House Batteries Not Charging While Driving

[Gary Donges]

Beaver 2006 Patriot Thunder. House batteries don't seem to be charging while driving. Chassis batteries charging fine. The house batteries are really run down by the time I shut down for the day and the Magnum Remote indicates a bulk charging cycle when I connect to shore power. After an hour or two, remote indicates a full charge cycle completed. The Automatic Generator Start system has activated while underway after 5 or so hours of driving without prolonged stops when engine is shut off. Engine shut down only for brief stops for fuel or a snack. Have a Magnum Energy MS Series 2000 Watt Inverter/Charger. When I initially noticed the problem, checked inverter and found the reset button on AGS module was red, so reset, light went green and still is. I've checked battery and inverter connections and obvious breakers on the inverter itself and they seem to be fine. Green lights are lit on inverter.

Batteries are Lifeline AGM's and are less than 5 years old.

If anyone has had a similar problem that has been successfully resolved, what was the fix?

[Guy Pryor]

I have not had your problem but from your description I would suspect that your alternator is not performing up to standard

[Joel Ashley]

First off for the many new coach owners here:  re. alternator, it was not meant to hit the road after dry camping and recharge house batteries.  That’s a major cause of alternator failures.  Recharge with your genset prior to starting the engine.  The load of 4 to 6 discharged deepcycles is much more than our standard alternator can deal with, and is it’s sure-fire demise.

That out of the way, and assuming your alternator hasn’t been abused in that manner or you’ve not dry camped, Gary, check your Magnum panel over the door, aka. “the remote”, and make sure it’s set for AGM batteries and not wet cells or gels.  Some owners change battery types and don’t realize the inverter needs to be programmed for that, otherwise for example the inverter’s charger may try an equalizing charge phase that’s meant for wet cells but may not be helpful on others.  Ditto for the dip switches on your solar controller.  The inverter should have little to do while you’re on the road and is unlikely the problem here.

After ascertaining all that, your ‘06 coach’s BIRD controller may have a bad connection, pinched wire, or other failure.  It’s the Intellitec Bidirectional Isolator Relay Delay on the door in the cabinet over your batteries.  The controller operates the Big Boy, the large solenoid in the middle front of the cabinet.  If the alternator is good, the controller on the highway makes sure the chassis bats get up to 13.3 volts, and then switches charging to the house set.  If your alternator is bad your two chassis (starting) batteries won’t be up to snuff either, and it may only be a matter of time before they let you down at a fuel stop or somewhere inconvenient.  You should use a voltmeter to check the voltage at first the chassis set with engine running, and after a bit the house set.

At a campsite plugged in or when on the generator, the BIRD charges the house set up first to 13.3 volts and then does the chassis pair, just the reverse of when the engine is running.  Also possible is a bad Big Boy solenoid, as some threads here have recently discussed.  It may not be switching over to charge the house set when told to.

Joel

[Guy Pryor]

Thanks

[Joel Ashley]

To mitigate any possible misunderstanding from the way I worded my previous post, the BIRD does not do the charging itself.  It merely acts as an automatic switch (controller), deciding which batteries are charged by which source.

Joel

[Gerald Farris]

Gary,
From your description, your inverter, and engine alternator are both operating properly. Your issue is being caused by a malfunction in your "BIRD" system and you need to repair it or have someone with RV electrical experience service it for you.

Gerald

[David T. Richelderfer]

BIRD - Bi-directional Isolator Relay Delay

It's Bi-directional functionality allows for the charging current to go from 1> shore or generator POWER thru the inverter to the coach batteries and then to the chassis batteries, or 2> alternator POWER to the chassis batteries and then to the coach batteries.

          POWER > inverter > coach batteries   >>>BIRD>>>  chassis batteries
                                                                  Bi-directional
                                        coach batteries   <<<BIRD<<<  chassis batteries < alternator <<< POWER
 

[Scott Shearer]

Hi Gary,

We have had a similar issue with our 2006 Thunder, the house batteries were not charging while driving and, less obvious, the chassis batteries were not charging while on shore or generator power. Our problem was caused by very corroded Big Boy relay. I disassembled and cleaned the relay and it worked fine for two years, cleaned it again and, for now, it’s working.

If your coach is the same as ours, your Big Boy relay is located in the Rear Run Box. The Rear Run Box is located on the passenger side of the engine compartment (right above the hydraulic reservoir). The Big Boy relay is controlled by PCB (printed circuit board) #6, also located in the Rear Run Box. PCB #6 controls the Isolation Relay (Big Boy Relay) and the 12 volt house disconnects. There are two small yellow buttons on the circuit board, one will energize the Isolation Relay (Big Boy Relay) and the other will cycle the 12 volt disconnect relays. There is a green LED that is lit when the PCB is sending a signal to the Big Boy coil. The push button switch is labeled ‘ISO Relay SW’, the LED is labeled ‘ISO Relay ON’.

When energized, the Big Boy Relay will hum and is fairly warm. You should see nearly the same voltage reading on both of the relay large terminals, if not, there is a good chance that the contacts are corroded.

The Big Boy relay is not rated for continuous duty so use caution when using the ‘PCB’ button to energize (same as the boost switch on the dash).

[Bill Sprague]

I still have the .pdf files for the BIRD and Big Boy.  If you can't find them in the tech library, I can send them.

[Peter Becker]

I was having the same issues with my house batteries.
Replaced all 6 a few weeks ago and now they charge and hold a charge fine.

[Gary Donges]

Thanks to all for your valuable input.