Beeping Coach Battery Disconnect Switch

[Chinookers]

Any thoughts on this problem?

For some time now, the cab's overhead coach battery disconnect switch beeps and flashes when it is switched on and I start the engine. Once the engine has started the beeping stops. Seems odd, and logically unrelated, that beeping occurs when drawing current from the starter battery!

More recently the beeping has begun happening when parked and when drawing current such as running the water pump.

The coach batteries are fairly new (2.1/2 years) AGMs showing full charge.

Could this be faulty disconnect switch? Bad ground? What do you think? Anyone had a similar experience?

Thanks in advance.
Andrew
2003 Chinook Premier

[caconcourse]

It sounds like the voltage sensed at the LVD is marginal and detecting less voltage than the actual battery output. Turning on a pump will add current draw and may decrease the voltage slightly from floating to actual charge value. I think there are three battery cables going to the LVD (one big and two smaller). One of the smaller ones would be the sense wire for the LVD. I would try to measure the voltage at the ends of those wires and make sure they are showing full output voltage. If so the LVD may be deteriorating. I would clean the contacts of those wire connections to the LVD after checking. There is probably a ground wire to the LVD that may need to be cleaned up as well. I think those LVDs are pretty robust, and although they get blamed for a lot of problems, they are usually not broken.

I would also check the starter battery. If it is getting old, it may be using the house batteries to maintain charge, causing them to dip when starting because the separator is engaged for charging.

[lhalbert]

Mrs. Gabbi here...

This sounds something like what we are experiencing...sort of. On our 1997 Concourse - 2 new batteries replaced about a month ago - the rocker button (the "Coach Batteries On" switch) will mysteriously flip from the green "on" position to the neutral position. It is not flipping to the "store" position.

Once we push the light back to the green "on" position and put a small drain on the batteries, such as the water pump (sometimes even just a light), after just a few minutes the button trips again to red and we get the loud LVD beep.

A few questions:
1. Why is the rocker button tripping off? And shouldn't that be on unless we really are storing the van? It is our daily driver, so no need for storing it.

2. Any idea of what brand the LVD module is? I want to do a search for the LVD monitor so I can understand it better.

Thanks,
Lee-Ann

[caconcourse]

BUS_CBT_INST_180070e.pdf

(34.99 KiB) Downloaded 977 times

Here is the LVD installation manual with some detail. The rocker switch is momentary and essentially starts a timer (I think it is 30 or 60 seconds) that forces the batteries to connect until the timer expires, regardless of the battery voltage. Near the end of the timeout, if the battery voltage is too low (below 11.8V) the beeper goes off and you have to restart the timer to stay connected. If the battery voltage is high enough they will just stay connected. The model is SurePower 135001 and they don't make them anymore. Someone just gave one away on Facebook, so occasionally someone may have one after they replaced the disconnect switch with something else.

The LVD is actually pretty reliable, and most of the reported problems were traced to some other cause, like a bad ground connection or a loose battery cable connection. There is also a big (50Amp?) self-resetting circuit breaker between the battery and LVD that has been known to corrode and fail or cause problems.

[lhalbert]

Thank you Clay. So, a couple more questions...

1. Should the green battery “on” light (rocker button) remain on all the time (except when in storage)?

2. If trying to tighten a loose battery cable...do you mean where I have the batteries installed in the van (the storage area), or at the LVD? Is the LVD easily accessible?

3. If I go from most likely to least likely (think horses not zebras), what is my order to check? Least invasive to most invasive?

Learning is a lifelong process, isn’t it?

Thanks again,
Lee-Ann

[caconcourse]

Thank you Clay. So, a couple more questions...

1. Should the green battery “on” light (rocker button) remain on all the time (except when in storage)?

2. If trying to tighten a loose battery cable...do you mean where I have the batteries installed in the van (the storage area), or at the LVD? Is the LVD easily accessible?

3. If I go from most likely to least likely (think horses not zebras), what is my order to check? Least invasive to most invasive?

Learning is a lifelong process, isn’t it?

Thanks again,
Lee-Ann

Yes, the green light should be on as long as you are not in storage and the LVD is not tripped.

Here is the LVD wiring diagram:

The LVD is located near the floor behind the driver's seat and is not very accessible unless you remove the sofa. However you could probably get voltmeter probes on the terminals to make measurements.

Assuming the LVD is working, it looks like a pretty severe voltage drop between the batteries and the "SENSE" input (smaller red cable from battery to LVD). I would check the connection at the battery terminals and make sure they are tight. The sense cable is in the main bundle on the + side of the batteries. Working a little in the blind, you could also check the screw terminals in the LVD and make sure they are tight.

You can easily test the 12V voltage on each circuit in the "brown box" distribution panel. The DC fuses and terminals for each circuit are in the top right hand panel in the brown box. (If you still have the original Magnatek converter/charger, you should seriously consider replacing the guts with a new 3-stage controller, like the Progressive Dynamics PD4645). Measure the voltage at the batteries with no load and after turning on the water pump or something that gives you trouble. If the voltage at the battery doesn't drop significantly, the problem is in the wiring. Next measure the voltage at the DC distribution panel with no load and after turning on something. If the voltage is significantly lower than at the batteries, there is a loss in the wiring. If the voltage is normal (12-13V) and the LVD still trips, it could be the LVD, or a bad sense wire/breaker. (It is the Sense voltage that trips the LVD, rather than the Vin voltage itself even though both wires come straight from the battery)

Since the LVD is tripping, there is most likely a loss between the batteries and the LVD, which is only about 3 feet of cable. There are two cables from the batteries to the LVD: the large power cable (8 gage) which goes to the "Vin" terminal and the smaller "Sense" cable which goes to the middle terminal of the LVD. The Vin cable has a 50Amp self-reset breaker, and the sense cable has a 15Amp breaker. A faulty breaker may cause problems.

Another relatively common cause for these kinds of problems are bad ground connections. The grounds are found underneath the coach along the frame. The lugs sometimes corrode or come loose. There is a group of ground connections near the batteries, and two sets near the rear of the coach, one group on each side (near the dump valves, and near the generator).

Good luck. It's probably something simple, but tricky to find.

[lhalbert]

Thank you Clay. I see the steep learning curve ahead of me - and it will take a bit of time to climb it. Your responses are helpful as I work on all of this.

Lee-Ann

[chin_k]

I think Clay gives you a good start. I just want to emphasize that the resettable breakers would be the most likely culprits. As mentioned, the LVD is pretty solid, but the breakers are under the chassis, outside the battery tray. In mine, they are inside a white plastic cover that mounted onto the chassis with two screws. When I removed the cover, there were large amount of dirt and debris, and the breakers were partially corroded. I ordered replacement breakers with rubber cover, and/or relocate them somewhere better. I guess that Trail Wagon put them there so keep them cool, and/or making sure they are not going to ignite the hydrogen gas??? Just guessing here... Poor connections at the resettable breakers will cause voltage drop and trigger the LVD.

[lhalbert]

Hi Chin_k,

Thank you for this idea. Checking the breaker may be easier than accessing the LVD.

If it is this breaker, is that like a breaker in a house - that I just flip it back in place...(then go order a new one/ones)?

Lee-Ann

[caconcourse]

Hi Chin_k,

Thank you for this idea. Checking the breaker may be easier than accessing the LVD.

If it is this breaker, is that like a breaker in a house - that I just flip it back in place...(then go order a new one/ones)?

Lee-Ann

I think the breakers are something like these:

https://www.amazon.com/Amp-Automatic-Re ... B006PJI1YW

https://www.amazon.com/gp/product/B00JW ... FNRH&psc=1

Since they auto reset there is no open/close switch. I haven't seen mine, but I have seen pictures of a corroded 50AMP like the one above. Chin could probably provide information for the ones he replaced, and how to find them.