2008 Diplomat Chasse batteries not charging.

[David W]

Hello I'm new to the MH life and just purchased a 2008 Diplomat.  The chasse batteries will not charge while on shore power. I'm not sure what's happening while on gen or running.  Where should I start to diagnose the power issue? It's a 12 volt system with parallel batteries.  

[Doug and Nicki]

this may be the Big Boy solenoid in the rear run bay. That device controls when the batteries are charged. I have had to replace mine twice.

[cbr046]

On our 2003 Endeavor (sister to the Diplomat) the chassis batts don't charge on shore power either.  I switch the batteries off when I'm parked, but I'm all ears for a resolution (other than connecting a separate charger . . . . that's too easy).

The large solenoid (not a Big Boy on ours) is switched from the console, and it's a momentary switch for emergency starting . . . er, charging.  Batt Boost or Aux Start switch.

- bob

[waterskier_1]

Your 2008 Diplomat is equipped with a BIRD (Bi-Directional Isolator Relay Delay) which allows for charging both from the alternator to both sets of batteries (chassis and house) and from the Inverter/Battery Charger to both sets of batteries.  See page 177 of your Owners Manual.  

Generally, if the the solenoid the BIRD controls (sometimes called the Big Boy) does not engage or has bad contacts, then there will be no current (charging) going either way.  That means that your engine alternator would not be maintaining your house batteries going down the road.  

I'm not sure where that realy (solenoid) is located on your coach - it is the same relay that energizes when you hold down the BOOST switch on the dash.  Measure both sides of the relay (large cables) and if there is more than 0.2 volts difference (when either the engine is running or you are are shore power), the contacts are bad.  

  -Rick N.

[bobdinsmore]

It's possible your system was not designed to charge the chassis batteries while on shore power, which was the poor design for my 2000 Diplomat. You easily can add shore-charging with a Xantrex Echo Charger. There are other solutions but this choice is very simple, less expensive than other more elegant alternatives, and it takes away no original function. Installation involves removing three nuts from the batteries and mounting the unit on the wall in the battery compartment, period. IShore charging of chassis batteries always is a lively debate on this forum so you'll hear other opinions.

[David W]

Thank you everyone.  There is a Trombrtta 114-1211-020 solenoid in the battery compartment. Do you know how to test it? it does get hot to the touch. 

21 minutes ago, waterskier_1 said:

Your 2008 Diplomat is equipped with a BIRD (Bi-Directional Isolator Relay Delay) which allows for charging both from the alternator to both sets of batteries (chassis and house) and from the Inverter/Battery Charger to both sets of batteries.  See page 177 of your Owners Manual.  

Generally, if the the solenoid the BIRD controls (sometimes called the Big Boy) does not engage or has bad contacts, then there will be no current (charging) going either way.  That means that your engine alternator would not be maintaining your house batteries going down the road.  

I'm not sure where that realy (solenoid) is located on your coach - it is the same relay that energizes when you hold down the BOOST switch on the dash.  Measure both sides of the relay (large cables) and if there is more than 0.2 volts difference (when either the engine is running or you are are shore power), the contacts are bad.  

  -Rick N.

Thank you

[waterskier_1]

That Trombetta solenoid is the one I referenced above as a "Big Boy".  The two large cables connect to the chassis battery and the house battery banks.  When neither the engine nor shore power is present, the voltage to ground from either of those terminals should be the same a the battery bank they are connected (around 12.6 volts).  When the main engine is running, after a couple minutes, that solenoid should energize (it will be warm, almost hot).  The the two large cables should read the same voltage as the chassis batteries read (around 14.2 - 14.4 volts).  Both sides should be within 0.2 volts of the other.  Now shut the engine off, and connect shore power.  You should have anywhere from 13.4 to 14.4 volts (depending on what mode your charger is in - Bulk, Absorb or Float).  That voltage again should be the same (within 0.2 Volts) or each other.  The most common problem is dirty contacts.  You can disassemble the solenoid, and replace or clean the contacts.  They also make silver contacts that resist corrosion and pitting better.  Let me know the results of these tests.  Much less often, there is a problem in the BIRD circuitry (located in the Front Run Bay).

  -Rick N.

[klcdenver]

The big boy should be on the back wall in the same bay as your batteries. You can remove it and disassembly it and clean it up. This will usually get them back working.

[David W]

15 minutes ago, waterskier_1 said:

That Trombetta solenoid is the one I referenced above as a "Big Boy".  The two large cables connect to the chassis battery and the house battery banks.  When neither the engine nor shore power is present, the voltage to ground from either of those terminals should be the same a the battery bank they are connected (around 12.6 volts).  When the main engine is running, after a couple minutes, that solenoid should energize (it will be warm, almost hot).  The the two large cables should read the same voltage as the chassis batteries read (around 14.2 - 14.4 volts).  Both sides should be within 0.2 volts of the other.  Now shut the engine off, and connect shore power.  You should have anywhere from 13.4 to 14.4 volts (depending on what mode your charger is in - Bulk, Absorb or Float).  That voltage again should be the same (within 0.2 Volts) or each other.  The most common problem is dirty contacts.  You can disassemble the solenoid, and replace or clean the contacts.  They also make silver contacts that resist corrosion and pitting better.  Let me know the results of these tests.  Much less often, there is a problem in the BIRD circuitry (located in the Front Run Bay).

  -Rick N.

Thank you. Now I have a place to start. I just watched a video on the big boy and the isolator and it explained a 0lot.  

 

[1nolaguy]

10 hours ago, cbr046 said:

On our 2003 Endeavor (sister to the Diplomat) the chassis batts don't charge on shore power either.  I switch the batteries off when I'm parked, but I'm all ears for a resolution (other than connecting a separate charger . . . . that's too easy).

The large solenoid (not a Big Boy on ours) is switched from the console, and it's a momentary switch for emergency starting . . . er, charging.  Batt Boost or Aux Start switch.

- bob

Our 2005 Safari Cheetah also was not designed to charge on shore power, just the altinator. My solution was easy and inexpensive. I have a 4amp digital charger connected to the batteries using ring crimp connectors (not alligator clips). When connected to shore power i connect to the 120v outlet on my inverter, or I can run a 16 gage extension cord from another power source if needed. I have been using this setup mow for 4 years without issue, except do not leave the charge plugged into tour inverter if not on shore power. Leaving it plugged in will eventually drain your house batteries. Note: in a pinch you can also use this system and charge using you genny.VIKING 4 Amp Fully Automatic Microprocessor Controlled Battery Charger/Maintainer - Item 63350

[cbr046]

I looked at the Xantrex Echo . . . . While it only charges chassis batteries when the coach batteries are being charged it's $170!

Or maybe the $40 NOCO GENIUS2D and leave plugged in all the time.  The only time it will charge the chassis batteries is when hooked up to shore power, and there's 120V AC in the next compartment where the inverter is. 

Only issue is it running when boondocking off the inverter, but would only be a maintenance charge at that point.  https://www.amazon.com/NOCO-GENIUS2D-Direct-Mount-Temperature-Compensation/dp/B07W3QSMF9/

Maybe I'll put it on my list of "easy projects" . . . .

- bob

[Jetjockey]

I have the echo charger by xantrex and it works well. I have heard 3 owners lately a prevost,allegro and Monaco that experience your problem also.. I have never had an issue. I have a xantrex smart  shunt on my batteries so I can always monitor  charge to chassis and house plus current charge or draw..  I watch it bounce back and forth between the two systems as it charges them .. very easy to install and no issues with it doing its job.