House batteries not charging from chassis system while driving
 

I have checked voltages before and after driving a four hour stretch with batteries partly drained. Voltage level goes down consistently. So, they are not charging from the chassis system.

Where do I start?

Please tell us more about your RV. Are you sure it ever charged the house batteries on the alternator? Do you have a boost switch on the dashboard to tie the two battery systems together for emergency starting? Does it work?

Some older MHs used diode isolators to charge the house batteries. Look for one and see if, while running, there is over 13.5+ volts on all 3 terminals.

Here is a link to what they look like.

https://www.dbelectrical.com/wolthuis...61&size=medium

Thanks bflinn. It is a 96 Newmar mountain aire.

No, I am not sure it ever charged the house system.

Yes, it does have a boost switch in the dash panel. I do not think it works, though I have not measured voltage with the switch on.

Thanks twinboat. I will look for an isolator.

When you press the battery boost switch, you should hear the solenoid clicking. Track it down and check fuses on it and that both large terminals read 12 v (+) the voltages from each battery group.

That makes sense. I hear nothing when I press the battery boost switch. That gives me somewhere to start. Awesome.

isaac,
What Bluefinn is referring to is basically a "dual duty" solenoid. In that, is has the ability to perform two operations, independent of each other. In one op, it links both sets of batteries, house and chassis, together so that if and when your chassis batteries are too weak to turn that diesel engine over for starting, you get help from the house batteries. That solenoid will manually close, when you push the "Auxiliary Boost" switch on the dash.

The second op is, through the specific wiring, it automatically closes when the engine is running and, then it will send some of the charging current to the house batteries.

Now, questions:
1. Does your coach/chassis/charging system have this particular solenoid?
2. If it does have it, where is it, and is it performing as it should?
3. Can it malfunction? If so, how does it malfunction and, how often?

Well, first off, yep, you'll have to determine IF your coach/chassis is equipped with this type of system. I'm not familiar with your make/model/year of coach so, I can't help there. You see, there's all kinds of charging link-up systems out there that link the house batteries to the engine charging system. So, the smart thing do here is, either get out the books on your coach/chassis and find what you have or, call your MFG and or chassis maker and see if maybe they can help.

Now, if you do have it, then where is it so that so you find it and begin a test or two to see if it's functioning as it's supposed to, in both operations.

And, speaking of that, does it malfunction? Yep, it sure does. And, based on a few threads on this forum and, a few on other RV forums, it has a somewhat reputation for foul-up. How often does this happen? Well, on some coaches/chassis', like ours, an '04 Itasca Horizon 36GD with the C-7 330HP CAT, with 65K on the clock, it's only happened once in 11 years. And the symptoms were exactly what you're presently experiencing, no house battery charging while driving down the road.

Can it be fixed? Well, yes, it depends. Inside those solenoids are a set of contacts. They are heavy duty contacts that, over time, and, hundreds and hundreds of cycles, can get "arc burn" on them. When that happens, you get a sort of carbon between the contacts and that results in a "NO-Contact" between them. When that happens, you've lost your ability to utilize the house batteries as help when you need them.

And, it looses its other and, most needed function too. And that's the ability for you have your house batteries being charged, when your engine is running. So, can it be fixed you ask? Most gents on here won't bother. They'll simply go purchase another one and install it and call it a day. But, me being me, I like to see how things work. So, I dissected mine. It's simple. I drilled the rivets out that held it together. It pops open to reveal the working parts and, the tarnished contacts.

Well, with a bit of work, a dremel, some sand paper, and, some small screws to put it all back together and, it's been working like new for a good couple of years now. I check the voltage at the batteries every so often to make sure, while the engine is running.

So, sorry for the long explanation but, I thought you'd like to know how things work, if you have this kind of system on board your coach.

That is one type of battery link/charging system. As stated, there's plenty more of them.

And, if and when you find out, just what kind of system you have, and, get it fixed, if I were you, I'd check the actual output of the alternator, at the house batteries, when the engine is running, on a somewhat frequent basis. That way, you'll know for sure, just what kind of voltage is actually getting to both your chassis and house batteries.

Its one of those things that, while I use the inside panel on battery checks, I also use my volt-ohm meter right at the battery posts (of all batteries) to see just what's getting to them. Good luck.
Scott

I had the same issue so I cleaned all the terminals and followed the negative cable to where it attached to the chassis. It was buried under spray on foam cleaned it all off removed negative cable cleaned underneath. I then reattached and painted over connection. It cured my charging problem and also a couple of over intermittent problems.

Great explanation. Okay, some searching and here is what I have.

The first image is a relay controlling the solenoid. It has labels ignition, coach batt, relay coil and ground. Second image is the solenoid.

I am assuming a bi directional solenoid is the same as a dual duty solenoid.

https://photos-3.dropbox.com/t/2/AAB...size=2048x1536
https://photos-5.dropbox.com/t/2/AAD...&size=1024x768

This solenoid clearly connects the house and chassis systems.

I pulled all the fuses and they look fine. Any idea how to test it? I would like to know whether it is the solenoid or the relay.

Here are the images

https://dl.dropboxusercontent.com/sc...iry=1457628525

https://www.dropbox.com/sc/tnbp6zv8q...zaQdnAGyvXQHua

Measure the voltages on all four connections. Post those here.


The small terminals are the on/off control. To get the solenoid in the activated mode there must be battery voltage 12.5 volts or so on one of the small terminals and zero on the other small terminal.


The control voltage comes from a couple of sources. You can prop you emergency start button or have someone hold it down. You may need your ignition switch in the run position.


If the engine is running there should be voltage on one of the small terminals.


If you are plugged into shoreline there should be voltage on one of the small terminals.


If the generator is running and the engine is running there MAY not be voltage on one of the small terminals. Some systems have a generator sense and will not allow the generator and alternator to charge the engine batteries at the same time.


Once you have voltage on ONE of the small terminals the solenoid should be active. The solenoid may be warm or hot to the touch if you have been plugged into shoreline for several hours.


Now measure the voltage on each of the large terminals. If they are not exactly the same voltage then the solenoid has bad contacts inside and this is a very common problem. They can arc and pit or just grow junk inside.

The photo shows a BIRD (Bi-Directional Isolator Relay) which is part of the system that controls your battery charging system. It actually requires 13.1 v to trigger the relay. It also has a built in time delay, it doesn't operate instantly. See the spec sheet linked below.

https://www.intellitec.com/assets/pdf...-00362-000.pdf

Isaac W, start by going into the attached Newmar link and scroll down to Battery Systems. This information is specific to your Newmar system which in many cases will differ from other manufacturers.

https://www.irv2.com/forums/f103/orig...ods-18509.html