing (both sets of batteries are charged) and the contacts then corrode. The corrsion also is generated each time the contact make contact.

The better solution is to replace the contactor with one that has silver coated conatcts. They are a little more expensive.

An example is the Bear Family 12 volt Contactor PN 114-1211-0200.

It can be purchased from Mur Cal Inc

sales@murcal.com Price is approximately $33 plus tax and shipping.

Telephone 661-272-4700 Larry Fox Monaco 04 windsor

Thanks Larry, I'll keep that in mind. The one I put in cost more that double the price you quoted, and I think it is in the Bear Family. I have a spare right now, so I'll keep an eye it.

Bill

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I have the same problem with my 08 Safari Simba diesel pusher. At present I am using a small BATTERY MINDER cube charger to keep up the starting battery--The battery compartment needs more ventilation--will order new solenoid and try for more air in the compartment as charging fumes are highly corrosive that's why the connections are covered with red anti-corrosion grease from the factory--too bad Monaco went with a cheap contactor as their desire to save a few cents can ruin the reliability of an otherwise well designed coach.

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REPLACED CONTACTOR WITH ONE THAT HAS NEW SILVER CONTACTS NOW EVERYTHING WORKS CORRECTLY --- ENGINE CHARGES BOTH SETS OF BATTERIES WHILE RUNNING AND INVERTER - CHARGER KEEPS BOTH SETS OF BATTERIES FULLY CHARGED WHILE CONNECTED TO SHORE POWER - ALL AUTOMATICALLY WITH NO MANUAL INTERVENTION. WHAT A WONDERFUL THING WHEN EVERYTHING WORKS CORRECTLY !!!!

THANKS TO ALL !!!

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