Ditto, I just installed my new SurePower 1315 battery separator today. I
also put it in the aux battery compartment under the driver's seat.  I
placed it in the front right corner of that space. It fits easily next
to the Optima Yellow top. Hopefully, the 1315 will help the Optima last much
longer than the relay system I used previously. So far so good. BTW, I
noticed the clicking sound coming from the 1315 when I started up the
engine.