What is this and what does it do, Why would it be smoking. Getting ready to take a trip smelled something and found this smoking. The wire to the left was the one. I also had the docking lights on a good while don't know if that may have had anything to do with it and should i be concerned Thanks
That is your battery isolator. If it is smoking it surly needs replacing or upgrading to a voltage sensing relay. If you are in a bind you can tie the center wire from the alternator to the engine battery side and continue on. The house side you can leave the cable unhooked and wrapped with tape to keep from getting into trouble and charge the house batteries with the inverter/converter till proper repairs can be done.
Mike
Battery isolator. Ties charging system to both house and chassis batteries.
Clean up all connections and consider buying new isolator.
Here is a link to 3 and 4 stud battery isolator schematics much like the one you have. If you are in a hurry, you can just buy another, clean up the cable terminal ends and away you go. https://duckduckgo.com/?q=three+stud+battery+isolator+schematic&iax=images&ia=images&iai=https%3A%2F%2Fi.pinimg.com%2Foriginals%2Ffc%2F33%2F34%2Ffc33346192426fb2f9802d998cb67af3.png
There are more efficient ways today. Lots of articles on each way with the advantages and any changes you may need to the alternator.
Older OEM dock lighs use a ton of juice and could be associated with your cable smoking if there is any corrosion. Corrosion can be linked to high resistance and heat. If you have the older dock lights, change to LEDs as they use a fraction of the wattage.
Pierce
If you DIY, take close up photos with the cables labled (new lable if you can't read the OEM lable on the cables) Many people don't remember how they were installed and put the cables on the wrong terminal/stud. Our PO did that and had me wondering why both battery banks went dead at a wedding. Use a flat file to clean both sides of each cable end.
Pierce
Thanks for all the help.As for tying the wires together which one would the center wire connect to. Getting in to big of hurry not thinking right which comes easy for me.
The center cable is from the alternator. They should all have ID near the end of each cable but sometime hard to read because of fading/age. Don't know your model but our forum has the schematic so you can compare cables to what you see on the schematic Easy to take the schematic to a print shop and make a big copy so it's easy to read. So, here is a simple schematic on a three lug isolator with the cable from the alternator going to the center stud.
(https://www.infinitybox.com/wp-content/uploads/2021/02/battisoschematic-600x309.jpg)
Take the time to put all of your info, year, model, etc. like others have below the name and photo. It makes it much easier to help you in the future.
Pierce
Thanks so much. Going to clean the connections and try to make it where we're going. Try to figure and an isolator and replace it. The motorhome is a 98 u295 I will update in profile later.Big Thanks again to all and Happy Thanksgiving
Disconnect both banks of batteries before you do the isolator. Lots of amps there.
P
Welcome to the forum, it is really helpful if you fill in your signature with motorhome info, then everyone reading your post knows what your rig is, they are not all the same.
Good luck repairing your wiring issue.
Short term "fix":
Carefully label all wires so you can correctly install them on the new battery isolator. Or, as already mentioned, replace it with a more modern or KISS (they are different) battery isolator.
Combine ALL wires on one (any one) lug. Safest to disconnect both battery cables at the battery unless you are REALLY careful, as you don't want to "arc weld" anything.
Now the alternator and both battery banks are connected all the time. So, both banks will receive full/regular charge.
But, that leaves the batteries connected when the engine is not running as well. If on shore power, no worries, your converter or charger will keep all batteries charged.
But, if not on shore power it could discharge all batteries. So, if dry camping, disconnect the cable that goes to the HOUSE battery.
The battery isolator smoking is a sign that it is being overloaded, not that it is the failure component. If that is the case then simply tying the batteries together will move the next smoking component to be the alternator. You need to find the source of the overload. A high possibility is that a battery has a shorted cell. Also, keep in mind that there is a "sense" connection on that set up that is sensing the chassis battery voltage. That needs to be maintained. You need some serious diagnostics before just doing a quick fix.
Will it be safe to go on my trip and try to fix it when i get there. Was getting ready to leave this morning
I would say NO, based on your picture.
To get you down the road I would disconnect wire on left, tape up and make sure it will not make contact with any thing.
Then remove the center and 3 right wires, then get a bolt and nut to connect together. Tape up and make sure ends with not make contact with anything. While doing this make sure that the wires don't make contact with anything or you are going to see sparks fly.
Yes, two things can cause overheating-- overloaded as you mention.
But, the other is excessive internal resistance in the isolator, that can cause the overheat issue as well (read that "failed component").
Yes, it is possible for the isolator to fail in that way, but again that would most likely be due to overloading at some point. Usually, they fail open, a battery bank does not charge, or they get shorted and no longer provide isolation. Batteries can fail in many ways. System mods can also put stress on components. Things happen. My suggestion is that some real diagnostics be performed before a work around that can just move the problem to additional components. Worse would be the need for the fire extinguisher.
Good idea.
If looking for a significant overload/short, start by disconnecting (one at a time) the cable from isolator to each battery bank. AND disconnect the positive at each battery bank. Use an OHM meter to check for any continuity from the now-disconnected cable and ground (at battery end, end of disconnected cable to negative terminal of the battery. No question, if a positive cable has, for example rubbed through the insulation and is touching any coach metal it would cause a short.
Also, look closely at the batteries. Look for any swelling. If wet cell, check water level and use a battery hydrometer (under $15 at any auto parts house) to check Specific Gravity of the cells.
Clamp on DC ammeters are now reasonably priced and readily available. Let's you do some testing on the individual batteries for discharge or charging. On a periodic basis, it is a good idea to separate all the parallel batteries and do a capacity test on each one separately. Need a load bank or some creativity to come up with a plan. At the least those high amp quack battery testers will find the really bad ones.
Those docking lights eat up a lot of juice
Well made my trip and better yet made it back. While looking through post trying to decide on a isolator came across one about alternators. So i checked mine out and don't believe i have the right one and the wiring doesn't look right. Here's a quick pic i took try to get something better later
You are correct that isn't the OEM alternator for your age/model coach. In your looking around search DUVAC system lots of info here on that subject. This happens a lot when a shop don't understand what alternator is need for a Foretravel.
Mike
As Mike says, that alternator is incorrect for use with a DUVAC charging system (dual battery bank and diode based isolator). The diagram posted by Pierce in Reply #6 will not work with that alternator. In fact, if your alternator was to be connected like that diagram, it probably wouldn't even turn on.
There are different ways to correct your setup, depending on what you want to do.
If you want to restore your coach to original factory configuration, it will require at least a new (correct model) alternator, and possibly a new isolator. Plus, your charging system wiring would have to be thoroughly checked and restored to OEM.
If you wish to keep the alternator you have, it can be made to work. It would require replacing your factory isolator with a DVSR (Digital Voltage Sensing Relay) of some kind, plus some changes to your charging system wiring.
Up to you how you want to procede.