House Batteries charging question.

[Okie pilot]

I have a Monaco 2004 Signature. When the motor is running should it charge the house batteries? Mine is not. If it is supposed to, what do I need to do? My generator will charge my house batteries but the engine does not.

Thanks in advance.

[Randyman1]

Sounds like you need to clean or replace your BigBoy solenoid in the rear run box. Mine was doing the same thing when I bought it three and a half years ago. I learned on this forum all about it and they were right. Bought mine new on eBay for around $160 I think.

[BFlinn181]

Typically, a battery isolation relay should connect both chassis and house batteries when a charging voltage (+13.4v) is detected. It should connect when alternator, shore power , or generator is providing power. Take voltage readings on both battery groups when unplugged, engine running, on shore power, and with generator running. This will tell you the status of the relay and if it's connecting. You could also check with the dashboard battery boost switch, which activates the battery isolation relay.

[Okie pilot]

Originally Posted by BFlinn181

Typically, a battery isolation relay should connect both chassis and house batteries when a charging voltage (+13.4v) is detected. It should connect when alternator, shore power , or generator is providing power. Take voltage readings on both battery groups when unplugged, engine running, on shore power, and with generator running. This will tell you the status of the relay and if it's connecting. You could also check with the dashboard battery boost switch, which activates the battery isolation relay.

How do you check with the boost switch. Thanks for your help

[Okie pilot]

Originally Posted by Randyman1

Sounds like you need to clean or replace your BigBoy solenoid in the rear run box. Mine was doing the same thing when I bought it three and a half years ago. I learned on this forum all about it and they were right. Bought mine new on eBay for around $160 I think.

Thanks I'll do some checking when I get home.

[BFlinn181]

Originally Posted by Okie pilot

How do you check with the boost switch. Thanks for your help

Seeing a voltage increase on both battery groups when the engine or shore cord is connected. The relay also has terminals you can check with a meter to see if it's connecting or not. If everything is quiet, have someone press boost switch on the dash while you listen at the relay to hear it click.

[Scottybdivin]

I was having the same problem. I briefly pressed the boost switch and it started working properly. You can tell if it is working by the voltage on your inverter's remote. The voltage will go from 12.? up to 13.4+. Kind of reminds me of the time we used to tap on a starter solenoid to get it unstuck.

[Outbound]

I just replaced my battery isolator, had 14.3 volts in (center terminal) from alternator and only 14.3 volts out on one terminal to motor batteries, should have same volts going out to house batteries, easy fix.

Outbound
2002 Monaco Executive

[distaff]

Lots written this, but let's summarize the basic symptoms:

• Are the house batteries charged by the alternator (you have answered this as no)?
• Are the starter batteries being charged by the generator/shore power?
• Does the boost switch cause the two 12V systems to connect (do the voltages equalize when it is pressed)?
• Are the batteries and the connections to them in good condition?

There are several different systems that can all misbehave:

• There is the BIRD system that controls the relay by monitoring the voltage levels on the two 12V systems - pretty sure the '04 Sig had the BIRD system
• There is a very inexpensive relay that connects the output from the BIRD system and the Boost Switch to the relay
• There is the relay itself - the "BigBoy" - it can get dirty inside and stop transmitting power and it can burn out (usually from holding down the Boost Switch)
• The inverter can cause issues - mine was settling to a voltage on "float charging" that was not adequate to trigger the BIRD system so on shore power so the starter batteries would drain.

If you answer the first questions we can help point you at one of the second systems to look for the problem.

[Okie pilot]

Originally Posted by distaff

Lots written this, but let's summarize the basic symptoms:

• Are the house batteries charged by the alternator (you have answered this as no)?
• Are the starter batteries being charged by the generator/shore power?
• Does the boost switch cause the two 12V systems to connect (do the voltages equalize when it is pressed)?
• Are the batteries and the connections to them in good condition?

There are several different systems that can all misbehave:

• There is the BIRD system that controls the relay by monitoring the voltage levels on the two 12V systems - pretty sure the '04 Sig had the BIRD system
• There is a very inexpensive relay that connects the output from the BIRD system and the Boost Switch to the relay
• There is the relay itself - the "BigBoy" - it can get dirty inside and stop transmitting power and it can burn out (usually from holding down the Boost Switch)
• The inverter can cause issues - mine was settling to a voltage on "float charging" that was not adequate to trigger the BIRD system so on shore power so the starter batteries would drain.

If you answer the first questions we can help point you at one of the second systems to look for the problem.

House Batteries are not being charged by the alternator.
I don't know if the start Batteries are being charged by shore and or generator.
I have never used the boost switch.
I bought 4 new batteries last July so all connections are good.

Sorry I am not much help. Had the motor home about 1 1/2 years. I have almost all the bugs worked out and have learned a bunch about it but just realized it probably should keep the house batteries charged after a long drive. Just been using shore, gererator, and solar to do so. But would really help on quick 1 nighters not to run gererator.

Thanks you for your help.

[YC1]

Welcome to the forum.

This is a very common issue and there is tons of stuff on it. I am not trying to brush you off but here is a link to some of it. If you type the word BIRD in the little google box above and to the right it will take you to the following page.

I am an electronic geek so enjoy learning the variations of the setups. Someone will come along with your exact model and know where the "Big Boy" is located. Many can be repaired and some are just better replaced.

https://www.google.com/search?q=bird...earch=irv2.com

[Randyman1]

OkiePilot, if you have never done anything with your big boy solenoid, I guarantee you that is your problem just get one. It's a maintenance item that nobody ever does anything with so you are probably due for one.

[distaff]

Okiepilot - do you own a multi-meter? If you don't you will either have to buy one and learn how to use it, or get a repair tech to work on it. No two ways around this one. A multi-meter is your friend if you own a motorhome.

[Outbound]

Photo's of 2002 Monaco Exec big boy compartment with layout print, not sure if yours resembles photos, this may help.

Outbound
2002 Monaco Executive