For each size, there are various optimisations - ones that cram in as much capacity (run time before flat) at the penalty of thinner metal and a lower peak current,  ones that can deliver a higher current, at less capacity or those that have a long shelf life  (low self discharge rate) versus capacity.


Now you need to decide how you will use and charge your devices - will they be charged and forgotten for weeks, or kept on charge until needed,  and is your kit especially demanding?

Also be aware that some equipment designed for 1.5v cells that start new at 1.6v and fall to 1.1-1.2 when nearly dead sees a fully charged rechargeable at 1.2- 1.3 volts as half flat and will warn of low battery, even if it is really in perfect working order. It may be worth checking with the makers if 1.2v rechargeable cells are likely to cause issues..

For each size, there are various optimisations - ones that cram in as much capacity (run time before flat) at the penalty of thinner metal and a lower peak current,  ones that can deliver a higher current, at less capacity or those that have a long shelf life  (low self discharge rate) versus capacity.


Now you need to decide how you will use and charge your devices - will they be charged and forgotten for weeks, or kept on charge until needed,  and is your kit especially demanding?

Also be aware that some equipment designed for 1.5v cells that start new at 1.6v and fall to 1.1-1.2 when nearly dead sees a fully charged rechargeable at 1.2- 1.3 volts as half flat and will warn of low battery, even if it is really in perfect working order. It may be worth checking with the makers if 1.2v rechargeable cells are likely to cause issues..