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Old 04-30-2019, 02:50 AM   #5
Junior Member
Brand: Thor Motor Coach
Model: Vegas 25.2
State: British Columbia
Posts: 16
THOR #11108
Originally Posted by Oneilkeys View Post
Im not sure I understand your comment that the BIRD is wired directly to the Chassis battery. It is supposed to be wired to the ignition switch, so that the BIRD is only powered by the chassis battery when the ignition is on.

The following is from the BIRD instructions.
When the ignition switch is turned on and the engine is running, the system senses the level of voltage on the chassis 12 volt system. When this voltage goes 13.1 volts for approximately 2.5 minutes, as happens when the engine is running normally (normal alternator output voltage of a cold engine is approximately 14.4 volts), it will close the isolator relay providing charging current to the battery. This delay allows a cold engine an opportunity to start and warm up before having the heavy load of a discharged coach battery placed on it.

If the voltage should fall 12 volts for more than about 1 minute, the relay will drop out to feed all the alternators available output to the chassis battery to keep the engine running. This might happen when the alternator is not able to supply sufficient current to all of the loads and charge the coach battery at the same time. When the chassis voltage goes 13.1volts again, the relay will again close in about 2.5 minutes to retry to charge the battery.

So when you turn the key off, the BIRD is no longer connected to the chassis battery.

Also from the instructions:
If the voltage should fall 12.6 volts for more than about 1 minute, the relay will drop out to prevent the coach loads from discharging the chassis battery.

So the system is designed to separate the two banks when the voltage drops below 12.6v so that the chassis battery will not discharge into the coach battery or the other way around. There is no way that the BIRD can discharge the chassis battery once the ignition is turned off - if it is installed and working correctly.
I agree with you completely since I came across the same instructions on the Intellitec site. However, that is not what Thor did on this unit. The "ignition connection" is wired to the large right lug on the Trombetta and this lug is connected directly to the chassis battery. Thus it is hot all the time. I have seen one other picture of a Trombetta on this site and can see the wire leading from the battery lug to the BIRD the same as mine. It is not right but it seems Thor did it that way at least twice. So the ignition key position has no effect on power to the BIRD.

IF the BIRD is working properly it should open the Trombetta and separate the coach and chassis batteries but from the symptoms it appears that it is not. Thus the BIRD, if it is faulty could pull down both the coach and chassis batteries until the Trombetta drops out due to low voltage and then go on to drain the chassis battery completely.

I think no mater what the condition of the BIRD I will rewire it so it is on a keyed power supply as Intellitec suggests in their instructions. This would prevent the BIRD from draining the chassis battery but again the BIRD has to be faulty for this to happen unless it not designed to be powered permanently. I have no way of knowing if Thor wired all the Vegas's that way or just mine and a few others.
Travbob is offline   Reply With Quote
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