Usefully Useless

This post will focus on a large source of highly polluting chemical waste which households generate largely through incompetence.

No, not Gordon Brown’s underwear, but batteries. Disposing of them is difficult and highly polluting and most people spend more money on them and generate more chemical waste than they need to.

It’s almost a scandal that battery companies go to great lengths to avoid disclosing the actual capacities of their batteries. I’m yet to see a primary cell (non-rechargeable) state its capacity in either packaging or on the unit itself. All rechargeables state their capacity both on packaging and on the cells.

We measure capacity in milliamp-hours (mAh), a battery with a capacity of 1,000 mAh can deliver 1,000 milliamps for one hour, or 100 milliamps for ten hours.

Zinc Chloride

The first kind of battery, and the most common, is also the least suitable for almost everything. It’s the zinc chloride battery, also known as “heavy duty”, “extra heavy duty” and “super heavy duty”. They’re the ones you can buy at markets and get 20 for £1.

They typically have capacities around 300 to 700 mAh for AA size. They’re the biggest selling batteries and also by far the most expensive, both in terms of your wallet and in terms of environmental impact.

A pack here, labelled “Panasonic” and in red and black have a 670 mAh capacity as measured by me and cost me £2.99 for 12. That’s a total capacity of 8,040 mAh or 2,689 per pound.

Zinc chlorides are best suited for shop shelves and worst suited for any electrical device. They’re especially bad suited for lighting (e.g. flashlights, torches) and cameras, especially digital cameras. The capacity of a zinc chloride in a digital camera may be as low as 100 mAh.

Price per 1,000 mAh: 37.2p

Alkaline

Alkalines have very high capacities, usually 2,000 to 3,000 mAh for an AA cell, but are also a little more expensive. They’re always labelled as “Alkaline” somewhere.

A pack of 12 AA alkalines from Boots in black with orange text and Boots own brand will set you back £6.84 and I measured them to 2,400 mAh each. That’s a total capacity of 28,800 mAh or 4,211 per pound, around half the price of the zinc chlorides above.

Alkalines are best suited for remote controls, flashlights and torches, kids toys, and almost any other electrical appliance. They’re not suited for digital cameras, the high power draw of a digital camera reduces an alkaline’s capacity to around a quarter of what it should be.

Price per 1,000 mAh: 23.8p

Nickel Metal Hydride (NiMH)

These are rechargeable batteries and vary in capacity from those cheap Energizer things in Tescos at 1,300 mAh to the more expensive 2,500 mAh units which can be bought from electrical stores.

Some places still sell nickel cadmium batteries, which have capacities much lower, often around 400 – 800 mAh. They’re still a fairly good deal and I’ll include them in the final cost summery.

The single most important thing to do is to buy a smart charger, these are often marketed as “intelligent”, “smart” or “automatic”. The number one cause of rechargeable battery death is overcharging. If you don’t have one and can’t yet get one, then undercharge; You’ll do no harm.

A pack of four 2,100 mAh cells set me back £8.49 and they’re rated for 1,000 cycles, improving their life to an “effective” 2,100,000 mAh. Of course their capacity does decline in time, reaching about 75% of its initial capcity before the battery fails completely. So I’m going to list them as 1,800,000. I’m also going to add the price of a four-cell fast smart charger (two hours charge for most batteries, four hours for these) at £12.99.

For the NiCd batteries, I picked up a set of four 800 mAh cells with their own charger (not a smart charger, but the instructions were clear enough as to how long to charge for) for £4.99 from the local Netto.

Of course the price of mains electricity is a factor, so I’ll include that too. 1,000 mAh is 1,500 mWh (the amps being replaced by watts once we factor in the voltage), which takes about 2,000 mWh to charge up, or just 2 Wh. The price of 1,000 Wh is about 14p, so each type has 0.028p added to it.

Rechargable batteries are very well suited for digital cameras (and other cameras) and for all other electrical devices. They’re less well suited (but still acceptable due to their phenomenally low price) in remote controls

NiMH Price per 1,000 mAh: 0.02801p
NiCd Price per 1,000 mAh: 0.02801p

In Closing

We can all do our bit to be greener. As seen above, for every £1 that you spend on a rechargeable battery, you’d need to spend £8.50 on alkalines for the same amount of power. You’d also generate the waste of 4 batteries for rechargables but over 20 for alkalines. Those numbers are even worse for zinc chlorides.

So not only do you cut down on highly toxic chemical waste, but you also save quite a fair amount of cash. Works for me.