Re: Why doesnt SMB isolate the radio/CD player?
The answer is the clock, display, and relay pull off the starting battery system when the radio switch is on, so if you leave it on for some reason there is a possibility that over a long storage, both battery banks could be drained. If the van is to be stored, the best choice is to isolate each battery system.
With the back radio switch on, most of the load is applied to the house battery but depending on the type of stereo used, I'm told it can pull up to about an amp off the starting batteries as well.
It's possible to rig the radio all on one or the other and even install a "kill" switch but you will loose all the pre-sets, audio settings, clock and even maybe have to re-sinc the phone's bluetooth each time the kill switch is opened. That would be a PITA. Most people drive their vans so the radio memory is wired directly to the starting system, but for those who camp and use the audio system, most of the load is shed to the house battery system when using the back radio switch so in the morning you can still start the vehicle. Anyway that's what I was told.
In most cases the SMB rear radio switch should run accessories such as additional amps or players but some load will always pull from the starting batteries as well.
Hope that helps.
2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer
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