How do you make rechargeable batteries last longer?

Thanks for your comment wavechange. You can indeed use devices such as phones and laptops containing lithium rechargeable batteries until they stop working and then recharge them without damaging the batteries.

With NiMH (nickel metal hydride) batteries – such as most AA and AAA rechargeables but also found in some devices such as handheld vacuums and power tools – you should recharge them as soon as you notice the performance of the device is dropping off. This will help preserve the cells in the long run.

Thanks for your comment Gerard. I’d be interested to know the types of devices you’re using your C and D size rechargeable batteries in which seem to discharge them completely.

You’re correct that NiCad batteries are no longer available. Nickel Cadmium cells (those containing more than 0.002% of cadmium by weight) can’t be sold in the UK for consumer use, following EU legislation in 2006. Although there are a couple of exceptions – including those sold in cordless power tools (until Jan 2017) and batteries intended only for medical equipment.

Gerard – I have also seen rechargeable batteries that refused to charge on a modern charger. You may well be right about the reason. I have disposed of all my old rechargeables recently – they were all over ten years old. They have served me well but new ones seem so much better.

Mixing rechargeable batteries is not a good idea because this increases the likelihood that one will discharge before others and be reverse-charged, as I have described above.

The only benefit of NiCD batteries over NiMH is that they hold their charge longer when not in use. Newer NiMH seem much better in this respect.

Sarah – What Gerard says is quite correct. The capacity of individual batteries in an apparently identical set will differ and this difference becomes greater with age. As the batteries are discharged, one or more can become exhausted while others are still partially charged.

The completely discharged cells are in a Grundig Concert Boy radio, that requires six type D batteries and a Yamaha electronic keyboard that requires six type C batteries. I do not use either very much, but that was why I decided to put in rechargeable batteries. There was formerly a Sony Radio Cassette player used daily that required 6 C rechargeable cells, but when the cassette part died, so did my use.
I think they expire through self discharge more than through usage. These issues have put me off extending my use of rechargeable batteries. Out of over 140 items using 254 batteries I have 6 items using 28 rechargeable standard cells, although built-in and special batteries takes my rechargeable item count to 23.