I thought I just killed my chassis batteries last time out, but have found out I am getting no chassis battery charge off the shore power or generator.  I noticed my battery cutoff switch does not light up, but functions. My manuel says there's a fuse in the back closet for this, but I checked it out and nothing is blown.  I believe I have 2 relays and 2 solenoids that go to the big boy, to allow charge to the chasis batteries.  Am I correct on that?  Monaco told me to check the gray box in the battery compartment, but I don't have that.  Any ideas would help.

Thank you

Do you have an Echo Charger to charge the chassis batteries?  There are 2 - 20 amp fuses in the pos and neg line . Mine blew when the unit got wet, thus allowing the chassis batteries to go flat.

Hi Jeremy,

I believe we have it narrowed down to a relay, I'll know in the morning. I have 1 30 amp fuse and it's good.

Thx for your time.

Make sure you charge the chassis batteries with the generator or shore power before you start your engine, or the alternator will be overloaded, and probably die, as mine did 400 miles later !!

Absolutely, will do.

Thx
bv

Also check the ground wire on the BIRD relay. Mine was loose and prevented the relay from working.

I also, had the same problem on the main ground wire.  The factory never swaged the connector, in our case the wire fell out after 4 years.

Thanks for the input. What we found is, the Big Boy opens the current from shore power to the chassis batteries after a 3 volt drop in the system, which is about 10 volts. The Big Boy was not opening the gate, if you will, to allow the chassis batteries to charge after the voltage drop.

I'm confused.  The battery isolator/combiner solenoid is suppose to disconnect the batteries from one another, if the voltage of the one battery hits a low threshold and the other battery is not at a voltage high enough to be a charge voltage.  That threshold should be about 10 volts.  There are several configurations.  Fundamentally, when the charger is supplying charge voltage, somewhere around 13.5V or more, the solenoid combiners the batteries so they are all charged.  When the charger is off or not working, the battery's voltage is somewhere near 12.8V.  For some solenoids, at this voltage or less, the solenoid is in combined operation until either battery bank drops to some low level, maybe 10V. For other solenoids, the absence of charge voltage will disconnect the battery banks from each other.

Gil
80 Contessa 42

On the coaches that use combiner solenoids, the two battery banks are only connected together when one of the battery banks is being charged at a voltage of 13.3 volts or greater, and disconnect the two battery banks if the voltage on the combined battery banks drops to a level that would indicate that they were no longer being charged. I think that is around 13V.

If the battery banks stayed combined until the voltage dropped to 10V, you could not start you generator or engine either one to recharge your batteries because a 12V battery that is at 10V is totally dead. Also if you discharge your chassis batteries to 10V, they will have a very short life. Most non deep cycle chassis batteries that are run down to 10V, then recharged 3 or 4 times, are ruined. If you discharge your deep cycle house batteries to 10V on a regular basis, their life expectancy will be cut in half.

Gerald  

Gerald, did I not explain this correctly? When my mechanic got on the phone with the Monaco tech advisor, he questioned the 3 volt drop as being the trigger point to charge both sets of batteries. We don't think it's that much.

Gerald, you are correct.  It was a CRS moment for me.

Blue Seas makes a great combiner isolator that takes a fraction of the space our systems use.  They also have some good technical information.  Their product combines battery banks at 13.0V and disconnects them at volatges below 12.75V and above 16.2V.  If I every have to replace mine I'm going with this marine system: http://bluesea.com/category/2/productline/388

Gil

Bernie,
There is no 3V trigger designed into your combiner system. The system is basically designed to combine the battery banks when charging at a voltage above 13.3 and disconnect them when the charging stops and the voltage drops to about 12.8.

Even though there is not a trigger for voltage spread, there are minimum and maximum voltage readings that control the activation and deactivation of the combiner solenoid. If your solenoid does not disconnect the battery banks below 12.7V, the system is malfunctioning.

Gerald  

Replaced the Big Boy and we are now getting a charge to the chassis batteries from shore power.

Thx
bv

What is a  Big Boy?