Where is Battery Isolator Controller?

[thorapy]

Apparently as we driverour 2014 Thor Citation / 2013 Sprinter RV our house batteries are not charging. Has anyone experienced this? Is there a "on/off" switch on the Battery Isolator Controller or a fuse that should be checked?... I have no idea where the Battery Isolator Controller is... any help appreciated. ..thank you.

[steelerr]

On my 2005 Four Winds, the battery isolator solenoid is located under a panel, behind the charger/fuse panel. This despite the Owner's Manual stating it is underneath the hood.

[FW28z]

If your house battery does not charge via engine alternator, you may not have an isolator.

One of my future projects is to figure out my DC system.

[blw2]

Originally Posted by FW28z

One of my future projects is to figure out my DC system.

I think you and me are on a very similar trajectory!

On this topic, i'm starting to wonder if anyone has figured out a gauge or a idiot light to indicate that the charge system is working.
With no schematics or usable info from the manufacturer, and with all of these relays and such burried, it seems that most of us don't know how these things work.... and even if we did there is no good way short of killling your battery to know if the isolator or relay has failed!

[FW28z]

Well I am now officially confused.

I got curious and looked under the hood of my E450. I found two wires on the battery, one going into the innards of the engine compartment (which I assume is the factory connection), and the other going over to the driver's side firewall and connected to a Trombetta 694-1251-012 contactor.

I was able to find a spec sheet on the contactor and I did not see anywhere where there was a battery isolator or combiner function.

This contactor is for coupling the house batteries to the engine battery when the engine cannot start.

However, I am certain that the batteries charged fully after running them down to 75% one time and then driving about 3 hours. The only thing I can fathom is that the contactor closes when the engine is running... which would charge the house battery. But what connection from the engine signals the contactor to close is a mystery.

I do have an electrical "up-fitter" drawing from Ford for the E-450. I am going to check and see if there is any kind of engine running lead that is available.

I hate this reverse engineering stuff... but it is the only way to figure out this stuff.

And I figured that even if Thor had a schematic, my current experience tells me it would probably be wrong anyway.

[FW28z]

Well I did find that there is a Run/Start wire for the E450 - so perhaps the solenoid is connected to it. I need to put a voltmeter on the contactor - start the engine, and see what happens.

http://thebigfootleveler.com/uploads..._Schematic.pdf

If indeed this contactor closes with the engine running, it would not surprise me as this would be the "cheap" way to do it.

[blw2]

yeah, the cheap way would have been my guess.....

[FW28z]

The proper way would be to update the solenoid with something like this:

http://www.bluesea.com/products/7622/ML-ACR_Automatic_Charging_Relay_with_Manual_Control_-_12V_DC_500A

[blw2]

exactly!
Imagine that.... even an LED output to indicate state.

I know that mine is a low end motorhome, but still.....it costs as much as my 1st two houses did! Seems like it should have basics like this. I don't need ultra high end but I like things done right.

[FW28z]

OK, I did some checking today and confirmed that the engine emergency start solenoid (which connects the house to the engine batterys) does indeed close when the ignition is in the run position - which connects the house and engine batteries together when the engine is (hopefully) running.

Therefore, the house batteries are charged by the engine alternator (or engine battery if the ignition is left on without the engine running). This is slightly disadvantageous vs. a true combiner as a combiner would disconnect when the engine quits running, but in a practical matter, how many times would the engine be off but the ignition in the on position?

I confirmed it by touching the solenoid inside the engine compartment when my wife (trusting soul that I am) put the ignition switch into the "Run" position.

Here is a reversed engineered schematic. It may not have all of the components - especially the diodes I show. Call them "virtual diodes" for now as there should be some isolation between the run switch voltage and the emergency start switch. Not saying there is - seeing as how cheap things are done on the RV - but there should be.

I have not found the part number yet for the house battery disconnect contactor, but I would not be surprised if it were not the same one as used in the engine compartment.

[blw2]

Nicely done, FW28z!

It seems like their startegy violates what I learned in "Battery Bank 101".... that battery banks should be made up of like batteries of the same condition and vintage.

I suppose not a big deal while either one of the two charging sysems are active
but if that one relay fails you have a bank now made up of a deep cycle battery and a starting battery
each of which might be a differing state of charge
and each of which have a different prefered charging profile.

And a problem.....
Every time you start the chassis engine, the starter motor is pulling from both battery systems.... a problem it seems, if you have true deep cycles for house batteries....

and then something I don't understand.... what happens to the batteries when both the alternator and the converter are trying to charge at the same time?

[FW28z]

Well I got a drawing from Thor this morning, and my reverse engineering was close, but not accurate. I need to state first that the design is better than I first imagined. But I did not look in every nook and cranny, so that is where I left one important component out.



If you notice, there is the addition of an Intellitec 00-00629-120, which is called a Isolator Relay Delay Module. In fact though, it is a voltage controlled relay. After downloading the spec sheet, it will only energize when it sees alternator voltage, and only after an appropriate delay period.

So in effect, the combination of the Intellitec module and the Trombetto contactor create a true combiner.

What is different though about the Intellitec module is it has a time delay that prevents the contactor from closing until it sees the alternator voltage for a few seconds. This allows the engine to initially start without having the load of producing current from the alternator to charge the house batteries.

I was able to confirm this delay by watching a voltmeter connected to my house batteries, and sure enough, the engine was running for a few seconds prior to seeing the alternator voltage on the house batteries.


One thing though that has me confused (and I marked the drawing with ???), I am not sure that makes any sense to have that wire there. I am now wondering if it is there or if the drawing is a mistake.

[FW28z]

One thing has me a bit confused. I verified that the contactor closed when the ignition was put into the run position without the engine starting.

However, I also saw that by placing a voltmeter on the house battery, that there was a 3 or 4 second delay in the house batteries seeing the charge voltage.

The only thing then to me that makes sense is the contactor closes on the RUN position, but opens again when starting the engine until the isolator closes it again.

On the other hand, the data for the isolator states that the isolator opens the relay when the engine battery voltage drops below 12V. This means a fully charged battery might close the contactor, but a less than fully charged engine battery will not close it.

[blw2]

Originally Posted by FW28z

.......On the other hand, the data for the isolator states that the isolator opens the relay when the engine battery voltage drops below 12V. This means a fully charged battery might close the contactor, but a less than fully charged engine battery will not close it.

if I'm understanding you correctly.....
Seems to me that this would be a safety so that if the chassis engine battery is low, full output form the alternator will be available to charge it, taking priority over low house batteries.

also, I suspect that the ??? line is in error. I agree with you.... doesn't make sense....
This is where the house disconnect relay would be wired, so maybe it was drawn poorly so as to be confusing.

As I've written before, I have tried on multiple occasions to get a schematic out of Thor, with no luck. You must be living right!

[FW28z]

Send me a PM with your email address and I can send you the schematic. It is a PDF.

[MattMcPherren]

Originally Posted by steelerr

On my 2005 Four Winds, the battery isolator solenoid is located under a panel, behind the charger/fuse panel. This despite the Owner's Manual stating it is underneath the hood.

Help please! I have a 2003 Four Winds Five Thousand. Trying to find the battery isolator solenoid under the bed and behind the fuse panel, as described elsewhere in this thread. Can't seem to find it, and can't hear it click. Can anybody tell me what it looks like, and exactly where it is? Where is the panel that's referred to? Do you mean the front panel of the 12 volt fuse box? Or is it somehow attached to the back of the fuse box? Or is it elsewhere under the bed, but not inside or on the fuse box? I'm totally bewildered.

[Tlwalton]

I have been having issues with my isolation switch ever since I replaced the coach batteries. We have a Freedom Elite 28U and our switch does not “click” when we try and connect the coach to batteries. I pulled all panels and traced the switch wiring and coach batteries. I found that both positive leads from the coach batteries run to a terminal behind my breaker panel under the oven. One terminal had voltage and the other one did not. The attached picture shows the terminal. There is a black reset button on the side of the terminal. Press this to reset the terminal and all is well. Been looking for this answer for 2.5 years. Hope this helps!!!

[Tlwalton]

Sorry the picture is upside down!!!

[MikeAdkins]

I have a 2018 Thor Quantum and isolator relay is in engine compartment under the radiator overflow... mine is bad right now... engine won’t start and house bats dead.....

[Jspear]

Does anyone have any idea where the isolator/trombetto/contactor would be on a 2015 Ace 30.2 model? I have located the BIRD, but can't locate the trombetto to troubleshoot why my house batteries arent charging off the alternator. Thanks in advance!