Orion MBR70 battery isolator

[oPossum]

I got one of these many years ago, but have not used it. I assumed it was a DC to DC converter that would compensate for wiring losses, but it is just a solid state switch. A conventional battery isolator can be in the feedback loop of the alternator, so there is compensation for the diode drop. It seems like the MBR70 will never bring the secondary battery up the the same state of charge as the primary due to losses in wiring and the MBR70 itself.

Has anyone used this? How well does it work? What do you think of the design?

Here is the Schematic (drawn by me, so it probably has some mistakes).

[Perry Babin]

It looks like it would loose ~0.6v due to the operation of Q5 but that doesn't mean the auxiliary battery wouldn't be fully charged. A lower charging voltage will reduce the rate of charge but the battery will still fully charge (12.6v is fully charged) as long as the charging voltage is ~13v.