Thor Forums

[AAL787]

Originally Posted by bevedfelker

There have been a lot of responses on various threads of this forum about what (generator, shore power, and engine alternator) charges what battery (chassis, house) when. In researching technical topics for the Axis/Vegas Owners' Manual I compiled I found information about the Bi-directional Isolator Relay Delay (BIRD). Reading about the BIRD I had the impression that it sensed voltage from the alternator, generator, or shore power and automatically switched charging current to both the chassis battery and house batteries. This left me confused when so many answers to questions on this forum implied that the chassis battery was not charged when running the generator or on shore power.

To try to get a good answer, I sent the following email to Thor Customer Service: "I have a question regarding battery charging -- both chassis and house batteries. I know the chassis battery is charged by the engine alternator. I also know the converter charging circuit charges the house batteries when on shore power or the generator is running. Here are my questions. I have asked several owners and I've gotten more and different answers than I've had questions: 1. Does the alternator provide power to charge the house batteries when driving down the road? 2. If so, dose the USE/STORE switch have to be in USE? 3. Does the converter provide power to charge the chassis battery as well when on shore or generator power? 4. Does my 2015 Vegas 24.1 have a Bi-directional Isolator Relay Delay (BIRD) or is there a BIRD-like circuit in the Battery Control Center (BCC)? 5. Does the BIRD function in both directions; that is, alternator power going to both chassis and house batteries as well as shore/generator power going to both house and chassis batteries? 6. Can I gat a Production drawing of the BCC and also the BIRD (if there is one). Sorry for the myriad questions but how the batteries charge and from where they get their charging power is driving me crazy."

Today I received the following answer from Thor: "Hi Ed, Thank you for contacting Thor Motor Coach. When your coach is going down the road with motor running, it is charging all the batteries – chassis and house. When the coach is sitting plugged into shore power or generator running it is also charging both – chassis and house batteries. For this to happen, motor running or plugged in the USE / STORE switch needs to be in the USE position. I believe the Bird or Bi-directional relay for your coach is under the hood on the driver’s side. But the main part is that yes the system should charge all batteries going both ways. Hope this helps."

When the BIRD senses 13.1 volts for 2.5 minutes on the chassis battery the relay isolator will close sending charging current to the house batteries (alternator providing charge to house batteries. Going the other way when on shore power or running the generator when the BIRD senses 13.1 volts for 2.5 minutes on the house batteries the relay isolator will close sending charging current to the chassis battery (generator or shore power charging the chassis battery).

Given this, the BIRD should keep all batteries charged when the engine is running, when you are running the generator, or when you are on shore power. For this to work for the house batteries, the USE/STORE switch must be in USE. Atch from Intellitec explains BIRD operation.

Sorry for the long explanation, but from the myriad questions regarding battery charging on the forum I thought this would be helpful.

BIRD is the word!