Considering that recharging NiMH AA battery takes 4 watt-hours, and 1kWh of power costs ~15 cents (I don’t live in UK, used a Google search - correct me if I’m wrong!), you can recharge NiMH AA 250 times at price of 1 such battery.
I’m paying around 33 cents (22p since the last price rise) for a kWh of electricity - so you’ll only get about 125 - well about half that since rechargeables are not hugely efficient, on NiCd I used o reckon on using double the electricity that I’d put into the cells. NiMH are better but it is still of the order of 30-40% more.
I calculated inefficiency into account, real energy capacity of typical 2000mAh NiMH = 2.4 watt-hours, so 4 Wh requires just 60% efficiency, in real world it’s usually more than that.
Dont forget also.Youve got to buy the rechargeables and a charger.Then thers ones time and trouble doing it ,shoe leather,calories burnt,loss of heat opening doors if ther in an outside building,missing the last 3minutes of a four hour film while you check them,mental pressures waiting and wondering….
i found regular alkaline last a lot longer than my duraloops. the kids leap pad died and wasnt around a charger so i put some regular duracells in it, id say they lasted 4x as long as the duraloops. but i still use rechargeable in it as long as its possible.
my flashlights i use ultimate lithiums. kids toys and electronics that are heavily used get rechargeable. and kids toys that will most likely get thrown in a year or break or not so important get the alkaline
lowes had 30xAA for $4 on BF sale… picked up 5 boxes