Boost Relay Stuck

[twinboat]

To be clear, the relay ( solenoid ) on the right is the Boost or Aux Start AND BIRD relay. It is controlled by the BIRD controller OR the dash switch. It has the large battery cables, necessary for boosting a low battery.

The relay on the left is the disconnect relay. The cables comming from it are to small for carrying boost current, but fine for supplying the power to all of the small circuit breakers it feeds.

From your description, it sounds like the boost relay is activating and sticking on its own. Is this the case ? Or are you trying it multiple times ?

Even if stuck ON, it shouldn't be getting hot, unless the pull in coil has current going thru it.

You need to find out if the small wire controlling the solenoid has power when stuck ON. If it does, unhook the wire on the BIRD controller, marked relay, and try it.

If the converter isn't running, the engine isn't running and you have no solar panels, the BIRD shouldn't be powering that relay.

I've seen that type of solenoid stick ON, but not repeatedly or without activation, like you describe.

[harris155]

If the contacts are pitted and not making a good connection the relay will overheat. This may cause the relay to bind.
At times quite a bit of current goes through these relays equalizing the voltage between battery banks.
Look at the cable size.

[harleyjt]

Originally Posted by twinboat

To be clear, the relay ( solenoid ) on the right is the Boost or Aux Start AND BIRD relay. It is controlled by the BIRD controller OR the dash switch. It has the large battery cables, necessary for boosting a low battery.

The relay on the left is the disconnect relay. The cables comming from it are to small for carrying boost current, but fine for supplying the power to all of the small circuit breakers it feeds.

From your description, it sounds like the boost relay is activating and sticking on its own. Is this the case ? Or are you trying it multiple times ?

Even if stuck ON, it shouldn't be getting hot, unless the pull in coil has current going thru it.

You need to find out if the small wire controlling the solenoid has power when stuck ON. If it does, unhook the wire on the BIRD controller, marked relay, and try it.

If the converter isn't running, the engine isn't running and you have no solar panels, the BIRD shouldn't be powering that relay.

I've seen that type of solenoid stick ON, but not repeatedly or without activation, like you describe.

Thanks for the reply. No, its not self activating. I didn't realize I had said that. It sticks sometimes when activated with the Boost switch. At least now when it does stick, it seems to un-stick on its own after some period. I've not found a wiring diagram for this exact system. The closest thing I find is for the diesels, but I think it has to be close to the same in this regard. When the boost switch closes, coach B+ is sent to the solenoid pull in coil. The coil is already grounded so it energizes and the batteries are then connected together. It appears there is also a wire from the BIRD module labeled solenoid that can also feed 12v to the solenoid. I guess this is how it manages charging. I think 007 may have a good idea on iron filings or possibly other debris causing the solenoid to intermittantly stick.

You have a good point on the control wire. Next time it sticks, I'll disconnect the wire from the BIRD module and see what happens. I guess it could be a module issue. I have caught it with the control wire getting 12v. I checked the dash switch, but not the module. I'll check that. Thanks again.
jt

[Qwert66]

To save energy (battery power) the BIRD module (for dual charging purposes from the alt or converter) automatically closes the solenoid (when 1 of the 2 battery banks drops slightly low) by energizing the coil in 2 steps. First it gives it 12+vdc to slam it closed then it drops the voltage down to appx 5-7vdc to hold it there while not heating up the coil.
The boost switch simply overrides the module and momentarily applies the 12+vdc to the coil.

This solenoid can be disassembled buy removing the nuts off the 2 large threaded posts and 2 small posts and very carefully bending the metal tabs back on the base. Then the bakelight cover can be slid off the 2 large threaded posts exposing the contacts for cleaning and inspection. I would not recommend doing this very often due to the tabs fatigue.

A simple resistance test with a vom across the 2 big posts can tell you a lot about the condition of the contacts (open, fully closed, in between needing cleaning)

By its nature of operation for tieing in slightly discharged battery systems it works fine.
For designed use of connecting 1 charged battery bank to a dead battery bank is asking a lot from the contacts in my opinion and I would recommend instead to use a portable charger powered from the generator or power pedestal instead of that boost switch if you have that option.