Regular Clunking Sound while parked

[16ACE27]

"transfer switch noted on the schematic that is associated with coach batteries."?

Do you mean battery disconnect relay?

[Bill Johnson]

Mine has done it since new during the day with the battery switch off and the solar panel charging the batteries

[16ACE27]

Originally Posted by Bill Johnson

Mine has done it since new during the day with the battery switch off and the solar panel charging the batteries

You don't have the same coach. But you are hearing your BIM switching.

[Bill Johnson]

Originally Posted by 16ACE27

You don't have the same coach. But you are hearing your BIM switching.

That's what I figured, it's not very loud

[Frank88]

After downloading the electrical schematic from Thor and crawling around under the RV looking for relays or solenoids that might be making the noise, the only thing in the area is Precision Circuits BIM160 (Battery Isolation Manager). I downloaded the Spec/ info sheet for the unit and while it has a lot of info on how it works, one thing was not making sense. It states in 2 places that it doesn’t make noise.
“This long term monitoring of the batteries prevents the annoying relay clicking that
exists in simpler isolation modules today.” So if the BIM160 does not make noise, what is???
I have been trying to reach the tech line at Precision Circuits for the last 2 weeks to confirm this and finally got a tech on the phone today and he was very helpful. However he said the product info sheet is wrong and the BIM160 does in fact make a clicking noise when switching power. The noise I hear seems to be louder than a relay/solenoid, but probably because it is bolted to the frame. He also stated that the unit will look at the voltage of both the front and back batteries and if the front is lower it will connect them for a short time to balance the load, and that is what we hear.
Here is what is on their spec sheet.
“The BIM monitors the battery voltage of both the chassis and coach batteries over long periods of time. If it senses a charging voltage, it connects the two batteries together. If the charging system is drastically overburdened, the batteries will be isolated, however, if the BIM sees a long term charging of both batteries it will allow the batteries to remain connected and allow the charging system to do its job. Once the batteries have charged for one hour, the BIM will isolate the batteries to prevent overcharging, and will only reconnect the batteries for charging if one of the batteries drops to approximately 80% charge, and the other is being charged. This long term monitoring of the batteries prevents the annoying relay clicking that exists in simpler isolation modules today. The BIM does not guarantee 100% battery charge, but prevents harmful battery charge levels.”
Interesting… as of tonight the web link for the BIM160 is no longer active. Maybe they are going to update it so it no longer says the unit does not make noise…….

[JeffreyLee]

Frank88 I thank you for your efforts. This tracks with what I was finding and thinking. I too read that it was supposed to be solid state and therefore no relay clunking sound so I figured I got stuck with an older model that had a relay. Appreciate your posting this so I can stop chasing my tail.

[Jimbo56]

Does the clunk affect operations of the coach? If not, drink another beer.

Does it wake you up at night? If so, white noise.

Does it affect your quality of travel? If so, sell it.

[RACarvalho]

Check the BIM (battery Isolation) connections.
Thor tends to connect these with the battery cables inverted and that cause a higher frequency of "connections".
After I changed the wires according to the BIM manual, that frequency was reduced.
The clunks will not go away, just the frequency will be reduced.
Small battery bank, that needs to be recharged all the time also cause that high frequency of connections.

Everytime BIM connects or disconnects you will hear a "clunk"

[dkoldman]

Originally Posted by Jimbo56

Does the clunk affect operations of the coach? If not, drink another beer.

Do you get to do this every time you hear the clunk? Dang; I want one of those BIMs in my coach

[Frank88]

RVCarvalho, Thanks for bringing that up. I did see a post about this a month ago on another thread but forgot, so I will check the connections.

[16ACE27]

The BIM should not periodically shift state except when charging is happening. If the chassis battery is being dragged down by a load the BIM will NOT connect the banks together to "share the load". It will only connect them together if the house batteries are being charged. A MAJOR purpose of the BIM is to isolate the battery banks from each other when no charging is happening. "Sharing the load" when boondocking results in both battery banks being dragged down instead of just one.

[RACarvalho]

Originally Posted by 16ACE27

The BIM should not periodically shift state except when charging is happening. If the chassis battery is being dragged down by a load the BIM will NOT connect the banks together to "share the load". It will only connect them together if the house batteries are being charged. A MAJOR purpose of the BIM is to isolate the battery banks from each other when no charging is happening. "Sharing the load" when boondocking results in both battery banks being dragged down instead of just one.

That is true IF the cables are correct installed as per the BIM manual.
If they are reversed, the BIM logic will consider that the CHASSIS battery is the house and the house is the chassis.
The question is: Who have priority?
I don't know the BIM logic but if I was the BIM programmer I would set the CHASSIS as priority (means should be the one that can't be depleted) for if you have chassis , even with house depleted you can start the engine and recharge.
That EXPLAINS my experience:
When we first got our MH out of the dealer, the BIM would be flipping all the time.
That is because it was thinking the house was the chassis so any minimal drop in charge would make it link because it wanted to top off the what it thought it was the CHASSIS but in fact is the house (being draw all the time)
After I changed the cables, it stopped doing that.

[16ACE27]

Originally Posted by RACarvalho

That is true IF the cables are correct installed as per the BIM manual.

Agreed! That's what Precision Circuits expects.

[Frank88]

I was expecting that the batteries would only be connected when there is input power. However I asked that when I called and spoke to the tech and he said no, the Bim160 will try and keep the front battery voltage up even when not plugged in. But you're right, if the connections are backwards, that would explain all the clicking activity..... I will be crawling under my rig when the weather clears up and checking the connections.