The end discharge voltage (generally 1.0 volt per cell for NiCd and NiMH
cells) is measured under load. After disconnecting the load, the voltage
will typically rise substantially, but its value isn't of any significance.

It's usually not recommended to discharge below 1.0 volt, but it doesn't
seem to cause any harm, at least if it's not done really often. I think
a cell is more likely to grow dendrites and short if it's left in an
extreme discharged state for an extended period, so it's probably a good
idea to put at least some charge back in before too awfully long if
you've discharged it particularly deeply. What is harmful is reverse
charging of the cell. But that happens only when you have an external
source of current, like other cells in a series connected battery.

Roy Lewallen, W7EL

Bruce W.1 wrote:

I wrote the program and will make it available to anyone that wants it.
I runs on Windows and the .NET Framework. Works fine. The only problem
I have is remembering to disconnect the battery from the resistor after
it hits one volt, Doh! Some of them were pulled down to 0.4 volts
(under load) but they recover to about a volt at rest.

Yet one question still lingers in my mind. Is a discharge voltage to,
say, 1.1 volts under load or at rest?

Roy Lewallen wrote:

The end discharge voltage (generally 1.0 volt per cell for NiCd and NiMH
cells) is measured under load. After disconnecting the load, the voltage
will typically rise substantially, but its value isn't of any significance.

It's usually not recommended to discharge below 1.0 volt, but it doesn't
seem to cause any harm, at least if it's not done really often. I think
a cell is more likely to grow dendrites and short if it's left in an
extreme discharged state for an extended period, so it's probably a good
idea to put at least some charge back in before too awfully long if
you've discharged it particularly deeply. What is harmful is reverse
charging of the cell. But that happens only when you have an external
source of current, like other cells in a series connected battery.

Roy Lewallen, W7EL

=======================================

Thanks for your help Roy. See you at the Dayton QRP Suite.

Bruce AF8F

Roy Lewallen wrote:

The end discharge voltage (generally 1.0 volt per cell for NiCd and NiMH
cells) is measured under load. After disconnecting the load, the voltage
will typically rise substantially, but its value isn't of any significance.

It's usually not recommended to discharge below 1.0 volt, but it doesn't
seem to cause any harm, at least if it's not done really often. I think
a cell is more likely to grow dendrites and short if it's left in an
extreme discharged state for an extended period, so it's probably a good
idea to put at least some charge back in before too awfully long if
you've discharged it particularly deeply. What is harmful is reverse
charging of the cell. But that happens only when you have an external
source of current, like other cells in a series connected battery.

Roy Lewallen, W7EL

=======================================

Thanks for your help Roy. See you at the Dayton QRP Suite.

Bruce AF8F