All you did wrong was not follow the directions. Step 7 says to connect
a ground wire from one of the 3 prongs to vehicle chassis ground. The
logic inside the unit needs power AND ground.

Mark

Dave Vickery wrote:

> I installed a shurpower 1315 isolator. It is so simple, I don't know how I
> messed it up.
>
> I hooked up main battery + to one terminal, Aux batter + to the other
> terminal.  I left the 3 little switch prongs alone, as I don't need it
> manually switchable, just want it to intelligently charge the aux battery.
>
> After a few days, my aux battery was dead and I realized something wasn't
> working.  I checked voltage at the terminal from the main battery, about
> 12.5 not running, around 14 running. A little hard to get it exact on a 50
> volt scale analog meter.  Only 5 volts at the other terminal, running or
> not.  I realized the main and aux battery + wires were connected to the
> wrong terminals, so I reversed them.  Same result immediately after.  I
> would have expected to see 13+ volts going into the dead battery.  Is that
> right?
>
> There isn't a ground terminal on the isolator, so I just put a small screw
> into it screwing into the battery box metal and thought that would be
> sufficient.
>
> Could reversing the terminals hurt the isolator?  Should I be getting
> charging level voltage when the battery you are charging into is dead?
>
> Thanks for anyone's help.
>
> Dave in Denver
> Electrically challenged
>
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