I thought this would be good to have availiable for basic information as I have had problems in the past with my isolator/separator operation. This may be somewhere else on the forum but seems this is the best place to post about it. Note that this is what is offered as of 2006, older model SMB's could have a different unit.
This was my responce from SMB about Basic operation:
I have replied below in all CAPS.
From: Dave Boyer [mailto:firstname.lastname@example.org]
Sent: Monday, March 17, 2008 12:18 PM
Subject: 12 VDC plugs/isolator
Peter I have had some people ask how the isolator operates and I think this is how it works. (This is from Sure Power). I would like to verify this for for future troubleshooting. I also need to know how the plugs are wired.
According to Sure Power:
The battery separator is designed for use in multi-battery applications as a solenoid priority system to protect the chassis charging system from excessive loading while allowing auxiliary batteries to be charged. The battery Separator has two basic operational characteristics:
1. Assist in engine starting.
When the starter is activated, the battery separator compares the voltage of both banks. If the chassis battery is lower than the auxiliary battery bank, the battery separator will engage allowing the auxiliary battery bank to aid in vehicle starting. (The start signal must be at least three volts for this operation to occur.
2. Protecting the charging system.
Once the engine has been started, the separator monitors the chassis battery (twin starting batteries in the case of a Ford diesel) and charging system. When the charging system reaches 13.2 volts indicating a charged main battery and functioning charging system, the battery separator will engage, connecting the auxiliary battery bank to the vehicle charging system. If the drain on the charging system by the auxiliary battery bank reduces the system voltage below 12.8 volts, the separator will disconnect the auxiliary battery bank, thus protecting the chassis charging system. The process is repeated until the charging system is turned off. A delay function has been incorporated in the circuit to prevent the separator from reacting to momentary voltage fluctuations and chattering. The priorities are to assist in starting, if required, and to protect the charging system from excessive drain.
I assume the types we have in our vans are the bi-directional type units because if you were to leave something on in the van you would want to protect one bank or the other depending where the draw is coming from. Of course if you leave one item on pulling off the starting batteries and one item on pulling off the house battery the isolator canâ€™t do much for that. I do know that SMB upgraded to a 200 amp model in my van and I think it is made by Sure Power. YOU HAVE THE 200 AMP MODEL1315-200
So Peter is this correct? Does the isolator work in both directions? YES.THE SEPARATOR WILL ALLOW THE HOUSE BATTERY TO AID THE STARTING BATTERY IN CASE OF EMERGENCY.THE PROCESS CAN NOT BE REVERSED,THIS IS DONE TO PROTECT THE STARTING BATTERY.
Does it work off the key or ignition? IT ENGAGES AFTER THE KEY IS TURNED TO THE ON POSITION
Will the battery banks, (the starting and house) stayed tied together until one or the other drops to 12.8 wherein the isolator will open and separate? YES
Do the 12v accessory plugs in back come off the house system? YES, THEY DRAW FROM THE HOUSE BATTERY
Iâ€™m sure that the dash 12 plugs come off the starting batteries, correct? CORRECT