Notes on Signal Point Irrigation Computer Power Supply

We have been plagued by failures of the 9 volt battery that runs the irrigation system. When nobody is at the QTH this may go unremedied for many weeks, and has caused the death of many valuable trees and plants at Signal Point.

The Signal Point irrigation control computer in the laundry room has an enhanced homebrewed power source as of 30 November 2023. See the photo.

At the right is a USB 9 volt intelligent trickle charger that plugs into the bottom of four rechargeable 9 volt lithium batteries. All four are kept charged, as indicated by the green lights on the bottom of the batteries. The bottom two batteries are connected to the irrigation computer load (not shown out of the photo at the right). The top two batteries are kept charged but are not under load, serving as backups. To invoke the top two batteries you need only remove the black tape and snap the connectors onto the batteries.

The terminal strip at the left is fed by two at a time parallel connected batteries, and the blue and red wires at the left going upward connect direct to the irrigation computer.

When the commercial power is failed, the irrigation system will still work on the batteries. During the useful service life of these rechargeable batteries, we will never be without power for the irrigation. This will immensely help prevent the death of plants and trees.

New rechargeable batteries can easily be installed by snapping the old ones out of their holders.

The USB trickle charger can easily be replaced by loosening the nuts on the aluminum bracket.

Also, the irrigation controller can be reverted to classic operation by inserting a conventional 9 volt battery, but I can't see why one would want to do that. (I made a jig for the irrigation computer that mimics a 9 volt battery physically and electrically, and that is how the DC gets into the irrigation computer.)

IF YOU NEED TO REMOVE THE IRRIGATION COMPUTER FROM THE VALVE BODY BY PULLING IT UP AND OUT, FIRST CUT THE TIE WRAPS TO GIVE SLACK IN THAT DC WIRING.

Here's a wider photo including the irrigation controller.