Thread: NiCd vs. NiMh
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E Z Peaces E Z Peaces is offline
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Default NiCd vs. NiMh

ransley wrote:
On Jul 4, 9:09 pm, E Z Peaces wrote:
ransley wrote:
On Jul 4, 9:32 am, wrote:
As far as chargers go......Buy the cheapest, slowest dumb
charger/chargers you can and plug them into the cheapest
electrical timer you can find. Set the timer for a couple hours
a day and you'll always have a fresh set of batteries, you'll
never have to worry about overcharging, and you'll have
more money in your pocket for other toys.
The cheapest charger may only get Nimh near 90% charged if its a Nicad
profile
The cheapest slowest dumb chargers can easily overcharge a NIMH
battery. That is why they are dumb. By using the timer set for just a
couple hours a day you nullify any damage caused by overcharging.
For my RC cars and a dumb charger I used to measure voltage, when it
dropped the slightest amount they were charged, that is also when they
get warm, but temp is hard to monitor when batteries are in a charger
that produces heat itself. The best chargers would have to measure
voltage and compute when peaking occurs by voltage drop, the temp
method I dont trust. My sony cameras came with good inexpensive
chargers for NimH

Both my NiMH chargers monitor for the voltage change. I don't think
it's foolproof. Occasionally over the years when charging seemed to
take too long, my cells felt too hot. If I were charging manually, I
would scan the pack with an infrared thermometer. That should show when
the temperature of a cell rose.- Hide quoted text -

- Show quoted text -


Mine get warm but its the charger itself thats warm also, in RC packs
the pack is outside the charger so the chargers heat cant affect them.
You could attatch leads of a V meter, I place the thin probe in as im
placing the AA cell in my cheap sony charger, then you can monitor
when voltage peaks and starts to drop a few hundreths of a volt, as it
peaks the battery heats , thats when charging is 100%. The method is
accurate but how accurate is any charger, there are defects made all
the time.


When my charger stays on much longer than usual and the cells are hot, I
remove them, wait a minute, and reinsert them. Within a minute, the
charger will shut off. To me, that's evidence that the cells were
charged but the voltage drop was not detected.

I believe bubbles can form in nickel batteries during charging. I think
they can sometimes keep the charger from seeing a voltage drop at the
end of a charge. Touching to see if a cell is hot is how I detect a
problem. In the future, I'll look for a charger that monitors temperature.