Community Forums

ArkansasRomr · 06-01-2019, 06:33 PM

Hello my Monaco friends, or anyone who can help. I’ve spent well over budget at my RV repair shop and I’m trying to knock out this issue myself.

Problem- Chassis batteries not charging properly from shore, generator or engine running. The batteries (Interstate Batteries) were replaced 9/18 so I wouldn’t think they would be bad this soon.

One known issue- the solenoid that opens the battery boost from the house batteries is bad. Would this BE my problem? I can start the engine by simply bypassing the solenoid with jumper cables or connecting the house to chassis batteries.

Help me out guys. I know there is a lot of great knowledge out there from folks who do most of their own work.

Thanks in advance

Romr

richard5933 · 06-01-2019, 06:40 PM

Have you confirmed that the terminals are clean and tight? That your ground cable(s) are solid and properly attached? Quite common for ground cable going to the chassis to look good but be rotted inside or have a bad connection.

8.3Oilbuner · 06-01-2019, 07:45 PM

Hi Romr; I am going to try help so bear with me. I have an 01 Windsor and I think our systems are close in design. No sure if the Dynasty's have the big boy relay for passing the charging voltage to the chassis batteries, but I think the Dynasty does and the Windsor does not. I think it is located in the engine compartment in one of two electrical boxes there. It is not an uncommon problem. Have read about here many times. For far better knowledge than I have try putting your question in the search box at the top right of this page and I am sure you will have lots to read. I have read that you can use a jumper on the big boy relay to see if it is not engaging. I know others will have the correct answer here as they have dealt with this problem before. Just some info to maybe help you get started. When you do find the problem please let us know what the fix was. Have a great evening.

ArkansasRomr · 06-01-2019, 09:36 PM

Hey Richard,

I’ve inspected but haven’t taken them off and you are exactly right. I will do so.

Thanks

ArkansasRomr · 06-01-2019, 09:39 PM

Hey 8.3oilburner,

I am trying to get a couple pics for you to see but I bet they are the same.

Do you know how to attach pics to these posts?

ArkansasRomr · 06-01-2019, 09:46 PM

Will do and thanks

8.3Oilbuner · 06-01-2019, 10:11 PM

Hi Romr; Sorry, never have attached photos. There are instructions somewhere in this forum but not sure where. I am the dum dum when it comes to this procedure. Someone may chime in on how to post pictures.

K7JV · 06-01-2019, 10:20 PM

You said that the chassis batteries won't charge from the main engine? That is interesting. The Big Boy, or whatever other form of BIRD should not keep the chassis batteries from charging from the coach engine alternator. That should be a "fail safe" mode of operation. I hesitate to say too much, because the differences from year to year, make to make and model to model can be huge!

It is normal for the engine alternator/regulator system to charge the chassis batteries whenever the engine is running.

It is normal for the coach generator or the shore power to charge the coach batteries whenever there is a 120 VAC source available to the inverter/converter.

Any cross charging from one source to the other battery is generally controlled by some kind of device utilizing relays, often with some kind of control logic to determine when the connection between the two batteries is made, or in the most basic of systems, power diodes for the benefit of one battery or the other.

If what you say is absolutely correct, then you may have two problems. You could have a charging issue from your engine alternator that could be the alternator, the regulator, the chassis battery, or any of the cables and connections that are a part of that system. You could also have an issue with the relay that ties the two batteries together when the proper conditions are met, or even with the control device that tells that relay to energize to tie the batteries together.

There is a lot of talent on this forum, and hopefully you will be able to ferret out the problem. But I have given you a few things to look at, depending on your comfort level with mechanics and electrical and electronic test equipment. I hope you find the problem soon.

ArkansasRomr · 06-01-2019, 10:53 PM

Thanks Jim,

That was good stuff and I will chase them down. My dad passed the mechanical/electrical to my brother..... I was always off playing ball somewhere.
Now I know I should have stuck my head under those hoods at least a little bit!

I’ll let you guys know if I find the culprit. Electrical issues are always a bug hunt.

twinboat · 06-02-2019, 02:22 AM

Some pictures will help but if your MH is using a diode type isolator and its bad, you will get no charging from the alternator to the chassis or house batteries.

It wills be a rectangular, finned box, with 3 stud type terminals. They are usually right near the solenoid you are jumping and the cable from the solenoid go to it..

YC1 · 06-02-2019, 07:41 AM

http://www.metrotrekkers.org/utility/electrical.htm

Here is a fun site to help you learn the systems. You will have to get to know yours of course but playing with the site you can learn a lot.

K7JV · 06-02-2019, 08:14 AM

I am coming back to the fact that you said your chassis battery isn't charging from your engine. That is a concern, as it can really disrupt your travels. I just looked at what is called the "High Current, Low Voltage" schematic for our '06 Dynasty. The chassis charging system is extremely basic. It shows a single 4/0 red conductor from the positive terminal of the alternator directly to the positive terminal of the chassis battery. It also shows a single 4/0 black conductor from the ground terminal on the alternator to a probably nearby chassis ground stud. On our coach, and probably most coaches, the voltage regulator is contained within the alternator. To complete the charging circuit, it shows a single 4/0 black conductor directly from the negative terminal of the chassis battery to the ground terminal on the engine starter, and thence to the chassis ground, possibly through the frame of the starter, or thru a short cable to a very nearby stud. There are no switches or disconnects in that circuit, so it should not be too difficult to verify the integrity of that current path, aside from needing to be a contortionist and acrobat to maybe get to some of those connections, if you need to.

The first thing I would try would be to put a voltmeter on your chassis battery and read the resting voltage. It should be somewhat more than 12 volts. Hopefully it will be closer to 12.6 volts. A completely discharged battery will be 11.5 volts, or less. That will help to give you an idea of to what level your battery is currently charged.

Next, I would start the engine, and then read the voltage across the chassis battery, again. It should be well over 13 volts, and could even be as high as 14 volts or more. If the voltage is in the range of 13 volts to 14.5 volts, your battery is receiving adequate charging energy, and all should actually be good with that system. If it is still reading in the same range as it was with the engine not running, then you will want to determine if the desired charging voltage is available at the alternator's positive terminal with the engine running.

Extreme care is necessary to avoid injury from the fan belt or pulleys when you are working around a running engine. But if you can get to the positive terminal on the alternator with your voltmeter, with the engine running, check to see if it is in the 12 to 12.5 volt range, or in the 13 to 14.5 volt range between that positive terminal and ground. If it is in the lower range, the alternator is most likely in trouble. (Do make sure the cable and connections from the alternator ground terminal to the engine/chassis ground is good and solid.) If it is in the higher range at the alternator with the voltage at the battery still in the lower range, then the cable, or more likely one of the connections, at the alternator or at the battery is in trouble.

The proper operation of the Big Boy or other device constitutes an inconvenience, but failure of the chassis battery charging capabilities will quickly result in disruptions to your travel plans.

Let us know how you do. (I probably made a few errors here, but my fingers don't always listen to my head, so I apologize in advance.)

K7JV · 06-02-2019, 08:17 AM

That is a pretty cool document, YC1, thank you for sharing that. I like it!

ArkansasRomr · 06-02-2019, 05:01 PM

Good stuff Jim

I didn’t realize the leads went from the alternator to the chassis batteries. That’s pretty much what the old style cars do before the pc took control of everything. Which is basically what you said. It could be something as simple as corrosion on the alternator leads. I haven’t even looked at the alternator yet. Next on my list.
Thanks guys and I certainly will update you all on the discovery.