All good information. Great comment about not putting the diode on
the battery or it can't charge. Looks like you picked a good sized
diode (9 amps).

I'll add one highlight about the orientation of the battery which was
kind of buried within the answers above. A diode's symbol looks like
an arrow with a vertical line at the point.

I hope this "text-ture" comes through if your news reader uses a mono-
spaced font.

| /|
| / |
Cathode ----| |---- Anode
To Equip | \ | To Battery (+) terminal
| \|

This arrow "points" along the current flow. The vertical line
(cathode) is represented by the painted ring on the diode.

The current flow is from positive (+) to negative (-). That is, from
the positive terminal of the battery, through and in the direction of
the diode's "arrow", through the equipment and back to the negative
terminal of the battery (or ground). Physicists might disagree with
this description of current flow but EE's won't. Again, the arrow and
line should "point" away from the battery (+) terminal and towards the
equipment.

It is pretty simple because if you don't do it right, nothing will
work! Test with a voltmeter. If nada volts, then just turn the diode
around! So you won't be surprised, remember that you will "loose"
1/4V (Vf = 0.25v)across the diode.

My $0.02. Good luck.

- John

PS - Glad you are using Powerpoles. Great stuff that!
PPS - Full disclosure - I don't use diodes. ;-)