Battery Boost Switch

[David 70]

The boost switch on the dash has never worked since I got this coach. I see there are two solenoids in the electric compartment in the step well. One has just one primary engagement wire on it. I assume it is for the house disconnect. I have tried to feel of it while I use the switch by the door but with both of the solenoids mounted on a thin piece of aluminum it's hard to tell for sure which one is moving. The other solenoid has two primary engagement posts. I am thinking it is the charging/boost one. Is this one also supposed to connect the house batteries to the chassis batteries while hooked in to shore power?

[twinboat]

One solenoid will be the house battery disconnect.
That may have a smaller cable on one of the larger posts. Most are latching relays and need 2 primary terminals. They latch and unlatch by reverse polarity.

The isolation/boost solenoid will have starter size cables on both sides and be contiounus duty. It closes while the engine is running to charge the house battery on the road and closed when you hit the boost switch.

Some have one and some have two primary terminals. The single primary terminal models ground thru the base.

If this doesn't clear things up, take a picture of the solenoids and post it.

[wolfe10]

Use your voltmeter to verify what solenoid does what/what is working or not working.

[edgray]

The dash switch should be a momentary switch that must be held down to connect the house batteries to the cranking battery. It is not intended to keep them connected and therefore has nothing to do with shore power charging of the chassis cranking battery.

[cbeierl]

Page 5 (of the pdf) of your Chassis Wiring Installation diagram shows the solenoids and their wiring.

[David 70]

Both solenoids have heavy cables on both posts. When checking with a meter it shows 12v on all four posts with no 120v and the engine shut off. The dash switch is a momentary and when I have had dead chassis batteries and pushed it nothing happens. I have used jumper cables to jump it though. Do those solenoids give trouble. I have the house batteries out of it now so will have to check and see where I have power on the posts.

[David 70]

Originally Posted by cbeierl

Page 5 (of the pdf) of your Chassis Wiring Installation diagram shows the solenoids and their wiring.

I will have to study that a little closer. Those diagrams are really small and difficult to read.

[twinboat]

One of the cables the isolation solenoid will have chassis 12 volts on one side and house 12 volts on the other.

Since they will not be exactly the same, use a digital meter to read the voltage at each side and each battery.

With no shore power, the disconnect will,have house voltage on one side and nothing on the other if off. If on, it will have the exact same house battery voltage on each side.

Looked at the schematics, the single primary terminal solenoid is the boost/ isolation solenoid.

And yes they fail often.

[cbeierl]

Also take a look at page 2 of the Automotive Wiring Diagram for your coach. When the engine is running or the Battery Boost switch is activated the solenoid should connect the chassis and coach battery banks together, allowing the alternator to charge the coach batteries.

On a 2000 coach I would not expect shore power or the generator to charge the chassis batteries (unless a previous owner has modified things). A good solution is to add a Trik-L-Start to keep the chassis batteries charged whenever the coach batteries are being charged. It can be installed right at that solenoid where connections to both battery banks are available.

[cbeierl]

Originally Posted by David 70

I will have to study that a little closer. Those diagrams are really small and difficult to read.

You can zoom in on all of the pdf diagrams--that helps a lot.

[David 70]

Originally Posted by cbeierl

You can zoom in on all of the pdf diagrams--that helps a lot.

Thanks for the diagrams. I had not seen those specific diagrams when I downloaded the wiring diagrams for my coach. I have the ones that have all the wiring and they are really hard to see. I will do some checking on my coach later today when it gets above freezing al though I have the coach batteries out for the season so this may wait for final remedy until spring.

[David 70]

Originally Posted by cbeierl

Also take a look at page 2 of the Automotive Wiring Diagram for your coach. When the engine is running or the Battery Boost switch is activated the solenoid should connect the chassis and coach battery banks together, allowing the alternator to charge the coach batteries.

On a 2000 coach I would not expect shore power or the generator to charge the chassis batteries (unless a previous owner has modified things). A good solution is to add a Trik-L-Start to keep the chassis batteries charged whenever the coach batteries are being charged. It can be installed right at that solenoid where connections to both battery banks are available.

These are the ones I have already and they have a lot of wires. to decipher.

[tderonne]

Many, MANY, threads on the subject.

This one has a couple picture that identify which solenoid is which without having to decipher the wiring diagrams.

[US1]

Originally Posted by David 70

.......The dash switch is a momentary and when I have had dead chassis batteries and pushed it nothing happens. ....... Do those solenoids give trouble..

Had same problem with mine this spring. Dash switch did nothing. Replaced solenoid and all worked great. A little research showed that yes, this solenoid is known to go bad often. I dont know if it is because whenever the motor is running, this solenoid is energized so to charge both chassis and house batterys. Possibly this continuous energizing is why its is a common failure item??? IDK