Rechargeable batteries - saving money?

timestar

Has anybody actually done the maths on whether using a battery charger and rechargeable batteries does actually save money. When you factor in the initial cost of the charger and batteries, and the cost of the electricity for each charging session, is there really a saving?

Marty_J

Battery chargers don't use up that much electricity, maybe a few pence per charge, so I'm sure they do work out cheaper.

You could work it out yourself though; look at the electricity usage on your meter, start recharging some batteries, then look at it again. Subtract one from the other and that's how much electricity the charger uses. Once the batteries are charged, work out how much time it took, then you can work out how many kilowatts it takes to recharge the batteries. Then just multiply that by the cost of your electricity per kilowatt.

robredz

Factor in the capacity of the rechargeables, as the cheapest ones usually run down pretty quickly 2500mah is reasonable for AA size

timbim_2

Or look at the kilowatt rating on the transformer. That will give you a maximum figure, working from that will give you a reasonable over-estimate, which is what you want once you factor in the fact that you won't always stop using it once they're fully charged, so the transformer will be generating heat, "wasting" energy. (not really, it heats the room, saving the central heating from coming on; conservation of energy thwarts most of these green arguments)

John_Gray

Rechargeable will be cheaper in the long run, provided you can be bothered to recharge them every time. The usual snag is that they have a lower voltage than the non-rechargeable ones - which can occasionally matter.

Lorian

The other issue to factor in is with traditional rechargeables over time they loose their charge if they are not used, so you end up having to charge them again. There are newer (more expensive) types that are more resistant to this.

davetrousers

John_Gray wrote: »

The usual snag is that they have a lower voltage than the non-rechargeable ones - which can occasionally matter.

I heard that they have a lower resistance than standard batteries. So it doesn't really matter.

V= IR

so I= V
........R

timbim_2

And in everyday terms, I stands for current, or the rate of flow of charge.