Installation & Electrics — Batteries

For meters and timers

The battery-powered devices in a grow room are exactly the ones you rely on: the thermo-hygrometer, the pH and EC pen, the timer with backup, the remote. A flat battery usually announces itself when a reading looks odd, and by then you have been steering on a wrong number for a day.

The button cells are in your meters

The Varta CR2032 lithium is the most widely used button cell in the world and sits in pH and EC meters, motherboards and cycle computers among others. The Camelion LR44 comes in tens and is the standard cell for pH and EC meters, watches and calculators. Keeping a strip of those in the drawer pays off at exactly the moment you want to measure and the pen will not wake up. Which of the two your meter uses is in the manual or under the cover; they are not interchangeable.

The ordinary sizes

From Varta High Energy there are AA and AAA in fours and C and D in twos, plus a 9V block. AA and AAA come in a Single Press Out blister, which you push them out of one at a time rather than tearing the whole pack open, keeping the rest dry and in order. C, D and the 9V block are the sizes for equipment with a large constant energy demand.

Where they sit in the grow room

Meters and hygrometers are under Measuring & Control, and that is also where a flat cell costs most: a meter that will not switch on is obvious, but a meter drifting on a nearly flat cell is not. When in doubt replace the battery first and recalibrate after, in that order.

Frequently asked questions

Which cell is in my pH meter?
Usually a CR2032 or a set of LR44. Check the manual or under the battery cover; it is printed on the cell itself, which is the most reliable source.

Why lithium rather than alkaline for a button cell?
A lithium cell holds its voltage flat for longer, which matters in a measuring instrument: an alkaline cell tails off gradually and your reading tails off with it without the device saying so.

How do I store spare batteries?
Cool and dry, in the packaging, and not loose in a drawer with metal. A blister you open one at a time keeps the rest separated, which is exactly what that packaging is for.