[aprssig] NiCd Lessons relearned

Michael Barnes barnmichael at gmail.com
Fri Jul 14 17:16:47 CDT 2017


I have experienced so much grief from NiCd batteries over the years, I will
never use them again if I can help it. I got a real nice screw gun a couple
years ago for Christmas that has NiCd batteries. Every time I go to use it,
the batteries are dead and I have to wait a couple hours to charge one. I
have a small electric screwdriver with lithium batteries that was in
storage for almost a year. When I unpacked it, I used it heavily for a week
before I had to charge it. It held its charge all that time in storage.
When I can, I'm going to have my remaining NiCd packs converted to lithium
cells.

Michael WA7SKG


On Jul 14, 2017 16:14, "Robert Bruninga" <bruninga at usna.edu> wrote:

> Lesson relearned on NiCd charging:  Several years ago I made three 12v
> batteries from D cell NiCd’s.
>
>
>
> They have been a huge disappointment.  They are only used once or twice a
> year on critical field work and always fail far earlier than estimates.
> But I always just charge them the night before with a fixed voltage charge
> of 14 volts since I most often forget about batteries I put on charge and
> end up ruining most of them.  Charging at fixed voltage is safe…
>
>
>
> For the AT Golden Packet event tomorrow, last night I left them on my
> usual 14 volt overnight charge and they were “fully charged” by morning,
> only drawing a 50 mAh each in the morning at 14 volts..
>
>
>
> Put them on a battery analyzer and their capacities came in at 10%, 8% and
> 3%.  Then the battery analyzer quick charged them at 1C rate for 1 hour
> with them getting up to 16 or 18 volts, then a 4 hour equalization charge
> of 0.1C or 400 mA.
>
>
>
> Then it retested them and got 75%, 65% and 85% of rated capacity!
>
>
>
> So, Apparently little-used NiCd’s are not going to get a good charge from
> a FIXED voltage charge!
>
>
>
> Wish I had time to cycle them two more times.  On batteries at work we see
> huge recoveries from little used NiCd’s when “rejuvenated” which is the 3
> cycles of charge and discharge I started with above.
>
>
>
> Bob
>
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