Boost relay problem

[Monaco_hwy]

I am getting a handle on this.

It seems to me that when you crank the engine, the BIM will open if in auto mode. This is because the battery voltage will drop below 12 volts due to the high current draw causing the BIM to open. If your chassis batteries are weak or have failed, you will not be able to start. A dash mounted boost switch will solve this problem.

A switch like the Blue Sea 2146 looks ideal, even the graphic is correct.
https://www.bluesea.com/products/214...ch_-_ON-OFF-ON

[peskyfeller]

Originally Posted by Monaco_hwy

While trying out the features of my new-to-me MH, I ran the chassis battery down to where I could not start the engine. I tried the boost switch but no "boost". The house batteries were fully charged.

I chased down the problem. The house batteries were at about 12.6 volts. When I tried the boost relay the voltage on the coil would only be about 10.7 volts which is not enough to fully actuate the relay. If I used a jumper wire at the relay, then it would pull in fully and I could start the engine.

It seems that the long run of wire from the switch on the dashboard to the boost relay has too much voltage drop to work properly. I am thinking of adding a Bosch type relay to solve the problem.

Has anyone else has this problem?

I had the same issue with my 2003 Bounder. I started the generator and that gave me the power to start the engine.

[Monaco_hwy]

Originally Posted by peskyfeller

I had the same issue with my 2003 Bounder. I started the generator and that gave me the power to start the engine.

I tried to start my generator, but it uses the chassis battery as well, so it would not start.


My solution was to use jumper cables from the house battery to the chassis battery.

[THenne1713]

FYI: Voltage drops on every battery under heavy load. Dead battery is a heavy load to a charged battery. How far it drops under spec load, is part of battery load testing. Pretty sure most test says load test drop over 10.5vdc= pass; <10.5= fail? It take a few minutes 3, 5, 10 with boost connected for dead battery VOLTAGE to rise to be able to crank. As dead charges, amps decrease, and voltage rises.

[AirBossdavid]

When I switched my house batteries to lithium (1,120 ah) I did not want the alternator directly charging the house batteries so I removed the solenoid and replaced it with a 500 amp manual battery switch.

I can connect the 2 systems together to boost or charge. Advantage is I can leave them connected when it’s advantageous, but I control when. I also put in 2 dc to dc chargers so my alternator never gets loaded more than 80 amps to charge the house.

[John Kaehms]

The picture appears to show a “Trombetta” solenoid. Our coach came with one of these solenoids. Like earlier posts have said the internal contacts burn and do not function properly. We changed the solenoid to another “Trombetta” model with supposedly better contacts. That solenoid also failed. Finally we up graded the solenoid to a “Blue Sea” marine grade model #9012 rated for 250 amps continuous and 1000 amps intermittent (30 seconds). The “Blue Sea” solenoid has been functioning perfectly for the past four years.

Stay safe out there..
JK
Monaco Cayman

[Monaco_hwy]

Originally Posted by twinboat

Take all 3 components out, connect the alternator output to the chassis battery, but the BIM225 isolation solenoid and place the cables on it.

The BIM225 will handle bi-directional charging and boost start function.

Don't get the Li- Bim225, just the standard one, unless you plan on going lithium.

I have started the conversion of the high current DC panel to use a BIM device. This is what I have done so far:





I have the high current connections done. I am not sure about the SIG connection.

The BIM diagram shows 2 options:

Option 1 is to connect the SIG terminal to 12 volts with a (boost?) switch.

Option 2 is to connect the SIG terminal to ground with a (boost?) switch.

Do option 1 and 2 do the same thing? That is, cause the BIM to close like a boost relay. What is the purpose of the "IGN" terminal? I know that you are supposed to connect it to 12 volts controlled by the ignition switch. But what does IGN do?

[shootist]

Originally Posted by Monaco_hwy

I have started the conversion of the high current DC panel to use a BIM device. This is what I have done so far:


Attachment 382344


I have the high current connections done. I am not sure about the SIG connection.

The BIM diagram shows 2 options:

Option 1 is to connect the SIG terminal to 12 volts with a (boost?) switch.

Option 2 is to connect the SIG terminal to ground with a (boost?) switch.

Do option 1 and 2 do the same thing? That is, cause the BIM to close like a boost relay. What is the purpose of the "IGN" terminal? I know that you are supposed to connect it to 12 volts controlled by the ignition switch. But what does IGN do?

IGN is usually to cut out the combiner relay when you start the engine. It goes to key start or the starter solenoid from key start . Keeps high flyback voltages from damaging your coach electronics. Double check me as I am not familiar with your relay in particular