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Topic: "Separator" relay - connect/disconnect house battery

Posted By: vtraudt on 07/04/16 03:28pm

I need to properly wire up the separator relay that connect the house battery to the drive battery.

I have a switch on the dash that runs 12V from the house battery to the relay, closing the contact and connecting the house battery to the car battery in case the car battery is drained.

But with the engine running, the house battery should also be connected to the drive battery so it gets charged.

How is that done?

Posted By: RoyB on 07/04/16 03:50pm

I like the BLUE SEA SI-ACR Isolater idea for what I am doing here.. This is available from AMAZON...
google image

When engaged this smart relay monitors the CHARGE STATUS of the Start Battery and only switches in the HOUSE BATTERY when the truck alternator is putting out 12.75VDC or so... This prevents the HOUSE Battery from ever discharging the START Battery...

google image

Other brands doing the same thing are availabke also...

Roy Ken

Posted By: MEXICOWANDERER on 07/04/16 03:57pm

1. Forget switch

2. Forget switch

3. Forget swtich

Connect the ground terminal to chassis negative. Chassis battery to one post, house batteries to other post.

It's all automatic and correct. No wires to dash, no stupid switches. It connects and disconnects batteries correctly. On time, never forgets and never makes a mistake.


Posted By: YC 1 on 07/04/16 08:21pm

What year and model do you have. It may be as simple as a blown fuse that supplies the same thing as the switch you mentioned. It would be powered when the ignition is on.

H/R Endeavor 2008
2013 Ford Edge toad
Full Timers

Posted By: DrewE on 07/04/16 10:23pm

One common arrangement is to have the emergency start switch be a SPDT switch. The common contact goes to the relay control line. The normally closed contact (i.e. when the switch is not pushed in) goes to some ignition switched power source in the chassis. The normally open contact goes to a house 12V circuit. The same relay is used both for emergency starting and as the battery isolator. Obviously in this case that relay needs to be rated for continuous duty and also capable of handling a short duration high current.

Sometimes the two systems are completely separate, too, and another relay or solid state power diode used to permit charging the house battery from the engine alternator.

Posted By: MEXICOWANDERER on 07/05/16 12:07am

Mount a Ford starter solenoid above the battery charge divider. They are built to withstand 800 amperes for 15 seconds. wire the relay base to chassis negative. Run a wire to s dash switch then to chassis battery positive. A shorted field coil will almost instantly fry a charge divider solenoid. How about having a ten dollar Ford solenoid laugh at an armature or field short while the charge divider solenoid stands back and watches the show? This is an extremely easy modification and it works like a charm. Fuse the Ford relay/solenoid for a 15 amp draw (inrush).

Posted By: vtraudt on 07/05/16 05:41am

YC 1 wrote:

What year and model do you have. It may be as simple as a blown fuse that supplies the same thing as the switch you mentioned. It would be powered when the ignition is on.

1995 Fleetwood Tioga Montara 29ft Ford 350 Econoline Chassis 460 7.5 liter.

Posted By: vtraudt on 07/05/16 05:48am

vtraudt wrote:

I need to properly wire up the separator relay that connect the house battery to the drive battery.

I have a switch on the dash that runs 12V from the house battery to the relay, closing the contact and connecting the house battery to the car battery in case the car battery is drained.

But with the engine running, the house battery should also be connected to the drive battery so it gets charged.

How is that done?

Note: that switch did NOT work. I ran a separate wire from house battery to the switch to the separator solenoid. So now I can connect car and house battery manually.

But reading up on IRD and BIRD, and remembering 'funny' readings when checking the switch (at some point I THOUGHT I saw 12V at the switch, shorted the switch but could NOT measure 12V at the separator relay), I am not concerned that I do have a mystery device (IRD or BIRD). And by running a separate wire for the Emergency switch, I eliminated that device and now the house battery is only connected to car battery when E button is pushed; hence would not get charged during driving.

Anyone know where the IRD, or BIRD (or Ford/Fleetwood may call it BCC battery control center is located on the 1995 Tioga Montara 29ft Ford?

Posted By: vtraudt on 07/05/16 05:58am


Mount a Ford starter solenoid above the battery charge divider.

The separator solenoid itself works. Applying 12V to the coil clicks and closes the (normally open) relay.

What would an additional starter solenoid do?
Or are you saying:
a) use existing separator relay for manual switch to connect both batteries (drained car battery)
b) use 2nd Ford starter solenoid, run "key on" power to it. This will ensure that house and car battery are connected when engine is running (and both get charged).

Before doing any modifications, I would like to FIX what is there (or at least determine what is broken). Here: do I have a IRD or BIRD or BCC that is not working properly? Where is it located? Is that IRD or BIRD fused (maybe bad fuse)?

Posted By: MEXICOWANDERER on 07/05/16 11:23am

A solenoid/relay can click like a telegraph operator on steroids and the relay can be complete junk. It's the electrical contact points inside the relay, the ones that carry the current that fail, seldom the magnetics.

INTERMITTENT duty relays have much more power handling capability because their contact size is much larger, but even more importantly the magnetic force that slaps the contacts together is many many times stronger. A lot more amperage. A lot more heat build-up. When engaged too long the solenoid magnetic coil winding overheats then burns out.

I've seen too many shorted 10-MT Delco starters consume 500 amps + from a large chassis battery. This indeed and absolutely will burn the contact points of a constant duty solenoid. Older style big block Ford 460 starters can short and earlier DIESEL 6.9 failed starters taxed their solenoid. Power the solenoid coil and switch from the HOUSE battery not the chassis battery.

Mounted 6" apart, the paralleling wires can be of 6 AWG and they will work fine to jumper. I've done with 20MT Delco Diesel starter rigs and it works fine.

The bonus comes with much longer life for the constant duty solenoid that allows the chassis bank to charge the house bank. 800 amps is a lot of armor.

Posted By: Tom_M on 07/05/16 12:49pm

The BIRD is a delay module that connects to your isolator/separator solenoid. It delays connecting your coach batteries to your engine battery. In the event that your coach batteries are dead, it gives you enough time to start your engine before connecting the coach batteries.

Here's a diagram:

2005 Born Free 24RB
Towing 1978 VW Bug convertible
Minneapolis, MN

Posted By: road-runner on 07/05/16 01:08pm

The bird will give you all the time in the world to start the engine before connecting. It won't connect until after it sees charging voltage on the engine or coach battery.

2009 Fleetwood Icon

Posted By: vtraudt on 07/05/16 01:14pm

Where is the device (BIRD or IRC or else) located on the 1995 Fleetwood Montara 29FT Ford chassis?

Posted By: MEXICOWANDERER on 07/05/16 01:22pm

Looks like a diagram of a North Korean Scud ER missile.

The more solenoids, the more wires and connections involved the chance of trouble goes up by the square of the components. This is basic electrical engineering. The Blue Seas and Sure Power splitters operate on the same exact principle - allowing the starting battery to charge first. BI DIRECTIONAL means the allowing of house battery charging to automatically trigger the charge manager thus charge the chassis battery. It works in both directions. Except for a .250" faston terminal wire to chassis negative the entire setups are potted. Solid. But for safety's sake I recommend the 200-ampere model. Bi-Directional.

Posted By: Tom_M on 07/05/16 02:20pm

Only the ioslator relay is needed. The other two are battery disconnects. My coach has a BIRD and one isolator solenoid. The coach batteries have a single disconnect switch.

Posted By: MEXICOWANDERER on 07/05/16 03:46pm

1-2-both-off switch

Is obsolete?

Posted By: Tom_M on 07/06/16 09:37am


1-2-both-off switch

Is obsolete?
A switch is fine except when you forget to disconnect from the engine battery and drain all your batteries, leaving you stranded.

The OP has a BIRD type configuration and is trying to figure out why it doesn't work.

Posted By: MEXICOWANDERER on 07/06/16 11:27am

"when you forget to disconnect from the engine battery"

A dash switch is different? My recommendation is to suffer testing all those "BIRD" points with a meter (while holding a troubleshooting guide) to the maze of connections to find the problem.

Posted By: road-runner on 07/06/16 12:11pm

I've helped debug several Fleetwood/BIRD system failures and all of them have had one of the following causes:

1. The isolator relay has failed. Simple to check: (1) Plug into shore power, (2) Give the BIRD a couple of minutes to engage the isolator relay, (3) Verify nominal +12 at the isolator relay coil, (4) Measure the voltage drop across the isolator relay contacts, which shouldn't be more than a tenth or two.

2. The fuse between the chassis battery and isolator relay has blown. One way it blows is when one of the two batteries is seriously run down and the other is charged. When a charging source is applied to the already charged battery, the BIRD engages the isolator relay, a few hundred amps flow from the charged battery to the dead battery, and "pop" goes the fuse.

Anything is possible of course, but I've not seen any failures of the BIRD module itself. Where Fleetwood hid the fuse I'm referring to, or if it even exists in the OP's rig, I wouldn't know.

Posted By: vtraudt on 07/06/16 01:27pm

Still looking for the mystery device (BIRD or IRD).
Still hoping for tips where to even START the search (since no one seems to have a clue where Fleetwood puts them on a Tioga Ford chassis).

Not knowing what to look for (BIRR or IRD, how do they look) doesn't make it easier. ("Lets go searching. Don't know what to look for, and don't know where to search; but lets search anyways").

Probably take the car battery out again to see if something is buried down there (did see anything last time, but did not look for birds or other mystery thingis).

Posted By: vtraudt on 07/06/16 01:30pm

road-runner wrote:

BIRD engages the isolator relay

Does someone know if the 1995 Fleetwood Tioga on Ford chassis HAS A BIRD?
If so, which type/brand (so I can look up a photo of it to help searching for it).

Fuse: that would be a 'mega fuse' I presume to allow TONS of amp during normal operation.

Posted By: road-runner on 07/06/16 01:35pm

Here's a picture of a modern-day BIRD module

It's about 3 inches square and an inch or so high. In the installations I've seen the fuse is between 100 and 150 amps, so the power converter or alternator can never blow them, but one battery dumping into another can easily exceed that.

Posted By: Tom_M on 07/06/16 04:20pm


"when you forget to disconnect from the engine battery"

A dash switch is different? My recommendation is to suffer testing all those "BIRD" points with a meter (while holding a troubleshooting guide) to the maze of connections to find the problem.
A dash switch typically is different. It's usually a momentary switch that is pressed to jump the coach batteries to the engine battery in the event that the engine battery is dead. Once started you release the switch.

The diagram I posted is overly complicated because they included two battery disconnect solenoids.

Posted By: vtraudt on 07/07/16 05:59am

I checked the 6 inches high pile of documentation that came with the Fleetwood RV. Not ONE piece of paper really pertains to the coach (aside from an operator manual that mainly serves the legal purpose of container nothing but warnings).

I removed the battery AND the battery tray.

I crawled underneath the driver side kick panel.

I cannot find the mystery device.

That only leaves blindly testing the 10 or so wires (high school math indicates 3,628,800 variations). Any suggestions how to go about testing wires with respect to the mystery device?

One BIRD troubleshooting guide frequently refers to 'check on module' which is not possible without FINDING the module (or the wires leading to and from the module, or fuses).


The only thing I can think of: There are 2 wires that potential deal with a BIRD or other device:

a) one wire at the coil of the separator relay
b) 2 wires (one assume to be from a)) at the emergency start switch. Check continuity between 2 switch contacts and coil wire (to determine if and which wire is the emergency start signal wire)

Would testing voltage on those 2(3) wires for the following conditions (how much time should be allowed for the circuit to 'settle'?) help?

a) both battery connected, engine off, no shore power: nothing
b) engine running, no shore power: solenoid 12V, one line at switch 12V
c) shore power, engine off: solenoid 12V, one line at switch 12V
e) engine off, no shore power, shorten emergency switch (or 2nd person to press/hold switch): solenoid 12V

Posted By: MEXICOWANDERER on 07/07/16 07:04am

If a "normal" solenoid "clicks" with power applied and current running through it's internal coil to chassis negative...


Voltage at the two power posts with 5/16" copper threads...

Has different voltages present more than say .2 that's two-tenths of a volt

The solenoid is bad

What sayeth the readings?

Posted By: vtraudt on 07/07/16 07:28am


different voltages present more than say .2 that's two-tenths of a volt

The solenoid is bad

What sayeth the readings?

Solenoid clicks.
When closed, same voltage on both poles.

Posted By: YC 1 on 07/07/16 10:00am

Since you would like that device to activate two ways here is how to do it. You have already solve the one way buy running voltage through a simple switch as shown in one of the picture examples.

You now need for voltage to engage the device with the engine running. This is quite simple. Run a wire from the fused side or your dash radio fuse Or install an inline fuse and pick up power from your fuse block that is switched off with the ignition off. Then just run it to the side of the switch connected to the device. You now have an Either circuit. Either one will activate the device.

Yes I know turning the switch on with the engine off will send power back to the fuse panel but that can be solved easily with a diode inline with that line.

Posted By: road-runner on 07/07/16 10:23am

I'm still not 100% convinced you have a BIRD, but since you can hear the solenoid click, it's pretty easy to figure it out and troubleshoot the system. If neither of your batteries are heavily discharged, this is how it should work:

1. Apply shore power and turn coach battery switch on. The solenoid should click in about 30 to 60 seconds.

2. Verify again that the voltage on both sides of the solenoid is the same. Then check the engine battery voltage, which should within a tenth or two of the voltage at the solenoid (definitely over 13 volts). If the voltage at the engine battery is lower than at the solenoid, suspect the big fuse has blown.

2. Disconnect shore power. Wait for solenoid to disengage (on mine, turning off the coach battery switch forces this, otherwise it can take up to an hour). Start the engine. The solenoid should click in about 30 to 60 seconds.

Posted By: MEXICOWANDERER on 07/07/16 11:21am

After re-re-re-reading your posts, it may well be at present the switch is the only on/off control for the solenoid.

The ignition signal that makes the solenoid "automatically come on" with the engine running is called the IGNITION B signal. it is the same one that powers, wipers, heater blower, etc. The one where when you go to crank the engine, the signal is suppressed until the key is released. Do not use the IGNITION A circuit that stays on when the key is turned to "on".

I see ZERO VALUE in having a dashboard battery paralleling switch unless it is a momentary switch that powers an engine starting solenoid for boosting a low chassis battery. There is too much to forget and go wrong with a manual paralleling switch used for charging.

And as far as "THE BIRD" is concerned, one that the control is mounted one place and control wires run to distant solenoids is asking for headaches. It is the terminals that corrode and the vulnerable wiring that cause all the problems.

If I ever progress to the state of extreme laziness where I just cannot pull myself together enough to shut off the Cole Hersee battery switch, I'll hire a wet nurse and switch to a wheel chair. Ring down for room service, or eat out. Assume a "I have people who do that for me" attitude.

When I switch off the battery switch, I demand a I'll-stake-my-Life-On-It surety that those batteries are off, and not "maybe off".

Posted By: MrWizard on 07/07/16 01:53pm

to add to the confusion
Technically there is NO "battery separator relay"

the BIRD aka "Bidirectional relay control" is just a control board

the battery disconnect solenoid, is separate from the Charge 'Combiner relay/solenoid"

the chassis aka vehicle wiring and charging is different and separate from the HOUSE/RV wiring

the Combiner relay Or diode battery isolator, is there so the alternator will charge the house batteries while when the engine is running

the BIRD, IF one is there controls the combiner so that chassis can be kept charged even when parked

its a two way switch, which ever side is HOT and charging, gets charged first, and then the control closes the combiner relay to charge the other set

with the engine running the combiner will NOT be engaged until correct voltage level is reached at the chassis battery then it will engage the combiner to charge the house

so if both are low, the chassis is charged first, when the engine is running
this could take minutes or even an hour

it also does the same thing when parked, and plugged into shore power, but in reverse
the house must reach the charge setting, before it will engage the combiner relay and charge the engine/chassis battery
this is the main function of the bird, secondary function it saves the alternator, by keeping it from being over worked, LOW/DEAD house batteries will not come online until the engine/chassis batteries are charged

quite frankly, i think they are a royal pain and do not like that system

Radiate The Happy

Connected using Verizon and AT&T
1997 F53 Bounder 36s

Posted By: MEXICOWANDERER on 07/07/16 03:10pm

To IS or not to IS
That IS the question

IS there a control board

OR IS there NOT a control board?

Look, the word CONTROL means not-expected operation. Most bi-directional units have a threshold voltage. If this one solenoid switches on and off with the key what are the chances of having a control board fail in that particular mode?

I have seen a lot of rigs where the dual throw rocker switch, momentary one side was neutered and changed to IGNITION B because starter motor current inrush blew the solenoid contacts to East Jesus. When in the opposite position permanent on, the system did nothing, the switch just sat there are grinned at you. Pressed for "Emergency Start" that grin did not change. Not functional.

Control function is supposed to allow the chassis battery achieve 13.2 volts whereupon the SMART solenoid enables both banks in parallel.


When the HOUSE batteries achieve 13.2 volts, the solenoid will parallel both banks.

The engine alternator thusly ends up charging both house and chassis batteries

The converter or inverter ends up charging the chassis battery. 99.999% of Mopar ECU voltage regulator problems do not occur within the ECU. They occur at the wire termination of the field to ECU connection. I should know. I own one of the millions of misfits.

Alternator to external voltage regulator harnesses must be constructed near bulletproof and the regulator must not be contained in an ECU located right at the engine battery. MoPar chose to ignore this.

So an overwhelming majority of today's alternators are housed within the alternator to minimize a crappy quality but expensive harness to go bad. Stupidity to cure shoddy construction practices.

But BIRD units do not have to live in a 220F environment. They can be integrated into a tower type ESSEX solenoid. compared to the standard garbage metal solenoid the Essex is like comparing a Rolls Royce to a Ford Pinto.

Potting the entire works except for male faston terminals used for chassis ground makes the potted unit far less trouble prone. For mechanical strength I used 12 gauge wire, solder and glob of grease to make the chassis negative wire less vulnerable.

I then mounted that six dollar Ford starter solenoid above or below the Bi-Directional relay, and THAT wire ran to the dash switch.

I must have installed 40-50 units this way (Armando learned how to do this right and I supervised) and after insisting the 200-amp separator be used, I NEVER had one comeback in what? Ten? Eleven years? There is no strain on solenoids if they are not overtaxed for engine starting duty. Use the right component for the right job. An 800 ampere rated Ford solenoid can withstand tantrums from the most dysfunctional malfunctioning starter motor.

Yes, a person "could" reharness a functioning remote control type BIRD then use Essex type tower solenoid(s) and achieve a decent setup. But laying in a good length of critical grade chassis harness is not inexpensive nor quick. It involves using cross link XT wire, soldered connections and stout protection like nylon cable spiral wrap. And Adel type clamps to secure the entire harness to chassis tie points.

Why bother with all that when there are good units out there like the Blue Seas and Sure Power integrated sealed units? Even a cheapo online Ford starter solenoid works great for emergency jump starts but I would grind off the cad plating around one mounting hole and SOLDER the necessary ground wire running from the Ford solenoid mounting bracket through a quarter inch ring terminal, to a 12 gauge wire (again for mechanical strength then to a secure frame ground. Then a glop of chassis grease was slopped over the frame connection.

Silicone grease was applied to all exposed terminals, especially fast-on type. Terminals were tweaked to very firm push on effort then strain relieved with an adel clamp.

Do it once, do it right and go on to bigger and better things. To bad this cannot be done with converters and cranky electro-chemical sensitive batteries.
By connecting

Posted By: vtraudt on 07/07/16 04:49pm


dashboard battery paralleling switch unless it is a momentary switch that powers an engine starting solenoid for boosting a low chassis battery.

It is monetary switch. Press while turning the key to crank. Emergency only.

My house battery 'disconnect' is actually a 'dogbone' (turn key and remove = disconnect') with all the darn undocumented wiring Fleetwood THROWS into the coach (the word 'running wire' does NOT apply to their wiring method).

Posted By: vtraudt on 07/08/16 06:39am

All fuses I could find checked.
Put everything back together.
Don't know where the 2 purple wires for the separator relay should go.
One has continuity to the emergency switch, the other NOT.
None show 12V or ground with shore power plugged in or otherwise.
Separator relay is working when manually applying 12V to the one pin (not sure where ground comes from).

I will no try to check if battery is charging under shore power and engine running. Not sure how, but one test: measure battery voltage alone, and then with shore power on and also with engine running. If voltage shows notably higher, then some charging must occur.

If battery is charging: I will give up on finding/fixing the BIRD or IRD or else mystery device, will run house and car battery together and disconnect and isolate any wires to/from emergency switch and to/from separator relay.

Enough with this Fleetwood wiring and documentation nonsense.

Posted By: YC 1 on 07/08/16 10:35am

"One has continuity to the emergency switch, the other NOT"

See if there is voltage on the wire that has continuity to the switch when the engine is running.

I am 99% certain you do not have a BIRD. You most likely have a simple solenoid system. When connected to shoreline your engine batteries probably do NOT get charged. The solenoid you are working with is activated by the emergency switch of course but there is probably a parallel wire (perhaps purple), that supplies voltage to the same post on the solenoid when the engine is running. It may even work with the key in the on position and the engine not running.

The solenoid is grounded via its metal case if only one wire is needed to make it function. If you were testing things at any time and did not have it mounted you could get confused easily. Or if there is rust preventing it from contacting ground. In some cases one of the little posts is also connected to the solenoid housing for ease of supplying a ground.

It is NOT uncommon for earlier model RV's to not be setup to charge the engine batteries when on shoreline. Once you get this sorted we can offer many inexpensive devices to accomplish that task.

Posted By: MEXICOWANDERER on 07/08/16 02:51pm


This is a Ford type fender mounted starter relay. This is the one and only type of relay to use when paralleling battery banks to jump start the engine. It is referred to erroneously as a solenoid. Solenoids move something and they also may make electrical contact. One full-on jump start will crispy-critter a standard constant duty relay's contacts.

Be sure to run terminal and wire from either of the relay's mounting ears to a good chassis negative "ground". Otherwise it won't work.

Posted By: Tom_M on 07/08/16 03:23pm

The OP has a working isolator relay. He is trying to figure out how to wire it up. There's no need to add another starting relay.

If the battery cables are still connected to the isolator, all you have to do is find a wire that is hot only when the engine is running and connect that to the terminal on the isolator coil.

Posted By: YC 1 on 07/08/16 04:19pm

Send me a PM with your e-mail and I will send you a simple schematic. It is too much hassle to post pictures or pdf's on this ancient forum.

Posted By: vtraudt on 07/08/16 05:25pm

PM sent.

Posted By: YC 1 on 07/08/16 06:15pm

battery combiner

There are lots of options but this is a good one. I have been using this one on my 40ft diesel for several years.

This is in reference to the PM I sent you.

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