Charging System

[Basil]

Our 2018 Seneca has suddenly has a charging issue. When plugged in to shore power or when the generator is running it no longer charges the starting batteries. Also when the engine is running it no longer charges the coach batteries. I am assuming it is the one problem but not sure what it is. We are 6 hours away from the nearest dealer so iys not an easy trip to the dealer to have it diagnost. Any ideas.

[JimD]

There is a relay that connects the batteries together. Older rigs had a simple relay/solenoid that energized with the ignition switch. It would allow coach batteries to be charged from the alternator.

Apparently many newer rigs come with a special bi-directional smart relay that allows charging in both directions. It senses battery voltage and charges the starting battery until certain conditions.

As I have the old style I can not offer troubleshooting tips for the bi-directional version. But that is where your problem is. Best guess is that it is mounted under the hood probably up high against the back.

[Basil]

I will see what I can find Jim thank you

[RVermont]

If yours is the m2 the isolation module is located in the battery bay. I will see if I can grab a photo of it tomorrow and post it then.

[Basil]

Awesome thank you

[SloPoke]

Also might check the Circuit Breaker that is on top of the chassis batteries. These are the batteries that Start the Freightliner. Behind the panel right below the door opening on the drivers side. There are three breakers.. two small units and a larger one (the one to check - it has a small handle that pops out on the side, not very visible from the opening.

[GCAT9110]

What was the state of charge of the batteries, were they discharging or <12v?

[Basil]

The motor home batteries will discharge if the unit is not plugged in or the generator is not running. We discover the problem on our way home from a weekend trip when after stopping the steps would not retract due to low voltage. The main breaker on our generator had failed so we had no generator power. We had to disconnect the steps and retract them manually. As soon as we got home and plugged the unit in to power the steps and levelers worked.

[RVermont]

Sorry did not get a chance to take a photo of the actual unit but this is a photo from the web. Goggle precision circuits isolation module. I have tried to attach the trouble shooting guide but not sure if it will come through. If not just goggle precision circuits battery isolation module and click on the one pictured then you can locate the troubleshooting manual. As slopoke said check the chassis battery first.Battery-Isolation-Manager-Trouble-Shooting (2).pdf

[Basil]

Thank you so much for the information

[Basil]

Thanks for all the information it turned out to be a relay on the chassis batteries

[SloPoke]

Originally Posted by Basil

Thanks for all the information it turned out to be a relay on the chassis batteries

Can you be more specific on which one? Where is it located?

[Basil]

It was on the top of the batteries in the battery compartment under the driver side cap steps

[SloPoke]

Originally Posted by Basil

It was on the top of the batteries in the battery compartment under the driver side cap steps

If it was this? This is a 100A Circuit Breaker that is in-line with the "Battery Isolation Module" (BIM) that is controlled by battery voltages and can be engaged by the white switch on the dash. If your Senecs sits for a while and your Chassis batteries are discharged, you will have a tough time starting.

There are also cases where the BIM switch on the dash is pushed and the house batteries vs chassis batteries are going to draw more than 100A to charge the others, it has tripped our breaker before.

[Basil]

Yes thats it not sure but I think it may have had something to do with the failure of our generator breaker. It all happened at the same time. The breaker on the generator would not reset

[tljwYaki]

Originally Posted by JimD

There is a relay that connects the batteries together. Older rigs had a simple relay/solenoid that energized with the ignition switch. It would allow coach batteries to be charged from the alternator.

Apparently many newer rigs come with a special bi-directional smart relay that allows charging in both directions. It senses battery voltage and charges the starting battery until certain conditions.

As I have the old style I can not offer troubleshooting tips for the bi-directional version. But that is where your problem is. Best guess is that it is mounted under the hood probably up high against the back.

***
My 2012 FS31 has to be started at least once every 7 days now that it's gotten colder here in VT. During the summer I had start it about every 10 days. I have a trickle charger connected but something is drawing the battery down. Bought it used; previous owner connected so many things, only the wires were left. Getting some tech help when I get back home to try and undo/redo whatever is under the dash..what a mess!

[GCAT9110]

Originally Posted by SloPoke

If it was this? This is a 100A Circuit Breaker that is in-line with the "Battery Isolation Module" (BIM) that is controlled by battery voltages and can be engaged by the white switch on the dash. If your Senecs sits for a while and your Chassis batteries are discharged, you will have a tough time starting.

There are also cases where the BIM switch on the dash is pushed and the house batteries vs chassis batteries are going to draw more than 100A to charge the others, it has tripped our breaker before.

I have a 2015 Seneca, where is this white switch located on the dash?