The industry standard for discharging a NiCad cell is .7 volt per cell.
Below that cell reversal will likely occur and destroy the pack. Been doing
it that way with many thousands of packs for over 40 years which makes me
too old to change my mind. We recycle over 1000 lbs of NiCad's every year
of which about half died way too soon. A good (Sanyo) cell will have at
lest 500 charge/discharge cycles if charged and discharged correctly but
many only last 200 cycles due to abuse.
Mark
Nashville
----- Original Message -----
From: <jibjib@att.net>
To: "Karl Vacek" <KVacek@Ameritech.net>; <shop-talk@autox.team.net>
Sent: Tuesday, July 14, 2009 10:18 PM
Subject: Re: [Shop-talk] Recharging a Ni-Cad Battery
Karl,
I did say very occassionally and I do not believe that NiCad packs will have
an issue with it, especially at the 1/10 C rate I also discussed.
I would not do this with NiMH and certainly not any Lithium chemistry. which
defnitely require balanced charging or regular balancing. I only use
balanced chargers on Lithium cells, but simple 1/10 C charging on everything
else.
Complete discharging of NiCad (and only NiCad) packs is not an uncommon
practice in the RC world.
Jack
-------------- Original message from "Karl Vacek"
<kvacek@ameritech.net>: --------------
>
> > Also, NiCads, unlike many other batteries, have no issue and may benefit
> > from a very occassional, full and complete discharge.
> >
> > Jack
>
>
> This is a little off from Eric's dive light question, but...
>
> As an R/C pilot you can't mean that. You have a potentially lethal weapon,
> and an investment of hundreds (or thousands) of dollars flying around
> completely dependent upon the health of your radio batteries.
>
> If you're referring to completely discharging a nicad back as opposed to
> one
> individual cell, DO NOT do it.
>
> Maybe one or two complete discharges won't do any noticeable harm, but
> more
> than a few will begin to destroy the weakest cell in the pack. As the
> cells
> discharge, one reaches 0 volts first, and the current from the others
> flowing through it as they continue to discharge will reverse-charge that
> weakest cell, reversing its polarity. Then the second-weakest cell will
> reach 0 volts and reverse polarity, and so forth, till only one cell is
> left
> with any voltage.
>
> Do that a few times and you've ruined one or more cells and thus ruined
> the
> pack. That's why there are smart chargers and dischargers and
> expanded-scale voltmeters to monitor the state of charge and discharge of
> nicad cells and battery packs and exercise them as well.
>
> Karl
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