House Batteries Not Charging

[Bill Heffernan]

We are out on our first trip of the year and our house batteries are not charging while on shore power nor do they charge while driving. All of the connections are good and clean. The battery disconnect switch is on. I recently cleaned up the Big Bird and noticed that it is not on. Nothing is lit on PCB 6. When I press the ISO RLY SW button, it immediately trips back off. Electrical is not one of my strong suits, this is as far as I'm able to get. Any thoughts/recommendations. As always thanks for the advice. 

[Frank Bergamo]

No green light on when plugged in, or on generator power is probably a board failure. No green light on when unplugged or generator not running is normal. Need to determine what is going on with above scenarios. If board is bad, a jumper from chassis bank to house bank positive terminals is a work around until you can get it working properly. Your batteries will not be isolated, but that can be managed accordingly. Hope this helps, good luck. Found this, it might help you,
When connected to shore power or when the generator is running you should have power to the #2 pin on the eight pin connector on the right side of the board. The #1 pin is ground and the #3 pin is powered on when you turn on the Ignition Switch. Pin #4 is from the battery boost circuit, Pin #5 is the Domestic power circuit. Pins #6 & #7 are blank. Pin #8 is a ground circuit.

The six pin connector on the top of the board powers up the relays. The left pin is Pin #1 and is ground, Pin #2 powers up the Big Boy Relay, Pins #3-4-5-6 power up the two Domestic Relays to the right of the Big Boy Relay. When working properly you should measure about + or - 4.6vdc on Pin #1 when the Board is powered up and the Big Boy Relay is working.

If the BB is powered up and running correctly, you should have around 4.5 to 4.8 vdc on pin 1 of the 6 pin connector. You should also have that same voltage on pins 1, 4, 5 & 8 on the 8 pin connector.

[Scott Shearer]

Bill,

I would first attempt to find out why the house battery bank is not charging while connected to shore or generator power.

When on shore or generator power, the house battery bank charges independently of the BIRD system (PCB6), drawing power directly from the inverter/charger. In fact, the house batteries will charge regardless of the position of the house battery disconnect switch.

First, verify that your inverter is set to charge mode and the remote panel is displaying a charge voltage. Then, you can follow the charging path by inspecting the large lugs located at the bottom of the rear run box. Charging current from the inverter enters the rear run box at lug #5, passes through the high-amperage circuit breakers, then continues to lug #4, on to the battery side of the house battery disconnect switch, and finally the house battery bank.

There should be charge voltage present at lugs #4 and #5, the high-amperage circuit breakers, the battery side of the house disconnect switch, and of course the batteries.

If there is no power at lug #5, check the output terminal (red cable) on the invertor.

Regarding rear run box PCB6 (BIRD-BCC), pressing the yellow ISO RLY SW on PCB6 will not lock in the Big Boy relay; the function is momentary, like the Boost Switch located on the dashboard. The Big Boy will not lock in until PCB6, pin 2 OR pin 3 on the 8-pin connector, sees 13.3-volts or higher for at least 12-seconds.

-Scott

[Bill Heffernan]

Thanks guys. Sorry for the slow response - internet went down at the park we are currently staying. I'm not finding power at any of the lugs. How do I get to the cable coming out of the inverter? The inverter thinks its charging, but it's not. For the time being, I've got a couple chargers on the batteries. Strangely, they are very slowly charging even though we are on shore power, it's almost as if there is still a draw on the batteries. Fortunately, we are only about 5 hours from home and should be able to make it without concern. Thanks again.

[Scott Shearer]

To check power at the inverter, remove the red and black caps that cover the large cables on the front of the inverter, take a reading between the two terminals.

When I said, “no power at lug #5”, I should have said less than charge voltage. Even if the inverter isn't charging, at the minimum you should still have battery voltage at lug 4, or 5 if the circuit breakers are not tripped. Also, you should have switched battery voltage at lug 3.

You stated that your “house batteries are not charging while on shore power nor do they charge while driving”. The only common thread between shore power and travel house battery charging is the cabling between the house batteries and the disconnect switch, but if that was bad, you’d have no domestic power in the coach. 

Are you sure that your batteries are good?

“I've got a couple chargers on the batteries. Strangely, they are very slowly charging even though we are on shore power, it's almost as if there is still a draw on the batteries.”

-Scott