Energizer Max Plus 9V Battery (PP3)

Max Plus is Energizer's alkaline line, and this is the 9V cell from it: the small rectangular block with a stud and a socket terminal side by side on the top face. One battery comes on the card. Nine volts is the odd one out in a household battery drawer, because it is the only common size that does not sit in a barrel holder; it clips on instead, which is why the snap connector on the device is usually the part that wears out first. The retail pack states a five year shelf life.

The 9V shape, known in the trade as PP3, is what a mains-free smoke alarm almost always takes, and it is worth keeping a spare in the house for the night the alarm starts chirping. The same cell powers carbon monoxide detectors, multimeters, radio microphones, guitar effects pedals and a good number of older wireless doorbells. If you are replacing one, pull the old cell out and look at the top: two terminals at one end, on a body roughly the footprint of a matchbox, means this is the cell you want.

Each unit of this listing is one cell, so there is no counting to do. We sell it in twelves: the minimum order is 12, in multiples of 12, which suits a landlord working through an annual alarm check across several properties, or a venue restocking a drawer of pedal and microphone spares. Alkaline chemistry holds its charge on the shelf much better than it stands up to a heavy continuous load, so a battery bought now and fitted in a year is doing exactly what it is good at. It sits alongside our other Energizer cells, including AA, AAA, C and D alkalines and the lithium coin sizes.

Will this fit my smoke alarm?

Most battery powered smoke and heat alarms take a single 9V block cell of exactly this shape, so check that the old one has two terminals close together on one end before you order.

Is this the same thing as a PP3?

Yes. PP3 is the common British name for the rectangular 9V cell, and you will also see it called a block battery or a transistor battery on older equipment.

Can I recharge it?

No. This is an alkaline cell and it is made for single use, so if you need to top a cell up repeatedly you want a rechargeable 9V instead.

How many batteries do I get?

One. Each unit of this listing is a single 9V cell on its own card, so simply order the number of cells you actually need.

Why does the minimum order say 12?

We buy and sell this line in trade twelves, so the smallest order is 12 units and quantities step up in multiples of 12 from there.

How long will it keep if I do not use it straight away?

The retail pack states a five year shelf life, so a cell bought as a spare now should still be usable when the alarm finally starts chirping.