I use rechargeable batteries and intelligent chargers almost everyday and the capacity stated by the manufacturers are generally quite accurate depending how you treat the cell. Dry cell manufacturers however have been getting away with murder since they only have to describe the physical size i.e AA A B,C,D etc and a voltage but no capacity apart from heavy duty ! , have you ever seen a light duty battery sold ? ! No.

It would be akin to buying a gallon of 4 star petrol but you don't know how much is in the can. It can't be beyond them to state a capacity on an "urban cycle" just like an MPG for cars.

My husband recently felt a burning sensation in his pants pocket. He threw all the contents on the ground. He was carrying 2 AA batteries, some change (including pennies & quarters), and several keys-including the "keyless" key to our Honda. All the items were warm to the touch. One of the batteries and the car key were almost hot. There was no liquid leaking and no mark on his pocket.

My laptop has a lithium ion battery, which has served me well for a year or so. Lasting rougly 3 hours at 100%. But a few days ago, when my battery was removed from the laptop for half an hour or so, the capactiy dropped to 15 minutes. 

I know how these batteries "wear down" over time, due to corrotion of the lithium cathode and whatnot. But I would've expected a steady decline, rather than a sudden and extreme fall in capacity. 

Actual question: Why did the capacity of my lithium-ion battery suddenly drop from 3 hours to 15 minutes? And was it related to the fact that the battery was removed from the laptop.

The car battery shape and size is pretty standard these days, I know you can purchase smaller lead cell batteries but why not much larger ones?

For example I have an electric van with 24 separate batteries but it would seem to make sense to make a bigger battery(especially as the voltage is 48v i.e. 4 in series) is there any limitations on how big you could build a lead battery and if so why?

I understand that batteries have cells at 2.2v each so could you just create bigger cells(driving more amps) or would you need to have many separate cells?

I understand that obviously their are weight/manif issues, but if we could forget these for now.

What impact can this have on how they work or on the circuitry inside the remote control itself?

These particular batteries have been in use for more than 12 months, so they may well be nearing the end of their useful lives.

Nia and Steven Faulder, by email, no address supplied

As back-up for my digital camera, I fully charged a set of AA nickel-metal hydride batteries, and carried them in a battery box with no chance of accidental connection. When I needed them some time later, they had completely discharged.

Do rechargeable batteries leak their charge over time? If so why, and how long does it take? For extra back-up, I now carry a set of ordinary alkaline AAs as well.Joseph Oldaker, Nuneaton, Warwickshire, UK

I have five solar-powered lights in my garden. Something has spun silken masses inside their battery compartments, and in all five lights they are located at the negative terminal of the battery (see photo).

Is there a reason for this, or is it just coincidence?

Allen Lutins, Johnson City, New York, US