Battery Boost Solenoid Not Helping With Flat Chassis Battery

[Wakesupremo]

My 1989 sunsport has the boost solenoid in between the coach and chassis solenoid. I had a flat chassis battery yesterday and tried the boost button but nothing happened. Luckily I managed to get started after a while but, how does the boost function work?

 

[Chuck v]

The boost solenoid (blue circle) connects the two battery banks, house/coach (red) and chassis (green), together for starting the engine in the same way the BIRD controller uses that solenoid to connect those banks under the right conditions when the engine is running to charge the house battery when under way.

Your wiring will be similar to this, although you may not have a separate inverter battery bank) which in my case requires the use of two solenoids -- a Main IRD and a Coach IRD:

Chuck

 

[Wakesupremo]

Thanks Chuck. Once again your info is brilliant. However, I seem to have a problem whereby once I try to start the engine it 'clicks out; the solenoid so I get no power to the starter. I think its a dead battery issue but, Again, I don't understand how this can 'click the solenoid out' as that means the polarity is reversed!!!!

 

[Chuck v]

Wake,

There are two kinds of solenoids shown in the diagram above... Those marked IRD are continuous duty solenoids that will remain actuated as long as the coils are energized. The other two "disconnect" solenoids are latching units that stay in the most recently selected state until a momentary pulse of the other selection is given...

Do you have a picture of the solenoid you are concerned about so we can identify the type? Does it look like those on this drawing?? The green and red highlighted solenoids are latching types, and the one in the blue circle is a continuous duty style that is onnly actuated as long as the voltage is present on its coil...

Note that the triggering voltages for the latching relays are not shown above...

Chuck

 

[Just two]

Not sure if it helps. I recently added back the solenoid that connects the battery system to enable start assist. The 12 volt coil portion was connected to the driver’s switch using brown wires.
This is on a 2021 5210.

 

[Wakesupremo]

Thanks again Chuck. Its the one circled in blue. Im not sure that its working but. Today my wifes at home so she can press the button while I test the solenoid. However the big issue is this, when I turn the key to crank, the chassis solenoid unlatches and drops power to the starter. I don't see how this can happen when it is a latching solenoid and , in order to do this, the polarity must change. These are the pics of my set up.

 

[Wakesupremo]

I've tested it all out and everything seems to work as it should. It was possibly the battery being flat all along but, after driving 10 miles to the filling station I'd have thought it would have charged up!!!

 

[Chuck v]

Thanks for the description and the pictures -- it helps quite a bit.

Depending on the level of discharge and the condition/age of the batteries, a short drive will perhaps not be sufficient to charge them much. You would need a DC ammeter of at least 400 amp reading range to verify the charging currents. Fortunately, most of the digital ones nowadays are clamp on styles so they are pretty easy to use. Mine looks like this:

As to the latching relay -- it does require a reversal of polarity of the applied momentary triggering signal to the relay coil terminals, and most control panels use a momentary user switch with a center off position and a spring return to that position. set of terminals. The wiring diagram shown below indicates how these controls are typically wired -- and I have found most coaches closely follow the wiring colors shown as well.

Chuck

 

[Wakesupremo]

Thanks once again Chuck. Yes I have a DC clamp meter but, as I have only just charged the battery up the alternator won't be putting anything into it anyway. It still puzzles me as to why the chassis solenoid kept 'unlatching'. I really can't understand why that would be. I have also wondered if my problem is heat soak to the starter not an actual flat battery!

 

[Chuck v]

The way the latching disconnect relays are constructed they cannot change state unless a voltage is applied to the field winding -- and the field winding is only driven by the momentary rocker switch in the diagram shown. Anything else means you have a wiring error or control harness short someplace...

I suppose the internals of the Intellitec relay could have a failed mechanical component, but I have never heard of it happening... The below drawing shows the relay in the 'latched on' position and the rod magnet is blocking any movement of the plunger to let the high current contact washer spring open.

 

[Wakesupremo]

Thanks again chuck. Somehow it turned off the coach battery but I don't know how. The red light on the intelitek went off. I had to press the switch again to power it back up!

 

[Boze33]

Hi everyone.
Coincidence???
I am still trying to understand ALL THE INTERCONNECTED ASPECTS OF THESE COACHES
I literally just had a similar issue on a 2001 GS Yellowstone Bus model 8407. My White-Rodgers solenoid would click as if trying to actuate and charge, but wiuld click "off" again quickly. Plugged into shore power.
One thing to check is the remote panel inside the coach to check DC amps. Mine was only reading 10. Thought the solenoid was sticking. And wouldn't charge the house batteries. What I think it was ... the temperature sensor was placed on the "wrong" battery terminal. It was put on the incoming wire from the charger battery lug. Thus getting "hot" . It would trigger the shut down. I moved it to a negative terminal on the other battery and so far 2 days in, the Solenoid has "clicked" and stayed "closed". Charging looks good and my DC amps on the remote panel jumped to 30 on the initial bump up charging. Has since settled back to 10, I guess more of a trickle charging now.
Chassis batteries were also dead as a foir nail so had to buy new ones. Once they were installed the system seems to be operating normally now.
****I hope!!!

 

[unom]

The solenoid is likely powered from the house batteries. You may have a tripped breaker/blown fuse.

I’d hazard a guess that a 1989 does not have a latching solenoid and that the solenoid is only energized when the switch is pressed. If the electrics have been updated then it’s possible it’s latching.

 

[Wakesupremo]

Hi unom. Yes it is a latching solenoid and, hopefully, now that i have replaced the chassis battery, we won't have any more issues for a while!!! Thank you.

 

[THenne1713]

My 1989 sunsport has the boost solenoid in between the coach and chassis solenoid. I had a flat chassis battery yesterday and tried the boost button but nothing happened. Luckily I managed to get started after a while but, how does the boost function work?

Crawl under and check all grounds to chassis? Yours 10yr idler than mine, ground screw popped head off from rust on mine.

 

[THenne1713]

Crawl under and check all grounds to chassis? Yours 10yr idler than mine, ground screw popped head off from rust on mine.

Esp.. near solenoids