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Another version of House batteries not charge while driving.....


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Don't know how long this has not been working, we don't have any big coach loads while driving,  I have noticed that when I do plug in after driving the coach batteries are charging at a very high rate...  Finally realized the are not charging via the alternator...  I have an IRD isolator delay ( Intellitec p/n/ 00-00629-120), mounter in the circuit/fuse board in drivers side front bay.   3 wires attach this to the board   ignition source:blue, relay coil:red, ground: black...   Per the service manual for part, when the voltage on ignition line is above 13.5 volts for more than 20 seconds the relay red wire will be activated...   That never happens for me...    

After little metering here is what I believe my issue is:   The ignition wire only get to 13.1 volts,  I check the chassis power stud on board and voltage is 14.2 volts.  It appears my ignition switched voltage has a loss some where (had similar issue with headlight voltage)...  So isolator relay is not switch on to activate the relay in batter compartment..  Hs anyone seen this issue?  

I have 2 solution in mind.... 

A) add a simple relay that switches chassis power to isolator delay, triggered by ignition feed, thereby supplying 14+ volts when engine is running, which should trigger the isolator relay...  

I have also read about chassis batteries not charging while on shore/generator power...  A little research I found monaco did make a upgrade to the ird to make it a bird..  unfortunately that is no longer available....   So thinking a second solution 

B) Add intellitec B.I.R.D. diesel 2 (p/n 00-00839-000),  as well as simple relay above to get full chassis voltage to isolator delay.  by adding the coach battery input to this device I will have a full function bird...  The generator pin is not needed since this function is downstream on relay line (see below)

One thing I did discover in researching this is the FRB board also has a relay right below the ird.  This deactivates the relay line when the generator is running, preventing any conflict between who is commanding the charging.  interesting to note if this relay is failing and not switching off isolator relay, can cause the alternator warning light to flicker due to overcharge detection...  

Jim D
2005 Monaco Knight 38PST

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Scotty, Vito,  interesting, I'll take a look...  Don't relish running a wire from back to front of coach...   I am going to patch in a relay to see if my theory works....  If repair gets bigger, I will look hard that the links you provided ...  


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  • 2 months later...

I'm late to the party here.  Did you get your problem resolved?  Mine did this and I had the same issue w that blue wire.  I jumped the blue wire to the chassis source in that bay.  BUT, I also had a bad battery.  I don't know which was truly the problem, but new batteries, new relay and jumped the blue wire and it all works fine.  I forgot to mention earlier I did replace the relay as mine was bad too.  But that didn't immediately fix the issue. Maybe check your house batteries closely too. 


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