Forum Discussion

Rhigley's avatar
Rhigley
Explorer
Aug 07, 2015

Battery

Today I had to jump my 2005 e 450 because it showed no power when I turned on the key. Got it started and then turned on the power to the coach and started the generator and ran the air in storage. After about 20 minutes I turned off the motor and disconnected the neg. side of the battery. Went back to the coach and shut off the gen and turned off the battery. Went back to the cab and turned on the key and was able to start the engine??? Pulled the negative off the house battery and I had no more power. Do I have a problem?
  • Rhigley wrote:
    Do I have a problem?


    Good answers so far on the main problem. 2 additions:

    The isolation relay might be "normally closed" and need a trickle of power from the truck battery to keep it open and isolated. Or to put it another way, disconnecting the truck battery might have caused the "emergency" bridge relay to close on it's own.

    The 20 minute run that you did is NOT long enough to recover a full charge on the previously dead battery. It is not good to leave them in a discharged state. I suggest that you need to use a smart charger on all of the batteries, individually, to be sure they have a full charge.
  • It could be that you have a BIRD a Bi Directional Isolator Relay Delay,look in your battery bay.

    There are some brands that come from the factory with them already installed,Fleetwood products such as mine and some Winnebagos come from the factory with a BIRD and if the battery disconnect,on the power panel, is left on it will connect both batteries when not on shore power or generator.

    It operates by sensing the voltages on both batteries.
    When either of these voltages exceeds 13.3 volts for
    approximately 1 minute, which happens when either battery
    is being charged, the control will close the isolator solenoid,
    connecting the two batteries together, charging them both.
    (Normal charging voltages are from approximately 13.8 to
    14.4 volts.)
    After the solenoid has been closed, the system continues to
    sense the voltage. If the ignition switch is off and the battery
    voltage drops below 12.8 volts for approximately 1 minute,
    which might occur when the converter is heavily loaded,
    the solenoid is opened to prevent the chassis battery from
    being discharged by the coach loads. When the voltage goes
    above 13.3 volts again for approximately 1 minute, the solenoid
    closes again. Thus always keeping the Coach as well as Chassis battery charged. Regardless of the parasitic draws on the chassis battery that run it down while sitting unused.
  • It sounds as though your battery isolator isn't isolating when it should, so it's more or less acting as though the emergency start is always engaged.
  • Some coaches have an emergency start switch that wil allow you to draw on the house batteries if the chassis batteries are dead.