Bounder: Mysterious wiring of F73-1020 BCC in Bounder

[Michael Oro]

As I am troubleshooting the various problems in my 2002 Fleetwood Bounder BCC (which is F73-1020 made by RV Custom Products) I am seeing things I cannot explain.

If you look at the attached picture, you will notice two wires that connect Aux Start Switch and Ignition Switch wires to the Interconnect Relay control pin. These wires were clamped on top of the existing wires, so I assume they were added later. They also effectively interconnect pins #10 and #11, so the aux start switch and ignition switch are now wired "in parallel".

According to the manual and schematics (see second picture), they bypass the Interconnect Relay Driver (BIRD) that implements a 15 second delay before engaging and disengaging the Interconnect Relay. The only conclusion I can draw from this is that the BIRD was fried and this was a cheap way to "fix" it. What it does, basically, is engages the relay by the Aux Start directly and also engages it when Ignition Switch is on. But in this scenario, Aux Switch becomes irrelevant as it would always interconnect the batteries on ignition. And yet I remember distinctly that when I could not start the RV because of the drained Chassis battery, I was able to start it by pressing the Aux Start switch.

Any other ideas?

[Vato]

Originally Posted by Michael Oro

As I am troubleshooting the various problems in my 2002 Fleetwood Bounder BCC (which is F73-1020 made by RV Custom Products) I am seeing things I cannot explain.


Any other ideas?

Contact RV Custom Products.... I had an issue last year and John was very helpful over the phone

[SavnTheWales]

Maybe this is related. I asked RV Custom Products about moving the Lithium batteries. They sent this reply.

“A potential problem with charging LiFePO4 batteries from your engine alternator is the requirement that charging current be limited to 0.5C (capacity). Our interconnect relay merely parallels coach and chassis batteries and provides not current limiting, if needed. Also, a relay provides no protection of an overcurrent condition on your engine alternator.

We recommend you defeat our voltage control of the interconnect relay. Do this by removing the yellow wire from the coil terminal of the interconnect relay. Provide charging of your lithium batteries from the engine alternator by using a DC to DC converter or Battery Isolation Manager. If you wish to retain the aux start feature of the interconnect relay, snip the wire going to P4-10 and wire it to the coil terminal from which you removed the yellow wire”

[Michael Oro]

Originally Posted by SavnTheWales

Maybe this is related. I asked RV Custom Products about moving the Lithium batteries. They sent this reply.

“A potential problem with charging LiFePO4 batteries from your engine alternator is the requirement that charging current be limited to 0.5C (capacity). Our interconnect relay merely parallels coach and chassis batteries and provides not current limiting, if needed. Also, a relay provides no protection of an overcurrent condition on your engine alternator.

We recommend you defeat our voltage control of the interconnect relay. Do this by removing the yellow wire from the coil terminal of the interconnect relay. Provide charging of your lithium batteries from the engine alternator by using a DC to DC converter or Battery Isolation Manager. If you wish to retain the aux start feature of the interconnect relay, snip the wire going to P4-10 and wire it to the coil terminal from which you removed the yellow wire”

Well, this semi-explains why the P4-10 is wired directly, although the yellow wire is also connected still. And I don't have Lithium Ion batteries. So my assumption is that the BIRD is fried altogether.

And it still doesn't explain why Ignition Switch is also wired directly to the ISO relay. Does it get energized when the switch is turned to ACC position or when it is turned all the way to start the engine?

While on this topic, maybe there is a more modern replacement for this BCC, which provides better control over the charging and switching of the batteries? Something that may even (gasp) report the current state of charge and battery condition to the cabin dashboard?

[computerguy]

No replacement that I have heard of and I am pretty active on here. This forum is probably your best source of info too.
They do make different revisions which simply change some minor things like at what voltage the 2 battery bank system connect and disconnect.

There is some functionality in Fleetwood products (at least in my '16 Bounder) to show the bank voltages on the system display. This is the one that shows the tank levels, genset hours and battery voltages. Mine is over the entrance door. But that is all that I know of. But a DIYer might be able to tie into that or simply add their own voltage meter. I can display voltages of the house batts via the Magnum Mag-Web and connect via any browser. The engine voltages I display via an OBDII connector and Torque with a computer on my dash.

[House Husband]

You probably need a new circuit board. And then wire back to OEM.
The logic in the circuit board closes the isolation relay when either battery bank reaches 13.3 volts and opens the relay when either battery bank reaches 12.8 volts.
The RV Custom products system is usually very solid.
The one on my 95 Bounder, still functions as designed.
Note the Rev. # in the circuit board and replace with the same or higher.
EBay & Amazon some times have such items.

Richard

[Michael Oro]

I took a short trip on the RV after I replaced the Isolation relay and installed the LED indicator in the cabin showing the connection state of the relay. It behaved as expected around 12.8 (iso relay opened) and 13.2 (iso relay closed) volts. It was interconnected while I was driving and batteries were being topped-off by the alternator. I was boondocking, so at some point the connection was dropped, thus saving the chassis battery (supposedly). But something "interesting" happened in the morning. The steps and jacks stopped working. Evidently, they are operating from the chassis battery. As I measured voltage on the battery, it was 12.2 volts. But when I measured the voltage for the steps after*the fuse in the BCC, it was only 10.1 volts. Is there something in the BCC that can cause such drop? It could mean that my chassis battery can't hold the charge and needs to be replaced, but at the same time I was able to start the engine from it without a*problem. Can it be "depleted" to the point it cannot operate the stairs and yet have enough cranking amps to start the engine?


I was able to operate the steps and the jacks by pressing Aux Start. It connected the coach batteries immediately and gave me about 15 seconds until the relay opened automatically. That's how I operated it for the rest of the trip. During driving it never got to "interconnect" and charge the coach batteries even though it was showing 13.6-13.8 volts on the sockets while the engine was running. As I got home and connected to the shore power, the interconnect happened immediately. So it seems that the alternator is not producing enough current to charge both batteries when the chassis battery is "depleted". Again, I put "depleted" in quotes because it was cranking the engine just fine, without Aux Start interconnection. But the stairs and jacks would appear dead at the same time. Even when the engine is running!