Full discharge of NiMH's

[Henry Parr]

Are there any problems associated with allowing NiMH batteries to
fully discharge in circuit? For example, is longevity affected, or
ability to recharge.

The circuit in question has an op amp that will continue to draw
quiescent current should the user neglect to power off.

Henry

 

[Martin Riddle]

Rule of thunb is not to discharge below 1v per cell for either NiMH or NICAD.

Cheers

"Henry Parr" <parrh@ikinetic.com> wrote in message news:kl3d11p0du1tf43duvvhk7h9kej1gtftf4@4ax.com...

Are there any problems associated with allowing NiMH batteries to
fully discharge in circuit? For example, is longevity affected, or
ability to recharge.

The circuit in question has an op amp that will continue to draw
quiescent current should the user neglect to power off.

Henry

 

[Roger Lascelles]

"Henry Parr" <parrh@ikinetic.com> wrote in message
news:kl3d11p0du1tf43duvvhk7h9kej1gtftf4@4ax.com...

Are there any problems associated with allowing NiMH batteries to
fully discharge in circuit? For example, is longevity affected, or
ability to recharge.

The circuit in question has an op amp that will continue to draw
quiescent current should the user neglect to power off.

Henry

Especially if cells are in series, the first cell to go flat gets reverse
biased by the other cells continuing to pump current, which shortens its
life.

Roger

 

[keith]

On Sat, 19 Feb 2005 01:18:51 +0000, Martin Riddle wrote:

Rule of thunb is not to discharge below 1v per cell for either NiMH or NICAD.

NiMH (or NiCd) cells can be discharged right down to zero, but no lower.
The reason for the 1v rule of thumb is to avoid reverse-charging a
weak sister in a multi-cell battery. There isn't much charge under 1V (or
..9V), so not much capacity is lost by keeping the per-cell voltage above
..9V-1V.

--
Keith