Electrical Curiousity

Moder2 · 10-04-2006, 12:27 PM

I am not having a problem per se, I mostly am wanting to become more familar with my coach.

On the electrical system, in the forward bay on the driver's side there is all the electrical stuff. Chassis pannel, a relay pannel, and some other 12volt circuit breakers. There is also two large relays or seloids on the firewall of the front of that bay. I believe the smaller of the two and one closest inboard is for the generator. I think the other has to do with the battery disconnect/boost switches but I am not certain.

My query comes because I was digging in there for another problem and may have stumbled across this if it is a problem or not I do not know. When I was diagnosing a power issuse with my awning I noticed the large relay was "Warm" not mmelting warm, but warrmer than I thought it should be. What does this relay do? The engine is off, and we are long term camping, so It must be somehting for the house batteries?

The other strange thing I found was I pulled the little square relay for the "Aux Bat boost" and the big relay clicked. I swtiched it out with another similar relay and it did the same thing.

Now, I haven't really dove into it at all partly because I do not know what it does, and am hoping for a detailed explaination from someone on here, and partly because I only had myself at the time, and couldn't tell if I heard clicking or not by hitting the batt boost switch or the battery disconnect switch.

When i do hit the battery disconnect switch, it does kill just about everyhting in the coach. A friend without the inverter on a 01 journey says his coach is still active, that it just shuts off the house batts, and if he has shore power, his converter will power his 12 volt stuff. Mine is not that way, Bat switch is off, the coach is more less dead.

Any insight will be helpful!

Thanks,

John

Moder2 · 10-04-2006, 12:27 PM

I am not having a problem per se, I mostly am wanting to become more familar with my coach.

On the electrical system, in the forward bay on the driver's side there is all the electrical stuff. Chassis pannel, a relay pannel, and some other 12volt circuit breakers. There is also two large relays or seloids on the firewall of the front of that bay. I believe the smaller of the two and one closest inboard is for the generator. I think the other has to do with the battery disconnect/boost switches but I am not certain.

My query comes because I was digging in there for another problem and may have stumbled across this if it is a problem or not I do not know. When I was diagnosing a power issuse with my awning I noticed the large relay was "Warm" not mmelting warm, but warrmer than I thought it should be. What does this relay do? The engine is off, and we are long term camping, so It must be somehting for the house batteries?

The other strange thing I found was I pulled the little square relay for the "Aux Bat boost" and the big relay clicked. I swtiched it out with another similar relay and it did the same thing.

Now, I haven't really dove into it at all partly because I do not know what it does, and am hoping for a detailed explaination from someone on here, and partly because I only had myself at the time, and couldn't tell if I heard clicking or not by hitting the batt boost switch or the battery disconnect switch.

When i do hit the battery disconnect switch, it does kill just about everyhting in the coach. A friend without the inverter on a 01 journey says his coach is still active, that it just shuts off the house batts, and if he has shore power, his converter will power his 12 volt stuff. Mine is not that way, Bat switch is off, the coach is more less dead.

Any insight will be helpful!

Thanks,

John

AFChap · 10-04-2006, 03:06 PM

John

I will be very interested in any answers you get. I also have noticed the very warm (almost all the time) relay/solenoid. AND, recently when we were living on battery power for several days with generator recharge morning and evening, I noticed I could hear the relay clicking (opening, then closing I presume) periodically while we were on battery power.

Moder2 · 10-05-2006, 04:18 AM

I have not noticed that yet. Hmm.

It does make me feel a bit better if yours does the same thing. I wish one of the guys who know for sure would speak up!

John

Joe-K · 10-05-2006, 06:00 AM

I don't know for sure, but I don't mind guessing at it

Reviewing the Ultimates Automotive Wiring and 12 Volt Body Wiring diagrams, it appears that you have a charge control module on your rigs. The module I'm familiar with is the Intellitec Bi-directional control box which I had on a previous rig.

The control is designed to monitor both the chassis and coach battery banks, recognize when either of them was being charged, then connect the banks together if there was sufficient voltage to charge both banks. The reason it was called bi-directional is that it would work both ways. The system recognized if the chassis or coach batteries were being charged and there was sufficient voltage to charge both banks.

The way the unit worked it sometimes gave the symptom of a slowly clicking relay when the charging current was not sufficient to keep the voltage high enough to charge both banks. In other words, when I connected to shore power, the chassis battery voltage came up to a certain level so the Intellitec connected the chassis batteries through the emergency start solenoid. This operation permitted the chassis batteries to charge while plugged in. However, if I had a load turned on inside the motorhome, the battery voltage on the coach batteries dropped as soon as the chassis battery bank was connected so the relay opened again. This raised the chassis battery voltage so after a couple second delay, the relay closed and the process repeated. This cycling could continue until the chassis battery took some charge so that it presented less of a current draw or some load inside the rig was reduced so the coach battery voltage didn't drop as much.

Just as when the converter did nto provide enough charging current, the Intellitec control also prevented coach battery charging when the vehicle alternator wasn't providing sufficient charging voltage to the chassis batteries. When turning on large amounts of chassis battery demands (headlights, blower motor, etc) at low idle engine speed, the Intellitec would disconnect the coach batteries from the the chassis batteries so the alternator did not have to charge them at the same time.

During normal operation though when connected to shore power, the Intellitec would normally keep the auxillary start solenoid energized which kept both battery banks connected and charged. The auxillary start solenoid should be rated for continuous duty to handle that operation, but will get warm being constantly turned on.

Joe-K · 10-05-2006, 06:03 AM

Oh yeah....a picture is worth a thousand words. Here's what the Intellitec device may look like. Also in italics is the company's discription which is better than my attempt at describing it previously.

Intellitec's Bi-Directional Isolator Relay Delay™ offers a new approach to charging batteries in an RV application. Unlike prior systems that only allowed charging the RV battery from the engine's alternator, the Bi-Directional Isolator Relay Delay™ charges both batteries when either one is being charged. When the coach is being driven, both batteries will be charged from the engine's alternator. When the coach is plugged into shore power, both batteries will be charged from the converter. If neither battery is being charged, the batteries are fully isolated. The controller also senses heavy loads on either battery to prevent the wrong battery from being inadvertently discharged.

AFChap · 10-05-2006, 07:34 AM

Yes, the bi-directional Intellitec relay on the opposite (rear) wall looks very similar to that pic. And the explanation does make sense. The item we are referring to as being very warm is likely the auxilliary start solenoid. The brand name appears to be Trombetta. ...and the clicking noise I hear seems to come from either the aux start solenoid, or maybe the very similar solenoid next to it. What I don't yet understand is why I would hear the periodic clicking when there is no charging power being applied. Everything I have read here & elsewhere seems to indicate the relay will close/open to protect one of the battery banks from excessive discharge. Why would that be going on when we are sitting calmly with maybe a light or two on with no incoming power? The chassis battery bank shouldn't be involved at that point with anything other than a few parasitic loads on the chassis side.

AFChap · 10-05-2006, 12:18 PM

Found a great diagram of the bidirectional relay & solenoids at Intellitec diagram. I think the very warm one is the one labeled "Isolator Relay" in the diagram. I don't know that I have a chassis disconnect.

Joe-K · 10-06-2006, 04:26 AM

That is a good document and diagram explaining the system. Our previous rig didn't have the chassis disconnect either, just the isolator and coach disconnect.

When my unit was doing that periodic clicking I spoke with Intellitec and they thought it was caused by the voltage difference between the two battiers being at just the right level that it caused the system to create the connection between the battery banks, then separate it again. It might have been caused by the differential requirement between the two battery banks being to small. Might be worth a phone call to Intellitect to explain it. I do recall they had some helpful people in technical service.

Moder2 · 10-08-2006, 05:25 PM

Thanks for the information guys, it is somewhat clearer, well about as clear as muddy water.

I do still have a couple questions for clarification.

If I am plugged into shore power, will the Aux Start switch have any effect? or will the selenoid be open?

If the Selenoid is open, why would the voltage on my one place have differnt voltages for both the House and Chassis Batteries? I am no electric genius, so please explain.

Thanks!

John

AFChap · 10-08-2006, 06:20 PM

I'll give it a shot...

If you are plugged into shore power, you shouldn't need the aux start as both banks should be charged. However, if your chassis batteries are bad and not holding a charge, then pressing the aux start will cause it to function as normal and tie both banks together so you can start the engine (or lower/raise your jacks and/or pull your slides in and/or extend/retract your entry step ...been there, done that ...all those things run off your chassis batteries ).

As to the One Place battery monitors, they aren't going to be truly accurate unless there is no charging going on. But yes, the two are not always identical on my coach either. I would guess that is because they (particularly the chassis batteries) are not always charging ...just as needed? Right now my chassis batts read 12.8 and house batts read 13.3. I believe that tells me the house batteries are charging right now, but the chassis batteries are not.

Anyone else truly know the answer??