More efficiency, sticking NImh in the cooler?

[prState]

Here's an blurb from Yahoo Answers I found:

NiMH and NiCd batteries self discharge at a MUCH faster rate than alkaline batteries. In fact, at "room temperature" (about 70 degrees F) NiMH and NiCD batteries will self discharge a few percent PER DAY. Storing them at lower temperatures will slow their self discharge rate dramatically. NiMH batteries stored at freezing will retain over 90% of their charge for full month. So it might make sense to store them in a freezer. If you do, it's best to bring them back to room temperature before using them. Even if you don't freeze your NiMH batteries after charging them, you should store them in a cool place to minimize their self discharge.

Okay, so if I had been sticking my Giant battery pack in the fridge (don't know what you call them in the UK) over the past 4 years, would I have cut down significantly on my energy costs?

And what about the Li-ons?

 

[Miles]

Here's an blurb from Yahoo Answers I found:



Okay, so if I had been sticking my Giant battery pack in the fridge (don't know what you call them in the UK) over the past 4 years, would I have cut down significantly on my energy costs?

Depends how much it costs to run your fridge

 

[flecc]

It's not worth it for most users.

The self discharge of good quality modern cells like the Panasonic ones in your Giant battery is only about 1% per day, and most use their bikes regularly enough for that not to be serious. A "few percent a day" mentioned there applies to an earlier type of NiMh which has not been made for years.

More importantly, batteries operate at very low efficiencies at low temperatures. Since it would take several hours to bring the deeper innards of a battery fully up to room temperature after removing it from the fridge, a very high level of forward planning would be involved. The alternative of using it while still cold would result in more wastage than gain, plus a much lower level of performance.

Since getting the whole of the battery fully down to temperature would take several hours, and getting it back up several hours, most would never manage to fully gain anything anyway. Basic precautions like not parking the bike with the battery in direct sunlight are quite enough in most countries, but in the UK we scarcely need to avoid such a rare event as sunlight.

So once again this Yahoo entry advice prompts something I've mentioned previously, the importance of not placing too much credence on stated theory without questioning, as you've rightly done with this posting prState, and an examination of the practical issues involved.
.

 

[derrick7]

Cool

We call them fridges (5 degrees C) in the U.K. as well, as against freezers (-18 degrees C) I would hestitate to put any sort of battery in a freezer!
Batteries are like people, they work better when they are warm.
"Two nations divided by a common language" so said George Bernard Shaw, not this time!

Derrick - Llanberis