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Don Bradbury continues his run-down on battery types and their maintenance.
My own way of working is to generally use Ni-MH batteries where dedicated cells are not supplied or recommended. I reserve Alkaline batteries strictly for emergency use, and if I have to use them I'm glad to get back onto Ni-MH batteries as soon as I can because I know the Alkaline type are basically unsuitable for my high-drain main application which is digital cameras.
If Li-Ion batteries are supplied, then fine; they have many advantages and are fundamentally sound, but you should bear in mind that they will possibly have been designed for a specific duty in particular equipment. When the dedicated battery wears out, as it inevitably will, then what do you do?
The answer is go to the equipment maker and hope he still supports that equipment and sells that battery. If he doesn't, you could be sunk. Bear that fact in mind if you go for equipment that uses exotic, specially made battery types.
Whatever type of battery I use, especially of the Ni-Cad or Ni-MH variety, I try to run it down to minimum voltage before I put it on the charger. To do that, having in mind what I said about the equipment itself not having the capability to run the battery pack down to near exhaustion, I will stick the batteries in a cheap torch that takes their battery size, run them down until the torch light goes out, switch off to let the battery recover a few minutes, then repeat the process half a dozen times to ensure I have them close to totally drained.
My cheapo discharger features three bulbs, giving flashlight, warning flasher, and general illuminator, as shown. That means I have three bulbs to go at before I need to think about changing any that burn out, and all for a couple of quid. Of course you can buy specialist battery dischargers, and not too expensively. Even discharge/recharge combinations are sold.
Horses for courses
For my charging, I try to use the charger type recommended by the battery maker. I use AA size Ni-MH batteries when I can, or perhaps my older Ni-Cads, and charge them in a relatively fast £15 Uniross charger. Mine copes - via a switch - with both types of battery chemistry, and with battery sizes from AAA and AA to 'PP3' (6F22) 9 volt type.
The Ni-MH setting has a timer which switches off the current after a set time that is determined automatically by the inserted battery type/size. For AA size batteries, I have fully charged Ni-Cads within three hours; Ni-MH type take five hours. Anything faster than that and I'd be worried about unhealthy temperature rises within the cells, especially in summer. They already get pretty warm, but within tolerance.
For the timer to work correctly, the battery obviously needs to be essentially flat before recharging, hence the procedure I outlined. It works well, keeps battery temperatures tolerable, does not over-charge, and gives me a prime voltage and capacity each time I load fresh batteries into my cameras, or whatever, ahead of the day's work.
For my Li-Ion equipment, I invariably use the manufacture's own charger. It will have been designed to top up my batteries (no memory effect means I don't have to concern myself with running the batteries to exhaustion), and, again, I'm set up for the session.
Next time I'll conclude my look at battery types and their maintenance with notes on specifications and special procedures.
