Community Forums

Turbojack · 07-12-2017, 02:35 PM

The BIM is basically a relay switch with a brain. It is made to tie the chassis and the house batteries together to either jump start the chassis batteries or I believe to charge the house batteries while going down the road. I would have though that when the engine is running it would be closed all the time and let the engine generator charge all batteries but when I was at Entegra last year they told me the house batteries only get charged once they get to a certain voltage and when the batteries are charged it disconnects again. I am thinking the BIM is what is doing that.

Could have been a loose wire or could have been a bad connection in the BIM for it to have burned up.

Gasman 2 · 07-12-2017, 03:38 PM

Chuck I notice in the picture there is no wire connected to the terminal mark ignition on the BIM but there appears to be a lose red wire at the bottom left.

Dutch Star David · 07-12-2017, 04:50 PM

Quote:

Originally Posted by waterboy10

As I recall the chassis battery take precedence over the house batteries and it will give them priority on charging then will alternate between house and chassis.

True. I recently had the relay??/soleniod?? fail that changes charger to the chassis batteries after the house batteries are fully charged. Of course Coachnet had me change out the chassis batteries before actually finding out why the chassis batteries were not charging.

About $600.00 wasted.

757driver · 07-12-2017, 05:14 PM

Quote:

Originally Posted by waterboy10

As I recall the chassis battery take precedence over the house batteries and it will give them priority on charging then will alternate between house and chassis.

Actually it depends on whether you are driving or are plugged into shore power or running the generator.

When driving the alternator charges the chassis battery first and as long as they are above 13.2v AND the house batteries are below 12.6v then the BIM will allow the house batteries to also charge for a period of 1 hour.

If on shore power or the generator is running the house batteries are charged first but they are not necessarily full. They could be far from it. If the house batteries are greater than 13.0v AND the chassis batteries are less than 12.6v then the BIM will allow the chassis batteries to receive a charge.

757driver · 07-12-2017, 05:20 PM

Quote:

Originally Posted by Gasman 2

Chuck I notice in the picture there is no wire connected to the terminal mark ignition on the BIM but there appears to be a lose red wire at the bottom left.

Gasman you may be on to something here. You are correct, if that wire was not connected then that could explain why it burnt up.

If the generator is on and ignition is ON, then the alternator and battery charger (inverters) are fighting each other and the relay (BIM) should be turned OFF.

With that signal missing it could not stop the fight.

Gary.Jones · 07-12-2017, 07:34 PM

Thanks everyone!! I learned something brand new about my coach today. I have known for some time about the switching of charges and high amperage alternator when driving, but never knew how it was done or what did the switching, or where the B.I.M. is located.

Still a lot I don't know, but that list is one item shorter now. Thanks everyone!!

twinboat · 07-12-2017, 09:37 PM

That BIM probably cooked because the isolation relay was activated with 12 volts thru the boost switch, bad electronics or mis wiring.

During normal operation the relay is activated with battery voltage and then the BIM drops the hold voltage to 3 volts to keep it closed. It has less draw and runs cooler.

If the relay is held closed with a constant 12 volts, it gets very hot. Some report over 200 degrees.

As far as it overheating due to charging from multiple sources, if all sources are voltage regulated, will not melt a BIM or overheat a relay. Many RVs have 3 and sometimes 4 charging sources connected full time.

Dual inverter/chargers, dual converters, alternators and solar all work together in many MHs.

Many, like my MH, use a simple key operated isolation relay, with no voltage sensing controls. With my solar and both charging sources online, nothing overcharges.

Gasman 2 · 07-13-2017, 03:43 AM

The attached shows the proper operation of the BIM. So once Chuck gets the replacement hook up he can verify proper operation.

http://www.precisioncircuitsinc.com/...e-Shooting.pdf

757driver · 07-13-2017, 10:50 AM

Quote:

Originally Posted by twinboat

That BIM probably cooked because the isolation relay was activated with 12 volts thru the boost switch, bad electronics or mis wiring.

During normal operation the relay is activated with battery voltage and then the BIM drops the hold voltage to 3 volts to keep it closed. It has less draw and runs cooler.

If the relay is held closed with a constant 12 volts, it gets very hot. Some report over 200 degrees.

As far as it overheating due to charging from multiple sources, if all sources are voltage regulated, will not melt a BIM or overheat a relay. Many RVs have 3 and sometimes 4 charging sources connected full time.

Dual inverter/chargers, dual converters, alternators and solar all work together in many MHs.

Many, like my MH, use a simple key operated isolation relay, with no voltage sensing controls. With my solar and both charging sources online, nothing overcharges.

I would agree with you on the multiple charge sources normally not being a problem but Precision Circuits Inc (the manufacturer of the BIM) specifically states that it the ignition and generator are both on the BIM's relay must be open to prevent conflict from the alternator and the inverter charge at the BIM.

If the ignition lead to the BIM was not attached then it would have no way to send the signal to the BIM to open the relay with the generator ON.

lagoon410 · 07-14-2017, 01:46 PM

Guys, I've been out of town with the "Paying Gig". Just got in and saw the comment about the Ignition Wire. I had not noticed it as I was concentrating on the melted plastic and just glad to locate the problem. The new BIM has arrived and tomorrow the installation begins. I'll let you know how things work out.

I did speak with Entegra CS earlier this week and they felt that the problem was most likely due to a lose wire or maybe the previous owner and jammed pennies under the Boost Switch while driving to charge the house batteries. Seemed to be "trick" that he had heard of several times.

Gasman 2 · 07-14-2017, 02:57 PM

Chuck, I'm not as familiar with this BIM as others are here, but I would check for proper operation after you connect the new BIM up.
For that BIM to work it needs a good ground so you need to check that out as called out in the "check for proper operation" instructions .
The wire going to the gen set that is unconnected now shows current overloading as much as is discolored.
Hope you get everything working the way it should.
Richard

lagoon410 · 07-15-2017, 11:53 AM

Update for this morning. I have the new BIM installed and the first Operational Test is to verify the Boost Switch connects the two battery systems. I found a blown fuse for the Boost Switch and once this was replaced, everything checked out fine.

The 2nd test requires starting the engine..... I have charged the chassis and house batteries and the coach still won't crank. I do not get anything from the ignition / engine gauges.

Also, none of the light switches, window shades or slides will operate !

My main concern is to get the engine running. Does anyone know of a particular fuse or relay that would keep the ignition/dash gauges from working and the engine from turning over ?