I had started a thread asking where to find the BIRD on my ME...after weeks now of poking and searching, followed by hours of researching iRV2 forums (and others), I decided to start a new thread with what I found in hopes that others who are either troubleshooting their BIRD, considering upgrading their system, or thinking about adding a battery system could leverage my efforts. Just note, the conclusions are my opinion and might be worth what you paid for them
I have an ME, and from what I gather, it was the first one TS built. It was the demo model (has the Harley-Davidson orange) and came with lots of bells and whistles that were state of the art in 2005 when it was being built, like remote tire pressure monitoring and a radar-based, collision avoidance system. What it didn't come with, aside from the standard leveling system with a normal hydraulic pump (see my other thread on that challenge) nor documentation worth using to troubleshoot systems, was a battery isolation management system. I discovered this, like many have, when I noticed my chassis batteries did not charge when plugged into shore power or with the genset running--only charged with the motor running (or by the battery tender I installed as a remedy). While I DO have a Battery Boost that lets me tie the chassis and coach batteries for starting, that is a simple solenoid tied to a switch on the panel in the coach. Having traced every battery wire/lead throughout, under, in and out of every nook and cranny, I now confidently conclude TS didn't see fit to give this ME the BIRD (so to speak).
Having concluded I lacked a BIRD, I first purchased a BIRD-Diesel 2 Controller from a wholesaler who had several overstocked items, then downloaded the service manual and data sheet from Intellitec (very helpful people, I might add). I intended to wire it to the existing battery boost solenoid, but noted that the diagram in their manual (first picture) called out a very specific (and expensive) solenoid, the Big Boy, to do the high-amp connection. I knew there were different types of solenoids and that my existing one was clearly capable of 200amps (according to the lable). So my first objective was to see if that Big Boy was a 'nice to have' or a 'required to have' item.
For the next several days, I went digging on this forum and others for information on the Big Boy to see if a suitable substitute (or source) existed since on the surface, it didn't seem to be that unique. As I'd seen with other items, manufacturers often repurpose items commonly made for other vehicles, stick a new label on them, and charge significantly more (the step motor for my last RV was the passenger side power window motor from a Ford, as I recall). In the case of the Big Boy, after all the research, I'm not certain you can use a 'similar' solenoid and don't think it's worth the risk. Here's why.
Let's start by looking at the types of solenoids that exist in this 200+ amp range. You will hear these devices called many different names, solenoid, relay and contactor being the most common. What's the difference? A relay has a common that is normally connected to one pole, and connects to another when the relay is energized. That's why the connections are referred to as normally open and normally closed. A contactor joins two poles (or multiple sets of poles) together when energized; and those poles are disconnected when not energized. Contactors are normally rated for higher voltages/amps compared to relays. Solenoids have a mechanical plunger that moves when energized, thereby connecting the two contacts. In this manner, it is essentially a contactor. That plunger can also move other things, like the gearing on a starter, which is why you'll find them on the outside of the starter motor for large motors, especially diesels. For the purpose of this discussion, though, I will just use the term solenoid, since that is what the Big Boy started out as before Intellitec repurposed it (more on that, later).
There are two general types of solenoids and this difference is CRITICAL when considering one to use in a battery isolation system: CONTINUOUS DUTY and INTERMITTENT DUTY. The continuous duty can be 'activated' (power applied to the coil that moves the plunger) continuously; as long as current is applied to the coil, the contacts remain closed. Intermittent duty can only be activated for a short period of time; exceeding that time results in the coil overheating and failing. Starter motor solenoids are almost always intermittent duty which is why there are limits to how long and often you can turn over a motor via the starter before risking damage to the starter, solenoid or both. On the other hand, continuous duty solenoids require a continuous flow of current to keep the contacts closed; and for large solenoids, this can be several amps. Hence, they are a bit inefficient to keep closed over long periods, and that current represents lost energy for a battery system.
To overcome this efficiency issue, engineers designed the magnetic latching solenoid. The original device used a small magnetic pivoting post within the top of the solenoid to hold the plunger in the closed position after the activation current was applied; and a magnet at the bottom that would attract the plunger depending on how current flowed through the coil. When current is applied one way, the pivoting post at the top swings to hold the plunger 'down' and the contacts connected. That let you remove current and the contacts (hi-amp posts) remained closed. To open the contacts, you reverse the current to the activation coil via a double-pole-double-throw switch. That caused the plunger to be attracted to a permanent magnet at the bottom, pulling it slightly closed and away from the top pivoting magnet. The reverse current repels the pivoting magnet so it swings clear such that when the current stops, the plunger pops up breaking the contact connection. In short, apply current to the coil one way, and the solenoid closes; reverse the current to the coil and it opens. Google US Patent 4,628,289 if you want to see this diagram and how it works. The advantage here, then, is that you don't waste current keeping the coil energized in order to keep the contacts closed. The Trombetta's isolation relay uses a magnetic solenoid/relay which is why it is more efficient (see picture) than a continuous duty solenoid or even the Big Boy.
WHAT IS THE BIG BOY SOLENOID
In my research on this forum, I found MANY posts, most with good info and some with not-so-good. Some said the Big Boy was a magnetic solenoid, which seemed to match the comment on Intellitec's data sheet. That sheet states that their solenoids are covered by US Patent 4,628,289...and that is a patent for a magnetic latching relay (solenoid). Yet the multiple references to the Big Boy 'humming' or buzzing when working didn't match any mag-solenoid/relay of which I was aware. Moreover, there was only one wire between the BIRD-2 and the Big Boy; and to reverse polarity on the coil, the BIRD-2 control wire would need to provide both positive AND negative voltage on the single wire. While that is possible, it's way easier to run two wires than do the stepping and transformers for pos/neg voltage. And, there was a comment in the spec sheet that the Big Boy is not a continuous duty solenoid and "requires an Intellitec Isolator - diesel controller to prevent it from overheating when it is used for continuous duty."
Not being able to sort this on my own, I called Intellitec and spoke to Shawn. He explained that the Big Boy "started out life as a diesel starter motor solenoid." That is apparent from the pictures. Compare the Big Boy to a diesel starter solenoid. The Big Boy base has the rounded-triangle mounting that matches many Delco and other starter solenoids, just without the plunger that engages the starter mechanics (see pics). Intellitec took the original starter solenoid and likely (their patent and trade secrets) had it manufactured to specifically work with the BIRD-2 Controller. The controller monitors voltage on both battery systems. When it sees that one or the other is receiving a charge (voltage above a certain level), it energizes the control wire causing the Big Boy contacts to close. When voltage is too low on one or the other system, it opens the contacts to keep one from draining the other unless it knows that other system is being charged. It has other logic to run the system to include logic for when both systems are receiving a charge. Importantly, since it is an intermittent solenoid, it energizes the coil via 'pulsing' of the control wire and not via a continuous 12V signal on the control wire.
WHAT IS PULSING?
The Big Boy is an intermittent duty solenoid, which means it cannot withstand a continuous current to the coil. Further, per the spec sheet, the actuation current is 6A; so keeping it energized would be a fairly significant drain on your battery system. To get around these issues, the BIRD controller initially hits the Big Boy coil with a full 12-volt/6-amp (needs at least 9V to actuate it) signal. It then begins to pulse that control voltage so it cycles between 0V and repeatedly lower voltages (a decreasing square wave) effectively pulsing the internal plunger open/closed. This is where the engineering by Intellitec likely makes the Big Boy different internally than the original starter motor solenoid. Somehow, either from latency of movement of the plunger and/or changes to the springs on the inside, the contacts remain closed even though the activation coil is being pulsed instead of receiving a steady energizing current. This pulsing gets them around the possibility of burning out the coil by continuous power application and reduces the amount of current required to keep the contacts closed making it more efficient.
This pulsing is the reason a Big Boy will 'hum' or 'buzz' when it is operating. It is also why, unlike a normal solenoid (not a magnetic one) you cannot simply measure the DC voltage on the Big Boy activation wire to see if it is working. That is like trying to measure the DC voltage of an AC doorbell transformer...depending on the voltmeter (even if it is a FLUKE), you'll get varying readings or none at all. To measure it correctly, you need an oscilloscope or other device to see the modulating square wave signal on the control wire. You could check it for DC voltage when the Start Assist is activated (that is a continuous 12V command), though. If looking to see if the BIRD-2 is working, you need a bit more to actually 'see' the signal than a standard DVM or analog voltmeter.
I'll be digging into my power bin this weekend installing the Big Boy in place of the existing Battery Assist relay. Since the activation wire for that passes through the home-run DC bin up front, which also has existing wires with both the ignition signal and genset on signals, I'll put the BIRD-2 up there and tie it in parallel with the wires from the existing Battery Assist switch on the driver's panel, above in the cabin. Hopefully will have a system where the house batteries charge while we drive rather than running the genset...and can take out the battery charger I've used to keep the chassis batteries charged while parked.