Old Batteries and New Batteries?

[Saaby]

Depends on the light. Normally it is a very baaaaad idea but if it's your only option in an extreme emergency, it won't cause the light to explode immediately.

 

[Saaby]

Now thats just freaky...I come home from work and it just happens to be right as the server is sorting itself out so this post that I made several hours ago is on the top.

FREAKY!

 

[leddite]

won't the strong cells have the effect of trickle charging the weak cells, until they're all about the same? not a great idea with alkaline batteries but not horribly dangerous.

i've "heard" AAs pop inside a flashlight that ran them too low/hard. a problem with regulation. i think i'd want my flashlight to warn me or at least STOP working when the batteries were too low and a danger. hmmm.

 

[**DONOTDELETE**]

Say if you have a flashlight that uses 4 batteries and u have only 2 new ones, can you replace two of the old ones with new ones?

 

[Wingerr]

Actually it wouldn't trickle charge them, but it would start reverse charging them, once they run down to zero- That's not good for any battery type, and is generally what kills the rechargeables in a pack. (That's assuming the device uses the batteries in a series configuration; if they were connected in parallel, which is rare, it would tend to equalize the cells as you said.)

Just changing some of the cells can be done in an emergency; as long as you don't run them down to the point where the weak cells are discharged, it should be okay. The problem is that it may not be as apparent when that happens, because the newer cells may still continue delivering enough voltage to work the device.
By replacing all the cells at the same time, the point where they all poop out will be more obvious, since they'll tend to go about the same time.